Key words
assisted reproductive technology (ART) - pregnancy - spontaneous conception - pregnancy
outcome - twins
Schlüsselwörter
assistierte Reproduktion - Schwangerschaft - Spontankonzeption - Ausgang der Schwangerschaft
- Zwillinge
Introduction
In the last decade, the number of multiple pregnancies occurring worldwide has increased.
The main contributors to this rise include increasing maternal age and the use of
ovulation stimulation in assisted reproductive technologies (ART). There is an ongoing
debate about the risk of twin pregnancies after assisted reproduction. Dual embryo
transfer has been the standard for many years [1]. It is estimated that pregnancies resulting from ART procedures account for 0.2–3.9 %
of births in Europe [2]. Attitudes toward multiple pregnancies and pregnancy complications differ between
infertile and fertile women. Patients who are treated for infertility with ART usually
have a greater desire for twins in order to increase the success rate of ART [3]. Risks associated with multiple pregnancies are more acceptable to infertile women,
and only a quarter of infertile patients agree to the transfer of only one embryo
[1]. Careful monitoring and management of twin pregnancies is the basis of modern perinatology
because multiple pregnancies carry an increased risk of perinatal
morbidity and mortality compared with singleton pregnancies [2]. This risk is the result of complications such as premature birth, fetal growth
restriction, preeclampsia, etc. [4], [5]. ART twins have considerably higher risks compared to ART singletons with regard
to most short and long-term outcomes [6], [7]. Thus, high twin birth rates and adverse outcomes in twins are still a major concern
in ART [1]. However, previous studies have shown that twins conceived by ART have similar physical
and neurological development to those of twins conceived naturally. Moreover, the
incidence of pregnancy complications in multiple pregnancies was found to be comparable,
irrespective of the method of conception [2], [8].
The aim of this study was to investigate the course and outcomes of twin pregnancies
conceived by assisted reproduction (ART) compared to twin pregnancies conceived spontaneously.
Materials and Methods
Recruitment of study population
The study involved patients with twin pregnancies who delivered at the Clinic of Gynecology
and Obstetrics, Clinical Center of Serbia between January 1, 2011 and December 31,
2013. Patients were divided into two groups according to the method of conception
(spontaneous or ART).
Assessment of clinical data
Age, parity, illnesses in pregnancy and type/nature of the illness (hypertension [HTA],
diabetes mellitus [DM], placental abruption or placenta praevia, other diseases and
simultaneous associated comorbidities), etiology of infertility (male, tubal, ovarian
insufficiency, endometriosis, immunological, unknown and combined), time of membrane
rupture (spontaneous premature preterm rupture of membranes [PPROM] or rupture in
hospital after the start of contractions) and type of delivery (vaginal or cesarean)
were recorded for each patient. Type of ART (only in vitro fertilization [IVF], IVF/ICSI
[intracytoplasmic sperm injection] or IUI [intrauterine insemination]) was also noted
for each patient.
Weeks of gestation at delivery, presentation, gender, weight, Apgar score, chorionicity
and morbidity (intrauterine growth restriction [IUGR], malformations, asphyxiation,
comorbidities and other disorders) were recorded for each twin. Pregnancy outcome
was considered excellent if both twins had Apgar scores above eight (Apgar I + Apgar
II > 16), intermediate if Apgar I + Apgar II was between 10 and 16, while the outcome
was considered bad if Apgar I + Apgar II was < 10.
The data were compared between the groups of patients with and without ART as well
as between the types of ART. Every patient gave informed consent for all procedures
upon admission to the Clinic. The study was approved by the Clinic Board.
Statistical analysis
Statistical analysis was done using descriptive and analytical statistics (percentages,
χ2 test, Kruskal-Wallis test and correlations) using the SPSS program, version 15. Binary
logistic regression was done to test for a possible relationship between assessed
characteristics of mothers and twins and conception by ART. Finally, Receiver Operator
Curve (ROC) analysis was performed for parameters that correlated significantly with
ART use for conception.
Results
Characteristics of investigated women
Parameters of pregnant women and their pregnancies for the overall group and according
to type of conception (spontaneous, ART) are presented in [Table 1]. The same parameters differentiated according to ART type are shown in [Table 2].
