Perinatal Neuroprotection in Preterm Birth

Abstract

Preterm birth is one of the main causes of perinatal morbidity and mortality. The rate of grade III and IV cerebral hemorrhages in infants with a birth weight of less than 1500 g in Germany in 2022 was 2.97% and the periventricular leukomalacia rate was 1.07%. In addition to these severe forms of brain damage which are visible on sonography, recent MRI studies carried out at the calculated due date of affected children also showed diffuse white and grey matter injuries, especially of the basal ganglia and the cerebellum, indicating impaired brain development and function. To offer these children the best possible start in life it is essential that they are cared for in a level I perinatal center right from the start. In addition, a number of perinatal measures are available which may significantly improve the neuronal development in preterm infants. They include the use of antenatal corticosteroids and magnesium as well as deferred cutting of the umbilical cord. Recent studies have shown that in contrast to term-born infants, hypothermia treatment is unsuitable for neuroprotection in premature babies. As secondary and tertiary cell damage may occur days or even weeks after the primary insult due to persistent inflammation and the lack of trophic stimulation, in addition to providing premature infants with the best possible initial care, it is also necessary to optimize subsequent care in the intensive care unit in terms of providing a neuronal-positive stimulating environment. Breastfeeding and supply of breast milk are particularly important in this context.

 

MissingLinkText

Keywords

preterm birth - periventricular-intraventricular hemorrhage - neuroprotection - periventricular leukomalacia

Introduction

Preterm birth is one of the most important causes of perinatal morbidity and mortality, with around half of all cases of perinatal mortality occurring in preterm babies weighing less than 1500 g [1]. Although the incidence of preterm birth in Germany has continually decreased from 8.87% in 2014 to 7.87% in 2023, the mortality of extremely preterm infants remains high [2]. Many of the children who survive are severely affected by brain damage, much of which occurs postnatally. In individual cases, however, there are indications that brain damage had an antenatal genesis. Brain damage usually has multifactorial origins. Causes include hypoxia/ischemia and ascending infection as well as cardiovascular changes resulting from invasive ventilation or other invasive interventions required due to the immaturity of the infant ([Fig. 1]) [3] [4] [5] [6] [7]. The rate of grade III and IV cerebral hemorrhages in babies with a birth weight of less than 1500 g in 2022 was 2.97% and the rate of periventricular leukomalacia was 1.07% [2].

Fig. 1 Perinatal brain damage in preterm infants is caused by a number of factors. They include hypoxia/ischemia, ascending infection as well as cardiovascular changes resulting from invasive ventilation or other invasive interventions required because of the immaturity of the infant. This leads to cell loss from astrogliosis, changes in oligodendrocyte development and consequently impaired myelination. Interventions to reduce brain damage in affected infants are possible in every phase, i.e., the primary, secondary, or tertiary phase, after the original insult [8]. Source: Molloy EJ, El-Dib M, Soul J et al. Neuroprotective therapies in the NICU in preterm infants: present and future (Neonatal Neurocritical Care Series). Pediatr Res 2024; 95: 1224–1236. DOI: 10.1038/s41390-023-02895-6. © The Author(s) 2023. Licensed under a Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/). Adapted.).

In addition to these severe, sonographically visible forms of brain damage, MRI of affected children carried out on the calculated due date also shows diffuse white and gray matter injuries, especially of the basal ganglia and the cerebellum which are indications for impaired brain development and function [9]. Morphologically this is caused by astrogliosis and insufficient maturation of oligodendrocytes, which leads to impaired myelination due to persistent inflammation and a lack of growth factors [10] [11] [12] [13] [14]. Experimental studies show that this inflammation and inadequate trophic stimulation result in further cell damage occurring in the days and weeks subsequent to the primary insult. This is known as the primary, secondary, and tertiary phase of the insult [8].

Although the prevalence of infantile cerebral palsy as a late sequelae of severe neuronal damage is currently 6.5–12% and has declined following improvements in clinical care in recent years, the rate of additional neurological disorders such as cognitive impairment, impaired vision, hearing impairment, behavioral disorders, and psychiatric disorders in extremely preterm infants is estimated to be 25–50% [15] [16] [17] [18].

A number of perinatal measures are now available which can significantly improve the neuronal outcomes of preterm infants. This review throws a light on currently available neuroprotective strategies which are primarily aimed at countering the primary insult. Neonatology interventions which can improve the neuronal outcome days and even weeks after birth are also discussed.

 

MissingLinkText

Search of the Literature

A selective search of the literature up until December 2024 was carried out in PubMed using the key terms “neuroprotection,” “intra-/periventricular hemorrhage,” “periventricular leucomalacia,” “preterm birth,” “preterm delivery.” The starting point was our last review on this issue [19]. Relevant prospectively randomized studies, meta-analyses and review articles were selected for this article. Cross-references to other important works were considered.

 

MissingLinkText

Neuroprotective Strategies in the Primary Phase

Morphology of the germinal matrix

The overwhelming majority of neonatal cerebral hemorrhages start in the germinal matrix [20]. If we want to understand the approach used for neuroprotective strategies against this form of injury, it is first necessary to engage with the specific morphology of this region of the brain.

In contrast to other brain areas such as the cerebral cortex or white brain matter, the germinal matrix is characterized by very strong angiogenesis. The extremely rapid endothelial proliferation results in a high vascular density. The pronounced vascularization of the germinal matrix is the result of the high energy needs of neuronal and glial precursor cells which migrate from here into the different brain regions where they mature further [21].

Rapid angiogenesis in the germinal matrix is accompanied by inadequate maturation of the blood vessels. Pericytes are an essential component of the walls of capillaries, venules, and arterioles ([Fig. 2]) [22]. They are embedded in the basement membrane and cover the endothelial cells. Pericytes play a decisive role in directing angiogenesis. They stabilize vascular structures, maintain the blood-brain barrier and control the neurovascular unit, i.e., the endothelium, astrocytes and neurons [23] [24] [25] [26]. If they are stimulated by angiogenetic factors such as platelet-derived growth factor-B (PDGF-B), angiopoietin, sphingosine-1-phosphate or transforming growth factor β (TGFβ), they degrade the basement membrane, induce the formation of new blood vessels, stabilize the structure of new blood vessels by synthesizing extracellular matrix components, and promote maturation of the corresponding endothelial cells [27] [28].

Fig. 2 Cross-sectional diagram of the blood-brain barrier: endothelium with tight junctions, basement membrane, pericytes, astrocyte end-feet [21]. GFAP = glial fibrillary acidic protein. Reprinted from Clinics in Perinatology, Volume 41, Issue 1, Praveen Ballabh, Pathogenesis and Prevention of Intraventricular Hemorrhage, 47–67, 2014, with permission from Elsevier. The Creative Commons license does not apply to this content. Any further use is subject to permission from Elsevier. [rerif]

Compared to other areas of the brain, the vascular walls in the germinal matrix have few pericytes [29]. This is probably a consequence of the low TGFβ concentrations in the uterus and in the initial days after birth. The low TGFβ level stimulates endothelial proliferation, leading to strong angiogenesis which is characterized by unstable vascular walls due to the lack of pericytes [21].

