Plasma leptin levels predict weight retention after pregnancy

Background: Leptin, a recently discovered polypeptide hormone is released from the adipocyte and acts on the hypothalamus, the site of appetite regulation in the brain. How the body regulates gestational weight gain and why some women gain excessive weight is not known. We hypothesized that this excess weight gain results from a reduced sensitivity to the action of leptin together with compensatory increases in its concentration during pregnancy. Methods: We examined the relationship between plasma leptin levels and the subsequent changes in weight from entry to care (at 17 weeks' gestation, baseline) until 6 months postpartum in a group of 103 pregnant women. Findings: The leptin concentration at baseline significantly predicted weight gain during pregnancy, and retained weight in the postpartum period. A one unit increase in the plasma leptin concentration at baseline corresponded to an increase in the rate of weight gain of 0.0045 ± 0.002 kg/week for a net increase of 0.18 ±.06 kg body weight by delivery (p< 0.01 for each). Interpretation: An impaired response to leptin is a risk factor for and a predictor of weight gain during and retention after pregnancy.