Table 1 Parameters of pregnant women and their pregnancies for the overall group and according
to type of conception (spontaneous, ART).
|
Parameters
|
Whole group
|
ART
|
|
No
|
Yes
|
|
Number
|
%
|
Number
|
%
|
Number
|
%
|
|
ART: assisted reproductive technology; PPROM: premature preterm rupture of membranes;
CS: cesarean section
|
|
Parity
|
1
|
335
|
77.7
|
120
|
27.84
|
215
|
49.88
|
|
2
|
68
|
15.8
|
51
|
11.83
|
17
|
3.94
|
|
3
|
15
|
3.5
|
14
|
3.25
|
1
|
0.23
|
|
more
|
13
|
3.1
|
13
|
3.02
|
0
|
0.00
|
|
Cause of infertility
|
male
|
67
|
28.7
|
0
|
0.00
|
67
|
28.76
|
|
tubal
|
53
|
22.7
|
0
|
0.00
|
53
|
22.75
|
|
immunologic
|
4
|
1.7
|
0
|
0.00
|
4
|
1.72
|
|
ovarian insufficiency
|
5
|
2.1
|
0
|
0.00
|
5
|
2.15
|
|
endometriosis
|
25
|
10.7
|
0
|
0.00
|
25
|
10.73
|
|
combined
|
36
|
15.5
|
0
|
0.00
|
36
|
15.45
|
|
unknown
|
43
|
18.5
|
0
|
0.00
|
43
|
18.45
|
|
PPROM
|
no
|
327
|
75.9
|
157
|
36.43
|
170
|
39.44
|
|
yes
|
104
|
24.1
|
41
|
9.51
|
63
|
14.62
|
|
Amniotic fluid
|
clear
|
399
|
92.6
|
187
|
43.39
|
212
|
49.19
|
|
not clear
|
32
|
7.4
|
11
|
2.55
|
21
|
4.87
|
|
Delivery type
|
vaginal
|
175
|
40.6
|
146
|
33.87
|
29
|
6.73
|
|
planned CS
|
149
|
34.6
|
30
|
6.96
|
119
|
27.61
|
|
urgent CS
|
107
|
24.8
|
22
|
5.10
|
85
|
19.72
|
|
Maternal comorbidities
|
none
|
243
|
56.4
|
110
|
25.52
|
133
|
30.86
|
|
hypertension
|
58
|
13.5
|
31
|
7.19
|
27
|
6.26
|
|
diabetes
|
21
|
4.9
|
5
|
1.16
|
16
|
3.71
|
|
placental
|
8
|
1.9
|
4
|
0.93
|
4
|
0.93
|
|
other
|
64
|
14.8
|
31
|
7.19
|
33
|
7.66
|
|
multiple
|
37
|
8.6
|
17
|
3.94
|
20
|
4.64
|
|
Supportive therapy
|
no
|
45
|
10.4
|
22
|
5.10
|
23
|
5.34
|
|
progesterone
|
6
|
1.4
|
1
|
0.23
|
5
|
1.16
|
|
antibiotics
|
25
|
5.8
|
12
|
2.78
|
13
|
3.02
|
|
combined
|
284
|
65.9
|
127
|
29.47
|
157
|
36.43
|
|
other
|
71
|
16.5
|
36
|
8.35
|
35
|
8.12
|
|
Cerclage
|
no
|
379
|
87.9
|
172
|
39.91
|
207
|
48.03
|
|
yes
|
52
|
12.1
|
26
|
6.03
|
26
|
6.03
|
Table 2 Parameters of pregnant women and their pregnancies differentiated according to type
of ART.