The basement membrane is another important component contributing to vascular stability ([Fig. 2]). It consists of laminin, collagen, fibronectin, and the heparan-sulfate proteoglycan perlecan [30] [31] [32]. Postmortem examinations of extremely preterm neonates have shown that fibronectin concentrations in the blood vessels of the germinal matrix are significantly lower than in other brain regions ([Fig. 2]) [33]. Similar to pericytes, synthesis of the basement membrane is stimulated by TGFβ. Low TGFβ levels are associated with an immature basement membrane and, consequently, with unstable vascular walls [21].

The endothelium, basement membrane and pericytes are encased by astrocyte end-feet ([Fig. 2]). Astrocyte end-feet are an essential component of the blood-brain barrier; they consist of intermediate filaments whose major component is glial fibrillary acidic protein (GFAP) [34]. Postmortem studies of preterm babies have shown that the GFAP content of astrocytes in the germinal matrix is lower than in other brain regions and end-feet coverage of the vascular walls is similarly lower ([Fig. 3]) [35]. This finding is another contributary cause to the instability of the vascular network in the germinal matrix [36] [37] [38].

Fig. 3 Compared to white matter vasculature, germinal matrix vessels are characterized by fibronectin deficiency and lower astrocyte end-feet coverage [21]. a Representative frozen section through the germinal matrix and white matter in a preterm infant aged 24 GW. Fibronectin, visualized here in red with immunofluorescence, is strongly expressed in the white matter vasculature but not in germinal matrix vessels (arrows). Scale: 20 µm. b Representative frozen section through the germinal matrix and white matter in a preterm infant aged 24 GW. The endothelium is visualized in red with immunofluorescence and glial fibrillary acidic protein (GFAP) in the astrocytes is green. GFAP-positive astrocyte end-feet are wrapped closely around the external endothelium in white matter vasculature but are barely present in the germinal matrix (arrows). Scale: 20 µm. Reprinted from Clinics in Perinatology, Volume 41, Issue 1, Praveen Ballabh, Pathogenesis and Prevention of Intraventricular Hemorrhage, 47–67, 2014, with permission from Elsevier. The Creative Commons license does not apply to this content. Any further use is subject to permission from Elsevier. [rerif]

Measurement of hypoxia-inducible factor-1α indicates that oxygen concentrations in the germinal matrix are lower than in the adjacent white brain matter. This is probably due to the high oxygen requirements of the neuronal and glial precursor cells found in white matter. A low oxygen concentration activates the release of vascular endothelial growth factor (VEGF) and angiopoietin and simultaneously inhibits TGFβ. This stimulates angiogenesis. Immature vessels are formed, which consist almost exclusively of endothelial cells with a low percentage of pericytes, decreased fibronectin in the basement membrane, and reduced GFAP concentrations in the astrocytes [21].

It is interesting in this context that intraventricular hemorrhages occur predominantly in the first three days of life and that the incidence of intraventricular hemorrhage decreases strongly thereafter [20]. This is very probably due to increasing oxygenation of the germinal matrix, which results in a decrease in VEGF and angiopoietin and an increase of TGFβ which inhibits angiogenesis [21].

 

MissingLinkText

Antenatal steroids (ANS)

It is well-known and confirmed in a recent meta-analysis that ANS administration reduces neonatal mortality (RR 0.78, 95% CI 0.70–0.87), respiratory distress syndrome (RDS) (RR 0.71, 95% CI 0.65–0.78) and the rate of intraventricular hemorrhage (RR 0.58, 95% CI 0.45–0.75) [39].

For many years it was assumed that glucocorticoids only improve neonatal outcomes by reducing the incidence of RDS. A stable respiratory situation reduces the need for numerous interventions in neonates such as suctioning and the placement and replacement of access lines, etc., which can trigger strong fluctuations in cerebral blood flow. As very immature preterm infants have limited cerebral autoregulation [40], this leads to strong pressure fluctuations in the very vulnerable vasculature of the germinal matrix. The consequence is intraventricular and periventricular hemorrhage [20] [41].

Experimental studies in animals and postmortem studies in human fetuses have shown that antenatal administration of betamethasone suppresses endothelial proliferation ([Fig. 4]). Betamethasone administration contributes to stabilizing the vasculature by enhancing pericyte coverage and elevating GFAP concentrations in astrocytes. These changes are driven by glucocorticoid-induced inhibition of VEGF and increased release of TGFβ [29] [33] [42].

Fig. 4 Glucocorticoids suppress endothelial proliferation [42]. a Pregnant rabbits were administered 0.2 mg/kg betamethasone on days 27 and 28 of gestation. Rabbit fetuses were delivered by caesarean section on day 29 of gestation (due date: 32nd day of gestation) and their brains were examined. The upper two images show representative frozen sections of the germinal matrix. The endothelium was visualized immunohistochemically with CD 31 antibodies (red), Ki67 (green) was used as the proliferation marker. Double staining (endothelial proliferation; arrows) was not observed after betamethasone administration. Scale 20 µm. b Representative cross-section through the germinal matrix and white brain matter of two infants aged 23 GW with and without the administration of betamethasone. The endothelium was visualized immunohistochemically with CD 34 antibodies (red); Ki67 (green) was used as the proliferation marker. Double staining (endothelial proliferation; arrows) was seen much less after betamethasone administration. Scale: 50 µm. Source: Govindaiah Vinukonda, Krishna Dummula, Sabrina Malik, Furong Hu, Carl I. Thompson, Anna Csiszar, Zoltan Ungvari, and Praveen Ballabh, Effect of Prenatal Glucocorticoids on Cerebral Vasculature of the Developing Brain, Stroke, 2010, Volume 41, Number 8, 1766–1773, DOI: 10.1161/strokeaha.110.588400, The American Heart Association, with permission from Wolters Kluwer Health Inc. The Creative Commons license does not apply to this content. Use of this material in any format is prohibited without written permission from the publisher, Wolters Kluwer Health, Inc. Please contact [e-mail] for further information. [rerif]

Unfortunately, there are no experiments showing how long the effects of betamethasone on the vascular morphology persist. However, a recent observational study by Clyman et al. has investigated whether the rate of intraventricular and periventricular hemorrhage in extremely preterm infants < 28 GW (N = 410) rises again if the infants are born more than 10 days after the antenatal administration of betamethasone [43]. The study also investigated whether a second administration of ANS 10 days after the first administration could prevent a possible increase in cerebral hemorrhages. Multivariable regression showed that the severe cerebral hemorrhage rate in infants born 10 days after ANS administration was significantly higher compared to infants born between one and nine days after ANS administration (OR [95% CI]: 2.9 [1.1–7.2]). Of the 120 infants born 10 days or more after the first administration of ANS, 64 (53%) received a second cycle of betamethasone. The rate of severe cerebral hemorrhages in these children was not higher than that of the group of infants born between one and nine days after the first ANS administration and was significantly lower than that of infants born 10 days or more after the first ANS administration who did not receive a second dose (OR [95% CI]: 0.1 [0.02–0.65]) [43]. This would indicate that the effect of glucocorticoids on vascular stability in the germinal matrix is merely transient.

The benefits of ANS administration on the rate of cerebral hemorrhage are especially obvious in fetuses aged ≤ 30 GW; the effect disappears in older fetuses [44]. This is due to the increasing regression of the germinal matrix with advancing gestational age. From week 36 of gestation, the germinal matrix is barely detectable [21].

