Purpose: to study in primigravid adolescents the behavior of serum leptin levels during the evolution of normal pregnancy, comparing the results with those obtained from preeclamptics. Methods: prospective, longitudinal study conducted in 15 normotensive pregnant adolescents and 5 preeclamptic adolescents. Serum leptin levels (ng/mL) were determined by radioimmunoassay. Blood pressure was measured by the oscilometric method by using DINAMAP 1846. Patients were evaluated in two different gestational periods: between the 21st and 30th week and between the 31st and 40th week. The ratio leptin/body mass index (BMI) was used to correct changes observed in BMI throughout gestation. Preeclamptic pregnant patients were diagnosed when the blood pressure was > or = 140/90 mmHg, proteinuria >300 mg/24 h and when arteriolar spasm was present in the optic fundi. Results: there was a trend towards an elevation of serum leptin at the end of pregnancy in both groups although more pronounced in preeclamptic patients. In pregnant normotensive patients serum leptin increased from 11.9±1.20 (21stto 30th week) to 13.9±2.23 ng/mL (31st to 40th week), and in preeclamptic from 11.9±1.20 to 17.6±4.565 ng/mL. In preeclamptic patients the BMI increased significantly in the period from the 21st to 30th week when compared to the period between the 31st and 40thweek: 21.5±0.8 vs 27.4±1.7 kg/m², p<0.05.In normotensive these values were maintained stable: 24.9±1.5 vs 25.1±1.00 kg/m². At the end of gestation the ratio leptin/BMI was significantly higher in preeclamptics: 0.56±0.06 (21stto 30thweek) vs 0.70±0.15, p<0.05. The values of the ratio leptin/BMI in normotensive pregnants varied from 0.44±0.02 between the 21st and 30th week to 0.41±0.04 between the 31st to 40thweek. In normal pregnants there was a direct and significant correlation between the levels of leptin and BMI in both periods of pregnancy: r = 0.7, p<0.004 (31st to 40th ) vs r = 0.94, p<0.0001 (31st to 40th week). These correlations were lost in preeclamptic patients in both gestational periods. Conclusion: the higher concentrations of leptin and leptin/BMI ratio observed when preeclamptics were compared with normotensive patients, in both gestational periods, suggest a leptin resistance pattern in preeclampsia.
Complications of pregnancy; Hypertension; Leptin; Body mass index