|
Parameters
|
ART type
|
|
IVF
|
IVF/ICSI
|
IUI
|
|
Number
|
%
|
Number
|
%
|
Number
|
%
|
|
ART: assisted reproductive technology; IVF: in vitro fertilization; ICSI: intracytoplasmic
sperm injection; IUI: intrauterine insemination; PPROM: premature preterm rupture
of membranes; CS: cesarean section
|
|
Parity
|
1
|
55
|
23.61
|
150
|
64.38
|
10
|
4.29
|
|
2
|
4
|
1.72
|
13
|
5.58
|
0
|
0.00
|
|
3
|
0
|
0.00
|
1
|
0.43
|
0
|
0.00
|
|
more
|
0
|
0.00
|
0
|
0.00
|
0
|
0.00
|
|
Cause of infertility
|
male
|
14
|
6.01
|
50
|
21.46
|
3
|
1.29
|
|
tubal
|
22
|
9.44
|
27
|
11.59
|
4
|
1.72
|
|
immunologic
|
0
|
0.00
|
4
|
1.72
|
0
|
0.00
|
|
ovarian insufficiency
|
0
|
0.00
|
4
|
1.72
|
1
|
0.43
|
|
endometriosis
|
5
|
2.15
|
19
|
8.15
|
1
|
0.43
|
|
combined
|
7
|
3.00
|
29
|
12.45
|
0
|
0.00
|
|
unknown
|
11
|
4.72
|
31
|
13.30
|
1
|
0.43
|
|
PPROM
|
no
|
41
|
17.60
|
125
|
53.65
|
4
|
1.72
|
|
yes
|
18
|
7.73
|
39
|
16.74
|
6
|
2.58
|
|
Amniotic fluid
|
clear
|
53
|
22.75
|
151
|
64.81
|
8
|
3.43
|
|
not clear
|
6
|
2.58
|
13
|
5.58
|
2
|
0.86
|
|
Delivery type
|
vaginal
|
7
|
3.00
|
20
|
8.58
|
2
|
0.86
|
|
planned CS
|
29
|
12.45
|
86
|
36.91
|
4
|
1.72
|
|
urgent CS
|
23
|
9.87
|
58
|
24.89
|
4
|
1.72
|
|
Maternal comorbidities
|
none
|
32
|
13.73
|
94
|
40.34
|
7
|
3.00
|
|
hypertension
|
9
|
3.86
|
16
|
6.87
|
2
|
0.86
|
|
diabetes
|
3
|
1.29
|
13
|
5.58
|
0
|
0.00
|
|
placental
|
0
|
0.00
|
3
|
1.29
|
1
|
0.43
|
|
other
|
12
|
5.15
|
21
|
9.01
|
0
|
0.00
|
|
multiple
|
3
|
1.29
|
17
|
7.30
|
0
|
0.00
|
|
Supportive therapy
|
no
|
7
|
3.00
|
14
|
6.01
|
2
|
0.86
|
|
progesterone
|
2
|
0.86
|
3
|
1.29
|
0
|
0.00
|
|
antibiotics
|
7
|
3.00
|
6
|
2.58
|
0
|
0.00
|
|
combined
|
37
|
15.88
|
113
|
48.50
|
7
|
3.00
|
|
other
|
6
|
2.58
|
28
|
12.02
|
1
|
0.43
|
|
Cerclage
|
no
|
55
|
23.61
|
143
|
61.37
|
9
|
3.86
|
|
yes
|
4
|
1.72
|
21
|
9.01
|
1
|
0.43
|
The study included 431 patients with twin pregnancies. The mean age of the women was
32.99 ± 6.46 years (minimum = 17 years; maximum = 43 years). The majority of women
were primiparous. The most frequent cause of infertility was male.
Delivery time and mode
Delivery mostly occurred in the 36th gestational week (minimum = 25; maximum = 40;
mean ± SD = 35.42 ± 2.80). Only 18 patients delivered before the 30th gestational
week. 33.2 % of women gave birth after the 38th gestational week. Although more women
had cesarean sections, the incidence of planned and urgent operative deliveries was
similar.
Pregnancy complications and treatment
Hypertensive disorders were the most common, but the majority of mothers had no pregnancy-related
disease. Only a few women (n = 30) had pre-existing medical conditions, mostly diabetes.
However, more than half of the patients received a combined therapy for pregnancy
support, and almost 90 % of women received some kind of medication during pregnancy.
Preterm membrane rupture was relatively rare and amniotic fluid was usually normal.