In other words: based on the currently available data, omitting to administer ANS after 30 weeks of gestation is not associated with an increased risk of cerebral hemorrhage. However, the possibility cannot be excluded that ANS administration may have a neuroprotective effect on smaller, sonographically invisible lesions in fetuses aged more than 30 GW. On the other hand, adverse effects on the further development of children have been reported for ANS administration and delivery after 37 weeks of gestation [45] [46]. The administration or omission of ANS therefore remains a difficult decision and the risks and benefits must be weighed up.

 

MissingLinkText

Magnesium

Antenatal intravenous high-dose administration of magnesium sulfate already demonstrated a neuroprotective effect in premature babies with a birth weight of < 1500 g in observational studies carried out in the 1990s [47]. Those observations have since been verified in numerous prospective randomized studies. The most recent meta-analysis published in 2024 included six studies with 5917 patients and 6759 babies born < 34 GW in its randomization [48]. All the studies were carried out in high-income countries (2 in the USA, 2 across Australia and New Zealand, 1 each in Denmark and France) between 1995 and 2018. The primary study outcomes “cerebral palsy” (RR 0.71, 95% CI 0.57–0.89) and “death or cerebral palsy” (RR 0.87, 95% CI 0.77–0.98) at two years of corrected age were reduced significantly by the antenatal administration of magnesium sulfate. Magnesium did not have a significant effect on mortality at the age of two years nor on further development at school age ([Table 1]) [48].

Table 1 Perinatal neuroprotection for preterm infants born < 34 + 0 GW after antenatal magnesium.

	RR (95% CI)	Number of children (Number of RCT)	Level of evidence (GRADE)
Meta-analysis of the neuroprotective effect of antenatal magnesium in premature children born < 34 + 0 GW [48]. 95% CI = 95% confidence interval; GRADE = Grading of Recommendations Assessment, Development and Evaluation; RCT = randomized controlled trial; RR = relative risk
Cerebral palsy at the age of 2 years	0.71 (0.57–0.89)	6107 (N = 6)	High
Mortality or cerebral palsy at the age of 2 years	0.87 (0.77–0.98)	6481 (N = 6)	High
Mortality at the age of 2 years	0.96 (0.82–1.13)	6759 (N = 6)	Moderate
Severe neuronal development disorders at school age	0.92 (0.53–1.62)	940 (N = 2)	Very low

Numerous mechanisms which can mediate the neuroprotective effect of magnesium have been investigated in experiments. Large amounts of excitatory amino acids such as glutamate, succinate, etc. are released presynaptically during acute cerebral ischemia. These neurotransmitters activate neuronal N-methyl-D-aspartate (NMDA) receptors which regulate calcium channels. As a result, large amounts of calcium ions flow down an extreme extra-intracellular concentration gradient into the cell. An excessive increase of intracellular calcium levels leads to cell damage through the activation of proteases, lipases, and endonucleases [49]. Magnesium ions regulate the voltage-dependent NMDA channels and protect the brain from lesions mediated by the NMDA receptors [50] [51]. Magnesium additionally suppresses cerebral seizures and is an effective vasodilator [52] [53]. Both effects are neuroprotective. Magnesium also decreases the release of nitrogen oxide and thereby reduces the post-ischemic production of oxygen radicals [54].

Experimental studies have shown that antenatal administration of magnesium induces protective preconditioning in the immature brain [55]. When magnesium was administered between twelve hours and six days before a hypoxic-ischemic insult, subsequent brain damage was markedly lower. Magnesium modulates the synthesis of mRNAs/miRNAs which are involved in mitochondrial functioning and metabolism. Analysis of the metabolome (H+-NMR) showed that magnesium attenuates the hypoxic-ischemic induced increase in succinate in the brain and reduces depletion of high-energy phosphates. Succinate is an excitatory neurotransmitter which causes neuronal cell damage if it is present in high concentrations. The administration of magnesium also preserves mitochondrial respiration, reduces oxygen free radical formation, and remediates inflammatory processes after a hypoxic-ischemic insult [55].

 

MissingLinkText

Management of cord clamping

The transition of the fetal circulation from the intrauterine to the postnatal status is an extremely vulnerable phase for the immature brain. As mentioned above, extremely preterm neonates have very limited cerebral autoregulation [40]. Strong fluctuations in systemic blood pressure therefore pass unhindered into the cerebral vascular bed, where they cause intraventricular and periventricular hemorrhages, especially in the germinal matrix [20] [41].

It is therefore important to ensure that immediate care of extremely preterm neonates avoids interventions which could provoke such fluctuations in systemic blood pressure. This specifically includes cord milking carried out with the notional idea of providing the neonate an “extra volume of blood.”

In 2019, Katheria et al. published a study in which milking of the umbilical cord four times was compared with deferred cord clamping in 540 infants with gestational ages ranging from 23 to 31 GW [56]. The primary study outcome “death or severe cerebral hemorrhage” did not differ significantly between groups (cord milking: 29/236 [12%] vs. deferred cord clamping: 20/238 [8%]; risk difference 4% [95% CI] −2%–9%; P = 0.16). But the rate of severe cerebral hemorrhage in the subgroup of neonates born at 23–27 GW after umbilical cord milking was almost four times higher compared to the group with deferred cord clamping (cord milking: 20/93 [22%] vs. deferred cord clamping: 5/89 [6%]; risk difference 16% [95% CI] 6%–26%; P = 0.002). These differences were no longer observed in older neonates (28+0–31+6 GW) ([Table 2]), although the statistical power was insufficient to definitively resolve this issue [56].

Table 2 Rate of severe cerebral hemorrhage in preterm infants born from 23 + 0 to 31 + 6 GW after milking of the umbilical cord compared with infants treated with deferred cord clamping. Data from: [56].

Gestational age (GW)	Cord milking	Deferred cord clamping	Risk difference (%)	P value	P value for interaction
	Severe cerebral hemorrhage grade III–IV (N)
23+0–31+6	20/236 (8%)	8/238 (3%)	5 (1–9)	0.02
23+0–27+6	20/93 (22%)	5/89 (6%)	16 (6–26)	0.002	0,003
28+0–31+6	0/143 (0%)	3/149 (2%)	−2 (−4–1)	0.24

The medical professionals responded quickly to these data. So-called “birth trolleys” were developed which permit deferred cord clamping at the time of delivery even for extremely preterm neonates and still allow immediate neonatal care to be provided. Deferred cord clamping should always be preferred for preterm infants as it permits physiological transition of the cardiovascular system from the intrauterine to the postnatal phase [57] [58]. A “vent first” strategy is key, i.e., the cord should not be clamped before the lungs have inflated [59].

 

MissingLinkText

Hypothermia

The use of mild hypothermia (33°C core body temperature) over a period of 72 hours to treat asphyctic term-born infants is now clinical standard. Six randomized studies on this topic were published between 2005 und 2011. The results of these studies were summarized in a meta-analysis published in 2013 [60]. A total of 1344 children were included. The primary outcome “death or major neurodevelopment disability at the age of 18–22 months” was reduced by 25% (RR 0.75, 95% CI 0.68–0.83). The number needed to treat was seven [60].

