Serum leptin and lactational amenorrhea in well-nourished and undernourished lactating women

To ascertain the possible role of leptin in the resumption of postpartum menstruation in lactating women with differing nutritional statuses. Analysis of data and blood samples collected during a previous prospective study. Healthy volunteers in an academic research environment. Undernourished (body mass index [BMI]≤19 kg/m 2) and well-nourished (BMI≥26 kg/m 2) lactating women who resumed regular menstruation before 24 weeks and at or after 24 weeks postpartum. Venous blood samples at four-weekly intervals and other clinical data collected until resumption of regular menstruation. Serum leptin concentrations. Leptin concentrations were significantly higher in the well-nourished than in the undernourished women, irrespective of the time of resumption of menstruation. Time of resumption of menstruation did not significantly affect leptin levels within well-nourished and undernourished groups. Leptin significantly correlated with BMI (r = 0.78). The BMI (r = −0.53), but not leptin, was significantly and negatively correlated with the duration of lactational amenorrhea. Leptin is unlikely to be a major determinant of early resumption of regular menstruation in well-nourished women.