The severity of polyhydramnios, estimated fetal weight and preterm delivery are independent risk factors for the presence of congenital malformations

Objective: To evaluate maternal and fetal factors associated with congenita l malformations in patients with polyhydramnios. Study Design: The study gr oup consisted of 275 singleton pregnancies with an amniotic fluid index (AF I) >25.0 cm. An equal number of controls were matched for maternal age, gra vidity, parity and gestational age. The proportion of cases and controls wi th malformations was compared. Polyhydramnios cases were categorized into t hree groups by severity: mild (AFI 25-30 cm), moderate (AFI: 30.1-35.0 cm) and severe (AFI >35.1 cm). Among cases, logistic regression ana lysis was u tilized to estimate the risk for fetal congenital malformations in relation to severity of polyhydramnios, estimated fetal weight, maternal dia betic status and gestational age at delivery. Results: Congenital malformations w ere detected in 40 of 275 cases (14.5%) with polyhydramnios and in 9 cases (3.3%) of the control group (p < 0.01). The relative risks of congenital ma lformations increased with the severity of polyhydramnios: 3.2 (95% CI 1.5- 6.8), 5.7 (95% CI 2.4-13.3) and 13.1 (95% CI 5.8-29.5) for mild, moderate a nd severe polyhydramnios, respectively Congenital malformations among polyh ydramnios cases were present in 54.5% of small-for-gestational age fetuses, in contrast to 12.7% for average-for-gestational age fetuses and 10.8% for large-forgestational age fetuses (p < 0.001). Maternal dia betic status di d not significantly affect the fetal anomaly rate once polyhydramnios was d etected. Premature newborns in the polyhydramnios group had a higher malfor mation rate (24%) than did term newborns (11.3%) (p < 0.02). In the study g roup, multiple logistic analysis confirmed the significance of severe polyh ydramnios, small-for-gestational age status and preterm delivery as indepen dent contributors to the malformation risk. Conclusions: Polyhydramnios (AF I >35 cm), small-for-gestational age fetus and preterm delivery are indepen dent risk factors for congenital malformations.