What was not clear was whether preterm infants would also benefit from this intervention. It was not possible to rule out that the typical complications of premature neonates such as cerebral hemorrhage, necrotizing enterocolitis, or coagulation disorders might be exacerbated by mild hypothermia. For this reason, the Eunice Kennedy Shriver NICHD initiated a prospective randomized study which included 168 preterm infants born in 19 perinatal centers in the USA between 2015 and 2022. Infants showing signs of neonatal encephalopathy were recruited into the study. Encephalopathy was clinically diagnosed using the Thompson score and was a risk factor for the development of hypoxic-ischemic brain damage. Infants with a birth weight of < 1500 g, malformations, or a body temperature of < 34°C were excluded. Core body temperature was lowered to 33.5°C for 72 h in the intervention group [61].

The primary study outcome “death or moderate/severe neurodevelopment disability at the age of 18–22 months” affected 29 out of 83 infants (35%) in the intervention group and 20 of 69 infants (29%) in the control arm (RR 1.11, 95% CI 0.74–2.00). The probability of harm by hypothermia was 74% ([Table 3]). When stratified by gestational age, the incidence of the primary study outcome was higher in the hypothermia group for every week of gestation [61].

Table 3 Use of mild hypothermia in preterm infants born 33+0–35+6 GW with neonatal encephalopathy.

	Hypothermia		Normothermia
	n/N	%	n/N	%	RR (95% CI)	Probability of harm
Preterm infants born between 33 + 0 and 35 + 6 GW with neonatal encephalopathy were recruited. Core body temperature was lowered to 33.5 °C for 72 h in the intervention group. 95% CI = 95% confidence interval; RR = relative risk. Data from: [61]
Death or moderate or severe disability	29/83	35	20/69	29	1.11 (0.74–2.00)	74%
Death	18/83	22	9/69	13	1.38 (0.79–2.85)	87%
Survival with moderate or severe disability	11/83	13	11/69	16	0.86 (0.46–1.63)	32%

Mortality alone was 22% in the intervention group and 13% in the control group (RR 1.38, 95% CI 0.79–2.85). The probability of harm by hypothermia was 87% ([Table 3]). No differences in known side effects of hypothermia (cardiac arrhythmia, persistent metabolic acidosis, severe bleeding, skin lesions) were observed. Hyperglycemia was observed more often but the difference was not significant (23 vs. 12%) (RR 1.64, 95% CI 0.92–3.27) [61].

Mild hypothermia does not reduce mortality or the rate of moderate/severe neurodevelopmental disability at the age of 18–22 months in preterm infants. On the contrary, this intervention in preterm infants causes additional harm [61]. It is possible that hypothermia-induced hyperglycemia plays a role in this. Studies show that elevated glucose levels may exacerbate hypoxic-ischemic brain damage [62].

 

MissingLinkText

 

MissingLinkText

Neuroprotective Strategies in the Secondary and Tertiary Phase

As secondary and tertiary cell damage can occur days or even weeks after the primary insult due to persistent inflammation and lack of trophic stimulation ([Fig. 1]) [12] [63], in addition to providing preterm infants with the best possible initial care, it is necessary to optimize the subsequent care provided in the intensive care unit.

Clinical measures

The aim of primary care provided to very preterm neonates is to avoid high fluctuations in CO₂, blood pressure, and temperature [64] [65] [66]. If possible, invasive ventilation should not be used initially. The less invasive surfactant administration (LISA) method has proven to be very useful [67]. It is also important to prevent acidosis [68]. The head should be placed in a neutral midline position [69] and painful interventions should be minimized [70]. Balanced electrolyte levels are important, especially serum sodium concentrations [71].

As the most recent studies have shown, implementing appropriate standard operating procedures which include the above-listed measures reduces perinatal brain damage rates and improves the long-term neurological development of these children [72] [73] [74] [75] [76]. In addition to acute care, further measures may promote neuroplasticity and psychomotor maturation of the infants and thereby counter secondary and tertiary cell damage [8]. Such measures include early skin-to-skin contact (kangaroo care) [77] [78], avoiding strong light and loud acoustic stimuli [79], positive stimulating sounds [80], reinforcing good physiological neonatal sleep-wake cycles [81], family-centered care [82], parental voices with parents talking to their children [81] [83], and positive reinforcement of social interactions [84]. Breastfeeding and breast milk intake play an especially important role.

 

MissingLinkText

Breastfeeding and breast milk intake

Breast milk provides neonates with the appropriate physiological nutrition and is therefore recommended for all neonates. It is associated with numerous positive effects on the child’s short-term and long-term health (protection against infections, decreased incidence of metabolic syndrome disorders) and with better neurocognitive development.

For mothers of preterm born infants, initiating and maintaining lactation during the transition to breastfeeding presents specific challenges which can mean that preterm infants have a high risk of not being fed with their own mother’s milk and subsequently not being breastfed.

Numerous retrospective comparative studies have confirmed that being fed with breast milk obtained from the infant’s own mother and breastfeeding are associated with better neurological outcomes in preterm infants [85] [86] [87] [88] [89]. A joint analysis of two population-based French studies [89] showed that despite suboptimal initial weight gain, breastfed children showed better cognitive development at the age of five years.

The underlying mechanisms have been discussed a lot. It has often been pointed out that there is an association between breastfeeding and socioeconomic status, which in turn may determine the neurological outcome. However, the observed effect of breastfeeding remains, even after adjustment for socioeconomic factors.

Although breastfeeding is associated with greater focus by the mother on the infant which could be a partial explanation for the positive developmental effect, a number of different substances have been identified in human breast milk in recent years which could have an impact on brain development, for example, lactoferrin, various growth factors, cytokines [90], extracellular vesicles [91] [92], and even live cells, including stem cells [93]. In fact, in addition to the effects of breast milk intake and breastfeeding on functional parameters such as IQ and motor skills, morphological differences in brain architecture between breast milk-fed infants and formula-fed infants have been identified [94] [95] [96], which are ascribed to the impact of these components.

Feeding infants with breast milk also supports development of a healthy microbiome, which contributes to optimal development.

Interestingly, donor breast milk is not superior to formula if it is used to supplement breast milk from the infant’s own mother [97]. This is due, on the one hand, to changes in the composition of maternal breast milk, which changes and adapts to the infant’s gestational age and the child’s respective needs over the course of lactation [98] and, on the other hand, due to the fact that donor milk is subjected to various types of treatment such as refrigeration, freezing or pasteurization, which change the biological properties of the milk [99].

The way in which breast milk is administered also has a non-negligible impact on its biological effects. During breastfeeding, the physiological form of ingesting nutrition, the mucosa of the entire mouth, nose and throat comes into contact with breast milk. This has immunological impacts. Some substances may reach the brain transnasally. It is therefore recommended to combine tube feeding of breast milk in very and extremely preterm infants with the administration of small oral amounts [100]. Initial observations have also indicated that the nasal administration of maternal breast milk could have a therapeutic effect after perinatal brain damage [101] [102] [103] [104].

Promoting breastfeeding in the secondary and tertiary phase is therefore a very important neuroprotective measure.

 

MissingLinkText

Experimental approaches

Some inflammation-inhibiting interventions to minimize secondary and tertiary cell damage have already been investigated in animal experiments. For example, intracerebroventricular injection of the TNF inhibitor etanercept on days 3, 8 and 13 after umbilical occlusion significantly reduced induced brain damage in the white matter of immature ovine fetuses. It was also associated with improved maturation of oligodendrocytes and increased myelination [105].

Erythropoietin, an endogenous growth factor with anti-inflammatory, anti-excitotoxic and anti-apoptotic properties, has also been shown to have neuroprotective effects. Unfortunately, the findings of the five clinical studies carried out to date are inconsistent [106] [107] [108] [109] [110]. The two biggest studies did not find that erythropoietin administered to very preterm infants (24–32 GW) had any effect on neurological development at the age of two years [108] [110].

Melatonin is another potential candidate for neuroprotection. This naturally occurring indolamine is released from the epiphysis and regulates the circadian rhythm [111]. Melatonin crosses the placenta and the blood-brain barrier and is a known antioxidant [111]. A neuroprotective effect on hypoxic-ischemic and inflammatory brain damage has been observed in experimental studies [112]. In a prospective randomized study in preterm infants, lower lipid peroxidation was noted after the administration of melatonin in the first 21 days of life [113]. Further investigations into dosages and the timing of administration are planned in preclinical studies [114].

Caffeine, which is used clinically as a respiratory stimulant for preterm infants, is also being discussed as a potential neuroprotective agent [115]. Caffeine is an adenosine receptor antagonist with anti-inflammatory properties. In a cerebral ischemia/hypoxia model in neonatal rodents, caffeine was found to reduce induced brain damage and improved myelination and maturation of oligodendrocytes [116] [117] [118] [119]. In a prospective randomized study, infants with a birth weight < 1250 g who received caffeine for apnea had lower rates of cerebral palsy at the age of 18–21 months (4.4% vs. 7.3%; aOR 0.58, 95% CI 0.39–0.87) and neurological developmental delay (33.8 vs. 38.3%; aOR 0.81, 95% CI 0.66–0.99) [120].

Secondary and tertiary cell damage has been observed to occur days or even weeks after a cerebral perinatal insult due to insufficient trophic stimulation [12] [63]. In recent years interest has focused on the potential uses of pluripotent stem cells. These stem cells activate angiogenesis, neurogenesis, synaptogenesis, and neuronal networking. A meta-analysis of experimental studies in neonatal rodents showed that the use of neuronal stem cells can reduce the extent of infarction and significantly improve motor and cognitive functioning [121]. Unfortunately, there are currently only a few clinical phase I/II studies on this topic. Moreover, these studies mainly focus on chronic diseases rather than perinatal insults [122]. A study of preterm infants < 28 GW to investigate safety and viability after administering autologous mononuclear stem cells obtained from umbilical cord blood has been initiated [123].

 

MissingLinkText

 

MissingLinkText

Conclusion

Cerebral morbidity rates continue to be high in very preterm infants and significantly define the long-term morbidity of these infants. To offer these children an optimal start in life, it is very important that they are cared for in a level I perinatal center right from the start. There are also a number of perinatal measures which can significantly improve the neuronal development of preterm infants. They include the use of antenatal steroids, magnesium sulfate, and deferred cord clamping. As secondary and tertiary cell damage can occur days or even weeks after the primary insult due to persistent inflammation and lack of trophic stimulation, in addition to providing preterm infants with the best possible initial care, it is also necessary to optimize subsequent care in the intensive care unit in terms of providing a neuronal-positive stimulating environment. This includes early skin-to-skin contact (kangaroo care), avoiding strong light and loud acoustic stimuli, positive stimulating sounds, strengthening neonatal physiological sleep-wake cycles, providing family-centered care, parents talking to their infant, and positive strengthening of social interactions. Breastfeeding and feeding with breast milk are particularly important in this context.

 

MissingLinkText

 

MissingLinkText

Conflict of Interest

The authors declare that they have no conflict of interest.

