Interpretation
Twin pregnancies are at a higher risk for gestational diabetes than
singleton pregnancies, every additional fetus in multiple pregnancies
increasing the risk for GDM by 1.8 times. Consistent with these studies,
data of this analysis also showed a significant association between
obesity and GDM, with significantly increasing rates within obesity
classes. With GDM increasing the risks for cesarean sections,
preeclampsia, and preterm birth, and considering the increasing rates of
GDM worldwide, prevention and information on the risks of gestational
diabetes should be extended.
Obesity has been established as an important risk factor for surgical
site infections after cesarean sections. Almost a third of severely
obese patients were described to suffer from wound complications after a
cesarean section. This study confirms these findings, showing an
association between maternal weight in general and especially obesity
and wound complications. Furthermore, Olsen et al. and Wall et al.
showed that missing antibiotic prophylaxis is an independent risk factor
for wound infections and that patients with vertical skin incisions have
a significantly increased incidence of wound complications. At the
Buergerhospital Frankfurt, all cesarean sections are performed under
antibiotic prophylaxis with a transverse skin incision, possibly
explaining the low rates of wound healing disorders in our study.
PPH is the most important reason for pregnancy-related morbidity, 70%
of all PPH being caused by uterine atony or inadequate uterine
contraction. Maternal obesity and multiple pregnancies are considered
being important risk factors for PPH, multifetal gestations possibly
leading into uterine overdistension, and consequently into uterine atony
with the risk of PPH. To our knowledge, this study was the first to
assess the direct influence of maternal weight on uterine atony both
with the necessity of Sulprostone and intervention with a Bakri Balloon
in twin pregnancies. In contrast to the studies mentioned afore, rates
of PPH did not reach significance in this study, however, women with
obesity class I had a threefold risk for PPH compared to obesity class
II and a twofold risk for PPH compared to obesity class III.
Paidas Teefey et al. investigated rates of cesarean deliveries
especially for obesity class III women in singleton pregnancies, finding
rates of nearly 50% for obesity class III women and 66% for women with
a BMI of at least 50 kg/m2. Albeit not statistically
significant, this study confirmed these findings, showing that cesarean
sections were more common with rising BMI, especially in the obese
group.
Despite being a study conducted in singleton pregnancies and thus only
partially applicable to twins, Bicocca et al. observed a higher risk for
hypertensive pregnancy disorders, including preeclampsia, with
increasing obesity classes. In twin pregnancies, findings on
preeclampsia are inconsistent. On one hand, a BMI
≥30 kg/m2 is considered as a significant risk factor
for preeclampsia, on the other hand, the risk for preeclampsia might
only be significantly increased in obesity class III. Potentially due to
low rates of preeclampsia in this study population, findings of this
study contrast the studies mentioned afore, showing no significant
risks.
In singleton pregnancies, obesity was shown to be the second biggest
risk factor for stillbirth. Similarly, Salihu et al. described a 60%
higher risk for fetal death of both twins in obese women. Both these
findings contrast the results of this study, possibly because of low
rates of IUD in this study in general and similar rates in all weight
groups.
Neonatal outcomes in twin pregnancies have only been investigated in a
few studies, while having been analyzed thoroughly in singleton
pregnancies. Obesity or increasing BMI were shown to be associated with
higher rates of fetomaternal complications as well as admission to NICU
in singleton pregnancies. Confirming these findings, a significantly
higher risk for admission to NICU in neonates of obesity class III
mothers and especially for their firstborn was observed. Maternal weight
did not have an impact on the mean length of stay in the NICU.
Only a few studies have been conducted in twins investigating the topic
of asphyxia and low umbilical artery pH, concluding that the second twin
is at a significantly higher risk for asphyxia, low umbilical artery pH
values or low APGAR scores. To our knowledge, this study is the first
one to assess the impact of maternal weight and obesity on the umbilical
artery pH and asphyxia in twins. Significantly higher rates of pH values
of 7.01 – 7.1 in neonates of obese mothers were observed in this study.
Considering the sparse number of studies on this topic, the impact of
obesity on the risk for asphyxia in twins should be analyzed in further
investigations. Regarding the five-minute APGAR score, our findings
confirmed those of Bautista et al., showing no association between
maternal BMI and a low five-minute APGAR score.