Sexual dimorphism in the levels of amniotic fluid leptin in pregnancies at 16 weeks of gestation: Relation to fetal growth

ObjectiveTo investigate whether in the first half of pregnancy levels of leptin in amniotic fluid are sexually dimorphic, and are related to fetal growth.Study designSamples of amniotic fluid were collected during amniocentesis from 211 pregnancies with a single fetus with a normal karyotype (107 from male fetuses). Fetal growth was evaluated at 16 and 32 weeks of gestation, by sonography, and in a subset of 137 women at delivery.ResultsAmniotic fluid leptin was significantly lower in male than female fetuses (7.91 ± 0.36 ng/ml versus 10.45 ± 0.38 ng/ml; p = 0.0001). In females, levels of leptin were inversely related to BPD measured at 16 weeks (r = −0.241; p = 0.013) to biparietal diameter (BPD) (r = −0.281; p = 0.0076) and abdominal circumference (r = 0.268; p = 0.0107) measured at 32 weeks of gestation and to neonatal weight (r = −0.236; p = 0.051), neonatal weight/height (r = −0.271; p = 0.026) or neonatal Kaup index (r = 0.255; p = 0.045). Leptin was not related to any fetal parameter in males.ConclusionsLevels of leptin in amniotic fluid at 16 weeks of gestation are sexually dimorphic and are inversely related to fetal growth, particularly of females.