• References/Literatur

• 1 Murray CJ, Vos T, Lozano R. et al. Disability-adjusted life years (DALYs) for 291 diseases and injuries in 21 regions, 1990–2010: a systematic analysis for the Global Burden of Disease Study 2010. Lancet 2012; 380: 2197-2223
• 2 IQTIG. Bundesauswertung 2023. Accessed September 23, 2024 at: https://iqtig.org/veroeffentlichungen/bundesqualitaetsbericht/
• 3 Yates N, Gunn AJ, Bennet L. et al. Preventing Brain Injury in the Preterm Infant-Current Controversies and Potential Therapies. Int J Mol Sci 2021; 22: 1671
• 4 Ophelders D, Gussenhoven R, Klein L. et al. Preterm Brain Injury, Antenatal Triggers, and Therapeutics: Timing Is Key. Cells 2020; 9: 1871
• 5 Hagberg H, Mallard C, Ferriero DM. et al. The role of inflammation in perinatal brain injury. Nat Rev Neurol 2015; 11: 192-208
• 6 Galinsky R, Lear CA, Dean JM. et al. Complex interactions between hypoxia-ischemia and inflammation in preterm brain injury. Dev Med Child Neurol 2018; 60: 126-133
• 7 Dean JM, Bennet L, Back SA. et al. What brakes the preterm brain? An arresting story. Pediatr Res 2014; 75: 227-233
• 8 Molloy EJ, El-Dib M, Soul J. et al. Neuroprotective therapies in the NICU in preterm infants: present and future (Neonatal Neurocritical Care Series). Pediatr Res 2024; 95: 1224-1236
• 9 Kidokoro H, Anderson PJ, Doyle LW. et al. Brain injury and altered brain growth in preterm infants: predictors and prognosis. Pediatrics 2014; 134: 444
• 10 Back SA. White matter injury in the preterm infant: pathology and mechanisms. Acta Neuropathol 2017; 134: 331-349
• 11 Verney C, Pogledic I, Biran V. et al. Microglial reaction in axonal crossroads is a hallmark of noncystic periventricular white matter injury in very preterm infants. J Neuropathol Exp Neurol 2012; 71: 251-264
• 12 Fleiss B, Gressens P. Tertiary mechanisms of brain damage: a new hope for treatment of cerebral palsy?. Lancet Neurol 2012; 11: 556-566
• 13 Chakkarapani AA, Aly H, Benders M. et al. Therapies for neonatal encephalopathy: Targeting the latent, secondary and tertiary phases of evolving brain injury. Semin Fetal Neonatal Med 2021; 26: 101256
• 14 Fleiss B, Murray DM, Bjorkman ST. et al. Editorial: Pathomechanisms and Treatments to Protect the Preterm, Fetal Growth Restricted and Neonatal Encephalopathic Brain. Front Neurol 2021; 12: 755617
• 15 Hüning B, Storbeck T, Bruns N. et al. Relationship between brain function (aEEG) and brain structure (MRI) and their predictive value for neurodevelopmental outcome of preterm infants. Eur J Pediatr 2018; 177: 1181-1189
• 16 Pascal A, Govaert P, Oostra A. et al. Neurodevelopmental outcome in very preterm and very-low-birthweight infants born over the past decade: a meta-analytic review. Dev Med Child Neurol 2018; 60: 342-355
• 17 Costeloe KL, Hennessy EM, Haider S. et al. Short term outcomes after extreme preterm birth in England: comparison of two birth cohorts in 1995 and 2006 (the EPICure studies). BMJ 2012; 345: e7976
• 18 Sellier E, Platt MJ, Andersen GL. et al. Decreasing prevalence in cerebral palsy: a multi-site European population-based study, 1980 to 2003. Dev Med Child Neurol 2016; 58: 85-92
• 19 Berger R, Söder S. Neuroprotection in preterm infants. Biomed Res Int 2015; 2015: 257139
• 20 Volpe J. Neurology of the Newborn. Philadelphia: Saunders; 1995
• 21 Ballabh P. Pathogenesis and prevention of intraventricular hemorrhage. Clin Perinatol 2014; 41: 47-67
• 22 Sá-Pereira I, Brites D, Brito MA. Neurovascular unit: a focus on pericytes. Mol Neurobiol 2012; 45: 327-347
• 23 Balabanov R, Dore-Duffy P. Role of the CNS microvascular pericyte in the blood-brain barrier. J Neurosci Res 1998; 53: 637-644
• 24 Jain RK. Molecular regulation of vessel maturation. Nat Med 2003; 9: 685-693
• 25 Armulik A, Genové G, Mäe M. et al. Pericytes regulate the blood-brain barrier. Nature 2010; 468: 557-561
• 26 Hirschi KK, D’Amore PA. Control of angiogenesis by the pericyte: molecular mechanisms and significance. EXS 1997; 79: 419-428
• 27 Gaengel K, Genové G, Armulik A. et al. Endothelial-mural cell signaling in vascular development and angiogenesis. Arterioscler Thromb Vasc Biol 2009; 29: 630-638
• 28 Lindahl P, Johansson BR, Levéen P. et al. Pericyte loss and microaneurysm formation in PDGF-B-deficient mice. Science 1997; 277: 242-245
• 29 Braun A, Xu H, Hu F. et al. Paucity of pericytes in germinal matrix vasculature of premature infants. J Neurosci 2007; 27: 12012-12024
• 30 Persidsky Y, Ramirez SH, Haorah J. et al. Blood-brain barrier: structural components and function under physiologic and pathologic conditions. J Neuroimmune Pharmacol 2006; 1: 223-236
• 31 Tilling T, Engelbertz C, Decker S. et al. Expression and adhesive properties of basement membrane proteins in cerebral capillary endothelial cell cultures. Cell Tissue Res 2002; 310: 19-29
• 32 Hallmann R, Horn N, Selg M. et al. Expression and function of laminins in the embryonic and mature vasculature. Physiol Rev 2005; 85: 979-1000
• 33 Xu H, Hu F, Sado Y. et al. Maturational changes in laminin, fibronectin, collagen IV, and perlecan in germinal matrix, cortex, and white matter and effect of betamethasone. J Neurosci Res 2008; 86: 1482-1500
• 34 Hawkins BT, Davis TP. The blood-brain barrier/neurovascular unit in health and disease. Pharmacol Rev 2005; 57: 173-185
• 35 El-Khoury N, Braun A, Hu F. et al. Astrocyte end-feet in germinal matrix, cerebral cortex, and white matter in developing infants. Pediatr Res 2006; 59: 673-679
• 36 Liedtke W, Edelmann W, Bieri PL. et al. GFAP is necessary for the integrity of CNS white matter architecture and long-term maintenance of myelination. Neuron 1996; 17: 607-615
• 37 Trimmer PA, Reier PJ, Oh TH. et al. An ultrastructural and immunocytochemical study of astrocytic differentiation in vitro: changes in the composition and distribution of the cellular cytoskeleton. J Neuroimmunol 1982; 2: 235-260
• 38 Ribotta MG, Menet V, Privat A. Glial scar and axonal regeneration in the CNS: lessons from GFAP and vimentin transgenic mice. Acta Neurochir Suppl 2004; 89: 87-92
• 39 McGoldrick E, Stewart F, Parker R. et al. Antenatal corticosteroids for accelerating fetal lung maturation for women at risk of preterm birth. Cochrane Database Syst Rev 2020; (12) CD004454
• 40 Milligan DW. Failure of autoregulation and intraventricular haemorrhage in preterm infants. Lancet 1980; 1: 896-898
• 41 Alderliesten T, Lemmers PM, Smarius JJ. et al. Cerebral oxygenation, extraction, and autoregulation in very preterm infants who develop peri-intraventricular hemorrhage. J Pediatr 2013; 162: 698-704.e2
• 42 Vinukonda G, Dummula K, Malik S. et al. Effect of prenatal glucocorticoids on cerebral vasculature of the developing brain. Stroke 2010; 41: 1766-1773
• 43 Clyman RI, Rosenstein MG, Liebowitz MC. et al. Betamethasone treatment-to-delivery interval, retreatment, and severe intraventricular hemorrhage in infants < 28 weeks’ gestation. Am J Obstet Gynecol 2025; 232: 400.e1-400.e10
• 44 Travers CP, Clark RH, Spitzer AR. et al. Exposure to any antenatal corticosteroids and outcomes in preterm infants by gestational age: prospective cohort study. BMJ 2017; 356: j1039
• 45 Räikkönen K, Gissler M, Kajantie E. Associations Between Maternal Antenatal Corticosteroid Treatment and Mental and Behavioral Disorders in Children. JAMA 2020; 323: 1924-1933
