Interrelationships of maternal serum leptin, body mass index and gestational age.

BACKGROUND The aim of this study was to evaluate the interrelationships between maternal serum leptin level and body mass index (BMI) at different gestational ages or during the whole pregnancy. METHODS A total of 374 blood samples were obtained from 114 pregnant women when they visited the prenatal clinic for registration, Down syndrome screening test, 50 g oral glucose challenge test, hepatitis B markers test, and near or at the time of delivery. Serum leptin levels were measured by immunoradiometric assay. Linear regression analysis, 1-way ANOVA and post hoc tests were used to analyze the data. RESULTS Throughout the course of pregnancy, maternal serum leptin concentration was significantly correlated with gestational age (p = 0.001, r = 0.179). A good correlation was also found between gestational age and maternal serum leptin level in the second trimester (p = 0.021, r = 0.158). A significant decline in maternal serum leptin was found in the third trimester (p = 0.011, r = 0.237). There were good correlations between maternal leptin and BMI in all 3 trimesters (p = 0.002 in the first trimester, p < 0.001 in the second trimester, p = 0.007 in the third trimester) and through the whole pregnancy (p < 0.001). Maternal BMI was related to gestational age in the second trimester (p < 0.001) and the whole pregnancy (p < 0.001), but not in the first (p = 0.404) and third trimesters (p = 0.053). CONCLUSION Maternal serum leptin concentration was significantly related to gestational age (except in the first trimester) and BMI in the 3 trimesters and throughout pregnancy. Serum leptin concentration peaked during the early third trimester and declined significantly thereafter. Maternal BMI was related to gestational age in the second trimester and the whole pregnancy.