Pre-eclampsia disrupts the normal relationship between serum leptin concentrations and adiposity in pregnant women

The adipocyte hormone, leptin, is secreted in proportion to adipose mass an d is implicated in the regulation of energy balance via its central actions on food intake and sympathetic nervous system activity. The placenta was a lso shown recently to be a possible source of leptin in pregnant women, rai sing the possibility that the normal relationship between leptin and adipos ity may be altered in pre-eclampsia. We therefore sought to assess the exte nt to which maternal second trimester serum leptin concentrations differed for women who would subsequently develop pre-eclampsia and those who would remain normotensive. This nested case-control study population comprised 38 women with pregnancy-induced hypertension and proteinuria (pre-eclampsia) and 192 normotensive women. Multiple least-squares regression procedures we re used to assess the independent relationship between leptin concentration s and risk of pre-eclampsia. Serum leptin concentrations, measured by radio immunoassay, were highly correlated with maternal pre-pregnancy and second trimester body mass index (r = 0.71 and r = 0.74 respectively; P < 0.001 fo r both) among normotensive women, and to a lesser extent among women who de veloped pre-eclampsia (r = 0.29 and r = 0.42; P = 0.09 and 0.02 respectivel y). Among women with a pre-pregnancy body mass index of less than or equal to 25 kg/m(2), pre-eclampsia cases compared with controls had higher mean s econd trimester leptin concentrations after adjustment for confounding fact ors. In contrast, preeclampsia cases had lower mean leptin concentrations t han controls for those women with a pre-pregnancy body mass index above 25 kg/m(2). Other factors in addition to the level of adiposity may therefore influence serum leptin concentrations in pre-eclamptic pregnant women. Our results suggest the possibility that leptin, like several other placentally derived substances (e.g. steroid hormones, eicosanoids and cytokines), may be involved in the pathogenesis of pre-eclampsia. Further work is needed t o confirm our findings and to assess the metabolic importance and determina nts of leptin concentrations in uncomplicated and preeclamptic pregnancies.