Severity of polyhydramnios does not affect the prevalence of large-for-gestational-age newborn infants.

The purpose of this study was to evaluate the relationship between the severity of polyhydramnios with or without maternal diabetes and the prevalence of large-for-gestational-age newborn infants. A case control design was used. The study group consisted of 275 singleton pregnancies with an amniotic fluid index > or = 25.0 cm. An equal number of controls was matched for maternal age, gravidity, parity, and gestational age. Polyhydramnios was categorized into three groups by severity: mild (amniotic fluid index 25 to 30 cm.); moderate (amniotic fluid index, 30.1 to 35.0 cm); and severe (amniotic fluid index > or = 35.1 cm). Among our study group, 72.7%, 19.7%, and 7.6% of cases had mild, moderate, and severe polyhydramnios, respectively. Patients with polyhydramnios had a significantly higher prevalence of large-for-gestational-age neonates (27%) than did controls (10%) (P < 0.001). No correlation was seen between the severity of polyhydramnios and neonatal delivery weight. The prevalence of gestational and class > or = B diabetes mellitus was significantly higher among patients with polyhydramnios (17.7%) than among controls (7%) (P < 0.003). Once polyhydramnios was diagnosed sonographically, however, maternal diabetic status did not affect the prevalence of large-for-gestational-age newborn infants. We conclude that the prevalence of large-for-gestational-age neonates is 2.7 times greater when polyhydramnios is present than when the amniotic fluid volume is normal. Neither the severity of polyhydramnios nor the presence of maternal diabetes mellitus strengthens the relationship between polyhydramnios and large-for-gestational-age newborn infants.