Serum leptin measured in early pregnancy is higher in women with preeclampsia compared with normotensive pregnant women

Leptin, an adipocyte-derived hormone, plays an important role in reproduction and angiogenesis. Studies examining leptin in preeclampsia are inconsistent, possibly because of small sample sizes and variability in sampling and outcome. We conducted a nested casecontrol study to examine associations between serum leptin (measured: 926 weeks gestation) and preeclampsia among 430 primiparous preeclamptic women and 316 primiparous normotensive controls from the Danish National Birth Cohort. Median (interquartile range) leptin concentrations were calculated. Associations between leptin and preeclampsia (blood pressure 140/90 mm Hg), term preeclampsia (preeclampsia and delivery 37 weeks gestation), or preterm preeclampsia (preeclampsia and delivery 37 weeks gestation) were examined using generalized linear models adjusting for body mass index, gestational age at blood draw, maternal age, smoking, and socio-occupational status. As leptin is increased in obese women and the risk of preeclampsia increases with body mass index, we used the Sobel test to examine whether leptin is a mediator of this relationship. After adjustments, leptin concentrations were significantly higher in women with preeclampsia (30.5 [24.6]; <italic>P</italic>=0.0117) and term preeclampsia (30.4 [24.9]; <italic>P</italic>=0.0228) compared with controls (20.9 [28.3]). There was no significant difference between preterm preeclampsia (30.6 [23.4]; <italic>P</italic>=0.2210) and controls. Leptin is a possible mediator of the association between body mass index and preeclampsia (<italic>P</italic>=0.0276). Leptin concentrations are higher in women with preeclampsia compared with normotensive controls and may mediate some of the relationship between body mass index and preeclampsia.