Cerclage and maturation of fetal lungs were usually not done.
Characteristics of assessed twins
Parameters of twins for the whole group and differentiated according to method of
conception (spontaneous, ART) are shown in [Table 3]. Parameters of twins differentiated according to type of ART are given in [Table 4].
Table 3 Parameters of twins for the whole group and according to type of conception (spontaneous,
ART).
|
Parameters
|
Whole group
|
ART
|
|
No
|
Yes
|
|
Number
|
%
|
Number
|
%
|
Number
|
%
|
|
IUGR: intrauterine growth restriction; ART: assisted reproductive technology
|
|
I twin presentation
|
head
|
268
|
62.2
|
122
|
28.31
|
146
|
33.87
|
|
pelvis
|
142
|
32.9
|
66
|
15.31
|
76
|
17.63
|
|
other
|
21
|
4.9
|
10
|
2.32
|
11
|
2.55
|
|
II twin presentation
|
head
|
222
|
51.5
|
97
|
22.51
|
125
|
29.00
|
|
pelvis
|
107
|
24.8
|
52
|
12.06
|
55
|
12.76
|
|
other
|
102
|
23.7
|
49
|
11.37
|
53
|
12.30
|
|
I twin gender
|
male
|
226
|
52.4
|
105
|
24.36
|
121
|
28.07
|
|
female
|
205
|
47.6
|
93
|
21.58
|
112
|
25.99
|
|
II twin gender
|
male
|
203
|
47.1
|
95
|
22.04
|
108
|
25.06
|
|
female
|
228
|
52.9
|
103
|
23.90
|
125
|
29.00
|
|
Twins comorbidities
|
none
|
360
|
83.5
|
163
|
37.82
|
197
|
45.71
|
|
malformations
|
16
|
3.7
|
9
|
2.09
|
7
|
1.62
|
|
IUGR
|
3
|
0.7
|
2
|
0.46
|
1
|
0.23
|
|
asphyxiation
|
13
|
3.0
|
6
|
1.39
|
7
|
1.62
|
|
multiple
|
11
|
2.6
|
4
|
0.93
|
7
|
1.62
|
|
other
|
28
|
6.5
|
14
|
3.25
|
14
|
3.25
|
|
Maturation
|
no
|
345
|
80.0
|
157
|
36.43
|
188
|
43.62
|
|
yes
|
86
|
20.0
|
41
|
9.51
|
45
|
10.44
|
|
Chorionicity
|
dichorionic
|
404
|
93.7
|
190
|
44.08
|
214
|
49.65
|
|
monochorionic
|
27
|
6.3
|
8
|
1.86
|
19
|
4.41
|
|
Outcome
|
excellent
|
208
|
25.1
|
99
|
22.97
|
109
|
25.29
|
|
intermediate
|
157
|
19.0
|
64
|
14.85
|
93
|
21.58
|
|
bad
|
66
|
8.0
|
35
|
8.12
|
31
|
7.19
|
Table 4 Frequency of assessed parameters of twins concerning ART type.
|
Parameters
|
ART type
|
|
IVF
|
IVF/ICSI
|
IUI
|
|
Number
|
%
|
Number
|
%
|
Number
|
%
|
|
IUGR: intrauterine growth restriction; IVF: in vitro fertilization; ICSI: intracytoplasmic
sperm injection; IUI: intrauterine insemination
|
|
I twin presentation
|
head
|
39
|
16.74
|
102
|
43.78
|
5
|
2.15
|
|
pelvis
|
17
|
7.30
|
54
|
23.18
|
5
|
2.15
|
|
other
|
3
|
1.29
|
8
|
3.43
|
0
|
0.00
|
|
II twin presentation
|
head
|
37
|
15.88
|
82
|
35.19
|
6
|
2.58
|
|
pelvis
|
14
|
6.01
|
38
|
16.31
|
3
|
1.29
|
|
other
|
8
|
3.43
|
44
|
18.88
|
1
|
0.43
|
|
I twin sex
|
male
|
32
|
13.73
|
84
|
36.05
|
5
|
2.15
|
|
female
|
27
|
11.59
|
80
|
34.33
|
5
|
2.15
|
|
II twin sex
|
male
|
31
|
13.30
|
71
|
30.47
|
6
|
2.58
|
|
female
|
28
|
12.02
|
93
|
39.91
|
4
|
1.72
|
|
Twins comorbidities
|
none
|
49
|
21.03
|
140
|
60.09
|
8
|
3.43
|
|
malformations
|
0
|
0.00
|
6
|
2.58
|
1
|
0.43
|
|
IUGR
|
0
|
0.00
|
1
|
0.43
|
0
|
0.00
|
|
asphyxiation
|
4
|
1.72
|
2
|
0.86
|
1
|
0.43
|
|
multiple
|
3
|
1.29
|
4
|
1.72
|
0
|
0.00
|
|
other
|
3
|
1.29
|
11
|
4.72
|
0
|
0.00
|
|
Maturation
|
no
|
46
|
19.74
|
135
|
57.94
|
7
|
3.00
|
|
yes
|
13
|
5.58
|
29
|
12.45
|
3
|
1.29
|
|
Chorionicity
|
dichorionic
|
59
|
25.32
|
145
|
62.23
|
10
|
4.29
|
|
monochorionic
|
0
|
0.00
|
19
|
8.15
|
0
|
0.00
|
|
Outcome
|
excellent
|
24
|
10.30
|
80
|
34.33
|
5
|
2.15
|
|
intermediate
|
28
|
12.02
|
63
|
27.04
|
2
|
0.86
|
|
bad
|
7
|
3.00
|
21
|
9.01
|
3
|
1.29
|
The majority of both first and second twins were in head presentation. The first twins
were mostly male and the second twins were often female, but overall, there was a
similar number of twins of both sexes. There were considerably more dichorionic twins
irrespective of the method of conception.
Twinsʼ condition and outcome
The majority of twins were in good condition. Only a few twins had illnesses or other
complications during pregnancy. There were four stillbirths (one naturally conceived
and three conceived by IVF/ICSI). Mean birth weight of the first twins was 2331.53 ± 591.29 g
(minimum = 460; maximum = 3840 g) and of the second twins was 2257.27 ± 604.44 g (minimum = 300;
maximum = 3500 g).
Average Apgar score of the first twins was 7.11 ± 2.06 while for the second twins
it was 7.04 ± 2.06. In most cases, both twins (over 50 %) had a good Apgar score (above
eight). Thus, the majority of twins had excellent pregnancy outcomes, regardless of
the conception method. Poor pregnancy outcomes were recorded more frequently for naturally
conceived twins.
Conception method
The rate of twins conceived by ART was slightly higher (n = 233; 54.1 %). The most
common type of ART used was IVF/ICSI (n = 164; 38.1 %), while IUI was rare (n = 10;
2.3 %).
Correlations between parameters and conception method
Both the use of ART and the type of method used were significantly positively correlated
with maternal age and delivery type. Women who required more sophisticated ART methods
were older (ρ = 0.319; p < 0.001) and were delivered by cesarean section, usually
planned (ρ = 0.523; p < 0.001). However, as expected, there was a significant negative
correlation with parity (ρ = −0.364; p < 0.001), since women suffering from infertility
usually conceived using ART. Conception by ART was associated with dichorionicity
(ρ = −0.100; p = 0.036). There were no other significant correlations between ART
use or type and the other evaluated characteristics of mothers and twins (infertility
cause, comorbidities of mothers and twins, treatment, cerclage, pregnancy outcome,
fetal lung maturation, fetal gender, etc.).
Differences in parameters with regard to conception method
Regarding the use of ART, there were significant differences in patient age (KWχ2 = 55.909; p < 0.001) and parity (KWχ2 = 64.600; p < 0.001) as well as delivery type (KWχ2 = 136.658; p < 0.001). When we assessed the type of ART procedure, significant differences
were found for PPROM (KWχ2 = 6.721; p = 0.035) and patient age (KWχ2 = 10.485; p = 0.005). Patients who had ICSI were older and PPROM was more common.
Dichorionic twins were mostly conceived by ART and had better survival rates (KWχ2 = 4.370; p = 0.037). Monochorionic twins were conceived either spontaneously or using
ICSI. There were no other significant differences between patients who conceived using
ART or spontaneously or between ART types with regard to characteristics of mothers
and twins and overall outcome of pregnancy.
Relationship model and ROC analysis
A significant logistic regression equation for the relationship between assessed characteristics
of mothers and twins and conception using ART was obtained (χ2 = 224.820; p = 0.001; total classification = 84.9 %). Based on the equation it was
found that advanced maternal age, the presence of comorbidities and lower parity were
the most important predictors for ART conception. Additionally, twins conceived by
ART were more likely to have PPROM and be delivered by cesarean section.
According to results of the ROC analysis, maternal age correctly explained the use
of ART for the conception of twins in 70.8 % of cases, parity in 33.7 %, chorionicity
in 48.7 %, and predicted that ART twins would be delivered by cesarean section in
80.6 % of cases ([Fig. 1]). When an age of 32.5 years was taken as the cut-off value, the sensitivity of ART
use for conception of twins was 68.2 %, the specificity was 63.1 %, the positive predictive
value was 53.2 % and the negative predictive value was 71.6 %.
Fig. 1 ROC analysis of maternal age, parity, chorionicity and type of delivery for the prediction
of ART conception of twins.
Discussion
Based on our results it can be stated that the use of ART for conception does not
have a significant negative influence on twin pregnancy outcomes. Maternal age, comorbidities
and parity all influence the decision to use ART for conception. We have shown that
uncomplicated twin pregnancies with successful delivery at term are possible, although
currently the majority of twins conceived by ART are delivered by cesarean section.
The literature on the outcome of twin pregnancies, including meta-analyses, has been
contradictory [9]. While some studies suggest that twins conceived by ART have a higher risk of pregnancy
complications, premature birth, low birth weight, and mortality at birth, other studies
argue that there is no evidence of a higher incidence of adverse outcomes [10].
Several previous investigations have shown that obstetrical outcomes in ART pregnancies
are worse than in the general population, which can be mainly explained by the higher
multiple birth rates after ART, which account for the most severe obstetric outcomes
[9]. Some researchers, after controlling for maternal age and nulliparity, have provided
evidence that twin pregnancies conceived using ART and ovulation induction have an
increased risk of gestational diabetes mellitus. The most common complications of
pregnancies after ART are bleeding in the first trimester and disproportionate growth
of twins [11]. In addition, IVF-conceived pregnancies have been associated with a higher incidence
of preterm births and prematurity-related respiratory complications with longer stays
in the neonatal intensive care unit [12], [13].
Conversely, our study found no significant differences with regard to pregnancy complications
between groups with and without ART. Other researchers have also claimed that, although
some antenatal complications are more common in ART twins than in spontaneously conceived
twins, the overall prevalence of complications is low and thus their impact on the
morbidity and mortality of an individual pregnancy is limited. Pregnancy complications
do not contribute to higher rates of premature rupture of membranes or the frequency
of IUGR in ART twin pregnancies [12], [13]. In our population, although delivery mostly occurred during the 36th gestational
week, PPROM was also not common. However, PPROM was more common if ICSI was used for
conception. Moreover, some data show that the rate of preterm births is similar to
that of spontaneously conceived twins and that very preterm deliveries even occurred
more frequently with spontaneously conceived twin pregnancies [14], [15]. It is possible that women with an IVF pregnancy were more compliant with therapy
and more likely
to take early work leave, both of which could have a positive effect on preventing
preterm labor. Hence, in healthy women younger than 45 years of age, twin pregnancies
after ART do not require additional antenatal care compared with spontaneously conceived
twins [16], [17], [18].
The increased risk of congenital malformations associated with ART was not significant
in different studies after adjusting for confounding parental factors [19]. We also found that there were no significant malformations in twins as a result
of ART procedures.