• 46 Räikkönen K, Gissler M, Tapiainen T. et al. Associations Between Maternal Antenatal Corticosteroid Treatment and Psychological Developmental and Neurosensory Disorders in Children. JAMA Netw Open 2022; 5: e2228518
• 47 Grether JK, Nelson KB, Emery 3rd ES. et al. Prenatal and perinatal factors and cerebral palsy in very low birth weight infants. J Pediatr 1996; 128: 407-414
• 48 Shepherd ES, Goldsmith S, Doyle LW. et al. Magnesium Sulfate Before Preterm Birth for Neuroprotection: An Updated Cochrane Systematic Review. Obstet Gynecol 2024; 144: 161-170
• 49 Berger R, Garnier Y. Pathophysiology of perinatal brain damage. Brain Res Rev 1999; 30: 107-134
• 50 Nowak L, Bregestovski P, Ascher P. et al. Magnesium gates glutamate-activated channels in mouse central neurones. Nature 1984; 307: 462-465
• 51 Hallak M, Hotra JW, Kupsky WJ. Magnesium sulfate protection of fetal rat brain from severe maternal hypoxia. Obstet Gynecol 2000; 96: 124-128
• 52 Euser AG, Cipolla MJ. Magnesium sulfate for the treatment of eclampsia: a brief review. Stroke 2009; 40: 1169-1175
• 53 Faragó M, Szabó C, Dóra E. et al. Contractile and endothelium-dependent dilatory responses of cerebral arteries at various extracellular magnesium concentrations. J Cereb Blood Flow Metab 1991; 11: 161-164
• 54 Garnier Y, Middelanis J, Jensen A. et al. Neuroprotective effects of magnesium on metabolic disturbances in fetal hippocampal slices after oxygen-glucose deprivation: mediation by nitric oxide system. J Soc Gynecol Investig 2002; 9: 86-92
• 55 Koning G, Leverin AL, Nair S. et al. Magnesium induces preconditioning of the neonatal brain via profound mitochondrial protection. J Cereb Blood Flow Metab 2019; 39: 1038-1055
• 56 Katheria A, Reister F, Essers J. et al. Association of Umbilical Cord Milking vs Delayed Umbilical Cord Clamping With Death or Severe Intraventricular Hemorrhage Among Preterm Infants. JAMA 2019; 322: 1877-1886
• 57 Seidler AL, Aberoumand M, Hunter KE. iCOMP Collaborators. et al. Deferred cord clamping, cord milking, and immediate cord clamping at preterm birth: a systematic review and individual participant data meta-analysis. Lancet 2023; 402: 2209-2222
• 58 Seidler AL, Libesman S, Hunter KE. iCOMP Collaborators. et al. Short, medium, and long deferral of umbilical cord clamping compared with umbilical cord milking and immediate clamping at preterm birth: a systematic review and network meta-analysis with individual participant data. Lancet 2023; 402: 2223-2234
• 59 Ott F, Kribs A, Stelzl P. et al. Resuscitation of Term Compromised and Asphyctic Newborns: Better with Intact Umbilical Cord?. Geburtshilfe Frauenheilkd 2022; 82: 706-718
• 60 Jacobs SE, Berg M, Hunt R. et al. Cooling for newborns with hypoxic ischaemic encephalopathy. Cochrane Database Syst Rev 2013; (01) CD003311
• 61 Laptook AR, Shankaran S, Faix RG. Hypothermia for Hypoxic-ischemic Encephalopathy: Second-generation Trials to Address Gaps in Knowledge. Clin Perinatol 2024; 51: 587-603
• 62 Lear CA, Koome ME, Davidson JO. et al. The effects of dexamethasone on post-asphyxial cerebral oxygenation in the preterm fetal sheep. J Physiol 2014; 592: 5493-5505
• 63 Lear BA, Lear CA, Davidson JO. et al. Tertiary cystic white matter injury as a potential phenomenon after hypoxia-ischaemia in preterm f sheep. Brain Commun 2021; 3: fcab024
• 64 Fabres J, Carlo WA, Phillips V. et al. Both extremes of arterial carbon dioxide pressure and the magnitude of fluctuations in arterial carbon dioxide pressure are associated with severe intraventricular hemorrhage in preterm infants. Pediatrics 2007; 119: 299-305
• 65 Miller SS, Lee HC, Gould JB. Hypothermia in very low birth weight infants: distribution, risk factors and outcomes. J Perinatol 2011; 31 (Suppl. 1) S49-S56
• 66 Vesoulis ZA, Flower AA, Zanelli S. et al. Blood pressure extremes and severe IVH in preterm infants. Pediatr Res 2020; 87: 69-73
• 67 Kuitunen I, Räsänen K. Less Invasive Surfactant Administration Compared to Intubation, Surfactant, Rapid Extubation Method in Preterm Neonates: An Umbrella Review. Neonatology 2024; 121: 485-493
• 68 Goswami IR, Abou Mehrem A, Scott J. et al. Metabolic acidosis rather than hypo/hypercapnia in the first 72 hours of life associated with intraventricular hemorrhage in preterm neonates. J Matern Fetal Neonatal Med 2021; 34: 3874-3882
• 69 Malusky S, Donze A. Neutral head positioning in premature infants for intraventricular hemorrhage prevention: an evidence-based review. Neonatal Netw 2011; 30: 381-396
• 70 Anand KJ. Clinical importance of pain and stress in preterm neonates. Biol Neonate 1998; 73: 1-9
• 71 Lee HJ, Lee BS, Do HJ. et al. Early sodium and fluid intake and severe intraventricular hemorrhage in extremely low birth weight infants. J Korean Med Sci 2015; 30: 283-289
• 72 Murthy P, Zein H, Thomas S. et al. Neuroprotection Care Bundle Implementation to Decrease Acute Brain Injury in Preterm Infants. Pediatr Neurol 2020; 110: 42-48
• 73 de Bijl-Marcus K, Brouwer AJ, De Vries LS. et al. Neonatal care bundles are associated with a reduction in the incidence of intraventricular haemorrhage in preterm infants: a multicentre cohort study. Arch Dis Child Fetal Neonatal Ed 2020; 105: 419-424
• 74 McLendon D, Check J, Carteaux P. et al. Implementation of potentially better practices for the prevention of brain hemorrhage and ischemic brain injury in very low birth weight infants. Pediatrics 2003; 111: e497-e503
• 75 Benlamri A, Murthy P, Zein H. et al. Neuroprotection care bundle implementation is associated with improved long-term neurodevelopmental outcomes in extremely premature infants. J Perinatol 2022; 42: 1380-1384
• 76 Mohammad K, Momin S, Murthy P. et al. Impact of quality improvement outreach education on the incidence of acute brain injury in transported neonates born premature. J Perinatol 2022; 42: 1368-1373
• 77 Cho ES, Kim SJ, Kwon MS. et al. The Effects of Kangaroo Care in the Neonatal Intensive Care Unit on the Physiological Functions of Preterm Infants, Maternal-Infant Attachment, and Maternal Stress. J Pediatr Nurs 2016; 31: 430-438
• 78 Gonya J, Ray WC, Rumpf RW. et al. Investigating skin-to-skin care patterns with extremely preterm infants in the NICU and their effect on early cognitive and communication performance: a retrospective cohort study. BMJ Open 2017; 7: e012985
• 79 Smith SW, Ortmann AJ, Clark WW. Noise in the neonatal intensive care unit: a new approach to examining acoustic events. Noise Health 2018; 20: 121-130
• 80 Braid S, Bernstein J. Improved Cognitive Development in Preterm Infants with Shared Book Reading. Neonatal Netw 2015; 34: 10-17
• 81 Shellhaas RA, Burns JW, Hassan F. et al. Neonatal Sleep-Wake Analyses Predict 18-month Neurodevelopmental Outcomes. Sleep 2017; 40: zsx144
• 82 O’Brien K, Robson K, Bracht M. FICare Study Group and FICare Parent Advisory Board. et al. Effectiveness of Family Integrated Care in neonatal intensive care units on infant and parent outcomes: a multicentre, multinational, cluster-randomised controlled trial. Lancet Child Adolesc Health 2018; 2: 245-254
• 83 Chorna O, Filippa M, De Almeida JS. et al. Neuroprocessing Mechanisms of Music during Fetal and Neonatal Development: A Role in Neuroplasticity and Neurodevelopment. Neural Plast 2019; 2019: 3972918
