Pