The Effect of Maternal Obesity on Pregnancy Outcome in Correlation with Placental Pathology

Objectives: To investigate the effect of maternal obesity on pregnancy outcome and placental histopathology. Study Design: Pregnancy outcome and placental histology from term pregnancies were reviewed. Women were divided according to their prepregnancy body mass index (BMI, kg/m²) as normal weight (18-24.9) and obese (≥30). Pregnancy outcome and placental histology were compared between obese and normal weight women with complicated pregnancies, and with uncomplicated pregnancies, matched by mode of delivery. Placental lesions were classified as lesions of maternal or fetal vascular supply and maternal (MIR) and fetal (FIR) inflammatory responses. Results: Of the 1047 complicated pregnancies analyzed, 615 were with normal weight (BMI 21.7 ± 1.8) and 221 were obese (BMI 35.2 ± 4.3). Obesity was associated with higher rates of diabetes and hypertensive disorders (P =.001 for both), birth weight >90th, P <.001, and cesarean delivery, P <.001. Placental weight was higher in obese than in normal weight women, P <.001. No difference was observed in the rate of placental lesions related to maternal or fetal vascular supply and MIR or FIR between the groups. However, higher rate of maternal placental vascular lesions (46.8% vs 28.2%, P =.012) was observed in uncomplicated obese women (n = 62) as compared with healthy normal weight (n = 124) uncomplicated controls. Conclusion: Pregnancy outcome is worse without different placental component in obese versus normal weight women, with complicated pregnancies. In uncomplicated pregnancies, more maternal placental vascular supply lesions exist in obese versus normal weight women, suggesting background placental compromise.