225 Idiopathic polyhydramnios and neonatal morbidity at term: respiratory support at delivery?

Abstract

Idiopathic polyhydramnios (IP) is the most common etiology of polyhydramnios. Yet, conflicting evidence exists regarding the relationship between IP and neonatal morbidity. We investigated the association between IP and neonatal morbidity at term. This is a retrospective cohort of singleton, term pregnancies from 2014-2018. Pregnancies complicated by IP were defined by a deepest vertical pocket (DVP) > 8 cm or amniotic fluid index (AFI) > 24 cm after the 20th week of gestation and were compared to women without polyhydramnios at time of delivery. These groups were matched 1:2 by gestational age within seven 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 IP. The trend with neonatal morbidity by polyhydramnios severity category (mild, moderate, and severe) was assessed using the Cochrane-Armitage test. Unadjusted and adjusted relative risk were estimated using multivariable logistic regression using the Zhang method. IP was diagnosed in 192 pregnancies that were matched to 384 pregnancies without polyhydramnios. After adjustment for obesity, women with pregnancies complicated by IP had an increased risk of composite neonatal morbidity 21.4% vs 5.5% adjusted risk ratio aRR [95%CI] 4.0 [2.3-6.7], driven primarily by respiratory morbidity 20.3% vs 4.2%, aRR [95% CI] 4.8 [2.7-8.7]. Increasing polyhydramnios severity category was associated with a trend towards increased neonatal morbidity (mild 31/166 (18.7%), moderate 8/20 (40%), and severe polyhydramnios 2/2 (100%), p-value <0.01). IP is associated with increased risk of neonatal morbidity at term, driven primarily by respiratory morbidity. Pregnancies complicated by polyhydramnios should have neonatal respiratory support at the time of delivery.