• 84 Forcada-Guex M, Pierrehumbert B, Borghini A. et al. Early dyadic patterns of mother-infant interactions and outcomes of prematurity at 18 months. Pediatrics 2006; 118: e107-e114
• 85 Belfort MB, Anderson PJ, Nowak VA. et al. Breast Milk Feeding, Brain Development, and Neurocognitive Outcomes: A 7-Year Longitudinal Study in Infants Born at Less Than 30 Weeks’ Gestation. J Pediatr 2016; 177: 133-139.e1
• 86 Vohr BR, Poindexter BB, Dusick AM. et al. Beneficial effects of breast milk in the neonatal intensive care unit on the developmental outcome of extremely low birth weight infants at 18 months of age. Pediatrics 2006; 118: e115-e123
• 87 Sullivan G, Vaher K, Blesa M. et al. Breast Milk Exposure is Associated With Cortical Maturation in Preterm Infants. Ann Neurol 2023; 93: 591-603
• 88 Anderson JW, Johnstone BM, Remley DT. Breast-feeding and cognitive development: a meta-analysis. Am J Clin Nutr 1999; 70: 525-535
• 89 Rozé JC, Darmaun D, Boquien CY. et al. The apparent breastfeeding paradox in very preterm infants: relationship between breast feeding, early weight gain and neurodevelopment based on results from two cohorts, EPIPAGE and LIFT. BMJ Open 2012; 2: e000834
• 90 Ballard O, Morrow AL. Human milk composition: nutrients and bioactive factors. Pediatr Clin North Am 2013; 60: 49-74
• 91 Zhou Q, Li M, Wang X. et al. Immune-related microRNAs are abundant in breast milk exosomes. Int J Biol Sci 2012; 8: 118-123
• 92 Picáns-Leis R, Vázquez-Mosquera ME, Pereira-Hernández M. et al. Characterization of the functional component in human milk and identification of the molecular mechanisms undergoing prematurity. Clin Nutr 2025; 44: 178-192
• 93 Piras M, Coni P, Piludu M. et al. Human breast milk cells are positive for the pioneer transcription factor ISL1. Eur Rev Med Pharmacol Sci 2023; 27: 8842-8849
• 94 Blesa M, Sullivan G, Anblagan D. et al. Early breast milk exposure modifies brain connectivity in preterm infants. Neuroimage 2019; 184: 431-439
• 95 Ottolini KM, Andescavage N, Kapse K. et al. Improved brain growth and microstructural development in breast milk-fed very low birth weight premature infants. Acta Paediatr 2020; 109: 1580-1587
• 96 Atayde AMP, Kapoor NR, Cherkerzian S. et al. Lactoferrin intake from maternal milk during the neonatal hospitalization and early brain development among preterm infants. Pediatr Res 2024; 96: 159-164
• 97 Colaizy TT, Poindexter BB, McDonald SA. et al. Neurodevelopmental Outcomes of Extremely Preterm Infants Fed Donor Milk or Preterm Infant Formula: A Randomized Clinical Trial. JAMA 2024; 331: 582-591
• 98 Singh P, Al Mohannadi N, Murugesan S. et al. Unveiling the dynamics of the breast milk microbiome: impact of lactation stage and gestational age. J Transl Med 2023; 21: 784
• 99 Conboy-Stephenson R, Ross RP, Kelly AL. et al. Donor human milk: the influence of processing technologies on its nutritional and microbial composition. Front Nutr 2024; 11: 1468886
• 100 Fu ZY, Huang C, Lei L. et al. The effect of oropharyngeal colostrum administration on the clinical outcomes of premature infants: A meta-analysis. Int J Nurs Stud 2023; 144: 104527
• 101 Keller T, Körber F, Oberthuer A. et al. Intranasal breast milk for premature infants with severe intraventricular hemorrhage-an observation. Eur J Pediatr 2019; 178: 199-206
• 102 Malhotra A. Neurotherapeutic potential of intranasal administration of human breast milk. Pediatr Res 2023; 94: 1872-1873
• 103 Gallipoli A, Unger S, El Shahed A. et al. Outcomes after intranasal human milk therapy in preterm infants with intraventricular hemorrhage. J Perinatol 2025; 45: 202-207
• 104 Hoban R, Gallipoli A, Signorile M. et al. Feasibility of intranasal human milk as stem cell therapy in preterm infants with intraventricular hemorrhage. J Perinatol 2024; 44: 1652-1657
• 105 Lear CA, Lear BA, Davidson JO. et al. Tumour necrosis factor blockade after asphyxia in foetal sheep ameliorates cystic white matter injury. Brain 2023; 146: 1453-1466
• 106 Ohls RK, Ehrenkranz RA, Das A. et al. Neurodevelopmental outcome and growth at 18 to 22 months’ corrected age in extremely low birth weight infants treated with early erythropoietin and iron. Pediatrics 2004; 114: 1287-1291
• 107 Ohls RK, Kamath-Rayne BD, Christensen RD. et al. Cognitive outcomes of preterm infants randomized to darbepoetin, erythropoietin, or placebo. Pediatrics 2014; 133: 1023-1030
• 108 Natalucci G, Latal B, Koller B. et al. Effect of Early Prophylactic High-Dose Recombinant Human Erythropoietin in Very Preterm Infants on Neurodevelopmental Outcome at 2 Years: A Randomized Clinical Trial. JAMA 2016; 315: 2079-2085
• 109 Song J, Sun H, Xu F. et al. Recombinant human erythropoietin improves neurological outcomes in very preterm infants. Ann Neurol 2016; 80: 24-34
• 110 Juul SE, Comstock BA, Wadhawan R. et al. A Randomized Trial of Erythropoietin for Neuroprotection in Preterm Infants. N Engl J Med 2020; 382: 233-243
• 111 Robertson NJ, Tan S, Groenendaal F. et al. Which neuroprotective agents are ready for bench to bedside translation in the newborn infant?. J Pediatr 2012; 160: 544-552.e4
• 112 Drury PP, Davidson JO, Bennet L. et al. Partial neural protection with prophylactic low-dose melatonin after asphyxia in preterm fetal sheep. J Cereb Blood Flow Metab 2014; 34: 126-135
• 113 Marseglia L, Gitto E, Laschi E. et al. Antioxidant Effect of Melatonin in Preterm Newborns. Oxid Med Cell Longev 2021; 2021: 6308255
• 114 Häusler S, Robertson NJ, Golhen K. et al. Melatonin as a Therapy for Preterm Brain Injury: What Is the Evidence?. Antioxidants (Basel) 2023; 12: 1630
• 115 Schmidt B, Roberts RS, Davis P. et al. Caffeine therapy for apnea of prematurity. N Engl J Med 2006; 354: 2112-2121
• 116 Back SA, Craig A, Luo NL. et al. Protective effects of caffeine on chronic hypoxia-induced perinatal white matter injury. Ann Neurol 2006; 60: 696-705
• 117 McLeod RM, Rosenkrantz TS, Fitch RH. et al. Sex Differences in Microglia Activation in a Rodent Model of Preterm Hypoxic Ischemic Injury with Caffeine Treatment. Biomedicines 2023; 11: 185
• 118 Alexander M, Smith AL, Rosenkrantz TS. et al. Therapeutic effect of caffeine treatment immediately following neonatal hypoxic-ischemic injury on spatial memory in male rats. Brain Sci 2013; 3: 177-190
• 119 Kilicdag H, Daglioglu YK, Erdogan S. et al. Effects of caffeine on neuronal apoptosis in neonatal hypoxic-ischemic brain injury. J Matern Fetal Neonatal Med 2014; 27: 1470-1475
• 120 Schmidt B, Roberts RS, Davis P. et al. Long-term effects of caffeine therapy for apnea of prematurity. N Engl J Med 2007; 357: 1893-1902
• 121 Smith MJ, Paton MCB, Fahey MC. et al. Neural stem cell treatment for perinatal brain injury: A systematic review and meta-analysis of preclinical studies. Stem Cells Transl Med 2021; 10: 1621-1636
• 122 Passera S, Boccazzi M, Bokobza C. et al. Therapeutic potential of stem cells for preterm infant brain damage: Can we move from the heterogeneity of preclinical and clinical studies to established therapeutics?. Biochem Pharmacol 2021; 186: 114461
• 123 Malhotra A, Novak I, Miller SL. et al. Autologous transplantation of umbilical cord blood-derived cells in extreme preterm infants: protocol for a safety and feasibility study. BMJ Open 2020; 10: e036065

Publication History

Received: 23 January 2025

Accepted after revision: 12 March 2025

Article published online:
30 June 2025