Obesity is well known to be a contributory risk factor for several disease states, including diabetes mellitus. Further, obese women are more prone to have babies born with congenital abnormalities. Paucity of data on maternal-fetal disposition of essential trace elements in obese pregnancies prompted us to undertake this study. Maternal venous and umbilical arterial and venous samples were collected from obese patients (body mass index >30) and control pregnant women (body mass index <25) at time of spontaneous delivery or cesarean sections and concentrations of essential trace elements such as Cu, Fe, Mo, Se, and Zn determined in various samples by atomic absorption spectrophotometry. Activities of antioxidant enzymes, superoxide dismutase, glutathione peroxidase, and total antioxidant activity in maternal and umbilical blood were assessed using appropriate reagent kits. Maternal-fetal disposition and exchange parameters of elements studied were assessed using established criteria. Concentrations of Cu, Fe, Mo, Se, and Zn in the serum of control pregnant women at time of delivery averaged 2232.6, 2398.1, 10.9, 108.9, and 661.9 microg/L respectively, whereas in the obese group, the values of the above elements averaged 2150.3, 2446.8, 12.6, 96.8, and 838.9 microg/L respectively. Umbilical vein/maternal vein ratios of Cu, Fe, Mo, Se, and Zn in the control group averaged 0.29, 1.93, 1.06, 0.76, and 1.12, respectively, whereas in the obese group, their fetal-maternal ratios averaged 0.32, 2.23, 1.06, 0.78, and 1.53, respectively. The Cu : Zn ratio in the maternal vein of the obese group (3.60 +/- 0.20) was significantly lower (Student's t-test; p < 0.05) than that of the controls (2.50 +/- 0.19); however, Cu : Fe ratio (1.04 +/- 0.08 vs 1.02 +/- 0.09) was not significantly different (Student's t-test; p > 0.05) in the two groups. Varying differences were noted in the case of antioxidant enzyme activities between the control and study groups. We conclude that obesity is associated with alterations in maternal-fetal disposition of some essential trace elements and antioxidant enzyme status and that these alterations could pose a potential health risk for the mother as well as the fetus.