Am J Perinatol 2024; 41(S 01): e1390-e1396
DOI: 10.1055/a-2023-8813
Original Article

Investigating Relations between the NICU Speech Environment and Weight Gain in Infants Born Very Preterm

Komal Kumar
1   Division of Neonatal and Developmental Medicine, Department of Pediatrics, Stanford University, Stanford, California
Virginia A. Marchman
2   Department of Psychology, Stanford University, Stanford, California
3   Division of Developmental-Behavioral Pediatrics, Department of Pediatrics, Stanford University, Stanford, California
Maya C. Morales
3   Division of Developmental-Behavioral Pediatrics, Department of Pediatrics, Stanford University, Stanford, California
Melissa Scala*
1   Division of Neonatal and Developmental Medicine, Department of Pediatrics, Stanford University, Stanford, California
3   Division of Developmental-Behavioral Pediatrics, Department of Pediatrics, Stanford University, Stanford, California
› Author Affiliations
Funding This research work was supported by grants from the U.S. Department of Health and Human Services, National Institutes of Health—Eunice Kennedy Shriver National Institute of Child Health and Human Development (K.E.T., PI; 5R00HD8474904), Stanford Maternal Child Health Research Institute grant.


Objective Children born preterm, especially those born very preterm (<32 weeks of gestational age [GA]) are at risk for poor growth and adverse neurodevelopmental outcomes. Adverse growth and neurodevelopmental outcomes in preterm children have been attributed, in part, to the aversive sounds and relative speech paucity of the neonatal intensive care unit (NICU). Experimental studies that directly expose preterm infants to speech sounds in the NICU find significant improvements in health factors relevant to neurodevelopment. Few studies have examined whether natural variations in the speech environment of the NICU are related to short-term health outcomes in preterm infants. Such data are important for optimizing the sound environment of the NICU. Our objective was to examine relations between the NICU speech environment and the rate of weight gain during hospitalization.

Study Design Participants were infants born very preterm (n = 20). The speech environment of each infant was assessed at 32 to 36 weeks of postmenstrual age using an automatic speech-counting device. Average rates of weight gain (g/kg/d) were ascertained over the same period. Calories were derived from charted intake (kcals/kg/d). Linear regressions examined caloric intake and speech counts as predictors of infant weight gain.

Results Infant weight gain was significantly predicted by caloric intake and speech exposure, each uniquely accounting for approximately 27% variance (total R 2 = 60.2%; p < 0.001). Speech counts were uncorrelated with rates of family visitation, time in incubator, or health acuity.

Conclusion While future research should establish causality and direction of effects, enhancing speech exposure in the NICU may be beneficial for physical growth. NICU care plans should consider opportunities to increase speech exposure.

Key Points

  • Preterm infants who experienced greater amounts of speech in the NICU gained significantly more weight than preterm infants who were exposed to lower amounts of speech during the same developmental period (32–36 weeks of postmenstrual age).

  • Caloric intake and speech counts accounted for almost 60% of variance in infant weight gain between 32 and 36 weeks of postmenstrual age.

  • Speech counts were not significantly correlated with family visitation, how long infants resided in incubators, or health acuity.

  • Findings suggest that the NICU speech environment may play an important role in the physical health of preterm infants; however, more studies are needed to determine the directionality of the observed associations.


A version of this study was previously submitted as a preprint to medRxiv.[27]

* equally contributing senior authors.

Publication History

Received: 02 September 2022

Accepted: 30 January 2023

Accepted Manuscript online:
31 January 2023

Article published online:
14 March 2023

© 2023. Thieme. All rights reserved.

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