Idiopathic polyhydramnios at term and pregnancy outcomes: a multicenter observational study

Aim: To assess pregnancy outcomes in pregnancies with idiopathic polyhydramnios at term.Methods: We conducted a retrospective cohort study of 106 225 term pregnancies from 37 hospitals in China. Maternal and fetal outcomes in pregnancies with idiopathic polyhydramnios were compared with pregnancies with normal amniotic fluid. The primary outcome was intra-uterine fetal death (IUFD).Results: In all, 307 out of 106225 (0.3%) had idiopathic polyhydramnios at term, 276 of which were mild and 31 of which were moderate-severe. Compared to term pregnancies with normal amniotic fluid, pregnancies idiopathic polyhydramnios was associated with over 24-fold higher risk for IUFD (adjusted odds ratio [aOR] 24.4, 95% confidence interval (CI) 7.3-82.0), macrosomia (aOR 2.8, 95%CI 2.0-3.8), malpresentation (aOR 2.5, 95%CI 1.7-3.7), cesarean delivery (aOR 2.5, 95%CI 1.7-3.7) and low APGAR scores at 5min (aOR 4.3, 95%CI 2.4-7.8), which increased with severity of idiopathic polyhydramnios.Conclusion: Term pregnancies with idiopathic polyhydramnios, especially moderate-severe ones are at a significantly increased rate for adverse pregnancy outcome. Increased antepartum surveillance of fetal well-being and timed delivery are warranted.