Our results suggest that twin pregnancies conceived by ART have similar outcomes for
both mother and child to outcomes after spontaneously conceived pregnancies, which
is consistent with findings in the majority of other studies [19]. We found no difference in birth weight of the first and second twin between groups
with and without ART, which is in agreement with other studies [10]. Our findings showed no significant difference in mortality or general condition
at birth between twins conceived using ART methods or spontaneously. The majority
of twins were in good condition, complications were rare, and the twins usually had
an Apgar score ≥ 8. There were no significant correlations between ART and the evaluated
characteristics of twins.
The risk profiles for ART twins and two consecutive ART singletons can be assumed
to be very similar. Moreover, the overall consensus, with few exceptions, is that
ART twins have neonatal outcomes that are similar to those of infants conceived spontaneously.
Some literature reviews reported that ART twins had even better outcomes than spontaneously
conceived twins. This might be due to mothers with spontaneously conceived twins having
fewer regular check-ups compared to mothers with ART-conceived twins. Studies reported
that uncomplicated twin pregnancies with successful delivery at term are possible
[20]. This was also confirmed by our study. Therefore, it can be stated that twin pregnancies
represent an entirely reasonable option for IVF patients [21].
It remains unclear whether the increased risk of adverse obstetric outcomes after
ART is a direct effect of the procedure and the technology or whether it reflects
some other factor related to the underlying infertility of the couple. If the problem
lies in the ART technology itself, more adverse outcomes would be documented for ART
twins, but this has not been the case so far. Some data, including our findings, show
that the increased risk for adverse pregnancy outcomes does not depend on the type
of ART procedure. These results suggest that perhaps underlying factors associated
with the motherʼs infertility exert more negative effects on children than the ART
procedure itself [12], [22].
The literature shows that mothers of twins conceived using ART are usually significantly
older [23]. This was also the case in our study. However, this observation may indicate a potential
bias with regard to maternal age and the number of embryos transferred, since older
women are more likely to desire twin pregnancies. Moreover, almost all mothers in
different studies were under the age of 40, and therefore overall study populations
are young. This is also due to the fact that there is usually an age limit for performing
ART procedures [19].
In some populations, the rate of cesarean sections was slightly, but not significantly,
higher in ART pregnancies. In the majority of studies, the most common indication
for cesarean section is the presentation of the first twin [13]. In our population, the incidence of cesarean sections was also higher compared
to vaginal deliveries, but there was no difference with regard to the method of ART
used. In our study cohort, most twins were in head presentation, irrespective of the
delivery method. In spontaneously conceived pregnancies, cesarean sections were often
done because of a previous operative delivery, whereas ART pregnancies were usually
the first pregnancy. The majority of our patients were also primiparas. Although most
women did not have any pregnancy-related morbidities, almost 90 % received some kind
of medication during pregnancy. The increased incidence of cesarean sections and the
multiple medications may be due to the patientʼs and/or physicianʼs concerns regarding
pregnancy outcome rather than obstetric indications [15], [23].
Finally, it should be noted that this study has some limitations. We did not assess
fetal losses in the first trimester. In this investigation we focused on pregnancies
that lasted more than 30 gestational weeks. Pregnancies terminated before that period
are not currently sufficiently numerous to be analyzed. Further research in this area
might be possible in a few years. Our study created an equation showing the relationship
between assessed maternal and twin characteristics and the use of ART procedures for
conception.
Conclusions
Maternal age, illnesses and parity can influence the decision whether to use ART for
conception. Older women suffering from infertility need more sophisticated ART methods
to conceive and generally take multiple medications during pregnancy. Our results
suggest that twin pregnancies conceived by ART methods have similar outcomes for both
mother and child to those of spontaneously conceived pregnancies. The use of ART for
conception does not have a significant negative influence on twin pregnancy outcomes.
If IVF/ICSI is used, PPROM is more frequent, and cesarean section is usually the method
of delivery for these patients. However, preterm delivery is infrequent irrespective
of the conception method. The majority of twins had favorable pregnancy outcomes and
good Apgar scores, and complications were rare. Our findings suggest that the transfer
of two embryos is safe. Uncomplicated twin pregnancies with successful delivery at
term are possible, and ART twins do not require additional antenatal care compared
to spontaneously conceived twins.
