Abstract
Objective Idiopathic polyhydramnios is among the most common etiologies of polyhydramnios.
However, conflicting evidence exists regarding the relationship between polyhydramnios
and neonatal morbidity. We investigated the association between pregnancies with and
without idiopathic polyhydramnios and neonatal morbidity at term.
Study Design This is a retrospective cohort study of singleton, term (i.e., ≥370/7 weeks) pregnancies from 2014 to 2018. Pregnancies complicated by fetal anomalies,
pregestational diabetes, and multifetal gestation were excluded. Pregnancies complicated
by idiopathic polyhydramnios were defined by the deepest vertical pocket (DVP) ≥8 cm
or amniotic fluid index (AFI) ≥24 cm after 20 weeks' gestation and were compared with
women without polyhydramnios at time of delivery. These groups were matched 1:2 by
gestational age within 7 days at delivery and maternal race. The primary outcome was
a composite neonatal morbidity (neonatal death, respiratory morbidity, hypoxic–ischemic
encephalopathy, therapeutic hypothermia, seizures, and umbilical artery pH < 7.10).
Outcomes were compared between pregnancies with and without idiopathic polyhydramnios.
Unadjusted and adjusted risk ratios were estimated using multivariable logistic regression.
Results Idiopathic polyhydramnios was diagnosed in 192 pregnancies and were matched to 384
pregnancies without polyhydramnios. After adjustment for obesity, women with pregnancies
complicated by idiopathic polyhydramnios had an increased risk of composite neonatal
morbidity 21.4 versus 5.5% (adjusted risk ratio [aRR] = 4.0, 95% confidence interval
[CI]: 2.3–6.7). Term neonatal respiratory morbidity was the primary driver 20.3 versus
4.2%, (aRR = 4.8, 95% CI: 2.7–8.7) and included higher use of continuous positive
airway pressure 19.8 versus 3.4%, p <0.01 and the need for supplemental oxygen at >12 hours of newborn life 6.8 versus
1.8%, p <0.01.
Conclusion Idiopathic polyhydramnios is associated with term neonatal respiratory morbidity
at delivery and during the subsequent hours of newborn life, compared with pregnancies
without idiopathic polyhydramnios. Further studies are needed to minimize neonatal
morbidity at term.
Key Points
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Idiopathic polyhydramnios is associated with increased risk of neonatal morbidity
at term.
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Increasing idiopathic polyhydramnios severity was associated with a trend toward worsening
morbidity at term.
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Idiopathic polyhydramnios at term requires respiratory support at delivery and during
neonatal care.
Keywords
neonatal morbidity - polyhydramnios - respiratory morbidity
