In this research article, a descriptive study was applied during the period from January to August 2017 to evaluate maternal levels of leptin and make a comparison of serum leptin levels in typical pregnancies with those who are problematical by preeclampsia. A case study about (80) terms of primigravidas pregnant women who were attending AL Nomaan Teaching Hospital during the study period, 40 were known cases of preeclampsia and 40 were normotensive without another disease. Women have been monitored from admission time to delivery. Leptin levels have been determined in serum samples from the whole women. Mode of delivery and birth weight were identified as pregnancy outcome. The results revealed a statistically significant association between the disease and both decreased birth weight (small for gestational age) (p = 0.026) along with the delivery via cesarean section (p = 0.001). While neonatal birth weights have been considerably lower in women with preeclampsia in comparison to the control group (p < 0.001). Leptin levels have been greater in preeclamptic pregnant women as compared with normotensive, and high leptin in preeclampsia levels might be associated with increased adverse maternal and fetal outcome like low birth weight and raise the delivery hazard by cesarean section for different reasons.