Standardization of amniotic fluid leptin levels and utility in maternal overweight and fetal undergrowth

Objective:leptin is an adipokine that regulates energy homeostasis. the objective of this study was to establish a gestational age-specific standard for amniotic fluid leptin (afl) levels and examine the relationship between afl, maternal overweight and fetal growth restriction.study design:amniotic fluid was obtained at mid-gestation from singleton gravidas, and leptin was quantified using enzyme-linked immunosorbent assay. amniotic fluid samples from 321 term pregnancies were analyzed. clinical data, including fetal ultrasound measurements and maternal and infant characteristics, were available for a subset of patients (n=45).results:the median interquartile range afl level was significantly higher at 14 weeks’ gestation (2133 pg ml−1 (1703 to 4347)) than after 33 weeks’ gestation (519 pg ml−1 (380 to 761), p trend<0.0001), an average difference of 102 pg ml−1 per week. afl levels were positively correlated with maternal pre-pregnancy body mass index (bmi) (r=0.36, p=0.03) adjusting for gestational age at measurement, but were not associated with fetal growth.conclusions:afl levels are higher at mid-gestation than at late gestation, and are associated with maternal pre-pregnancy bmi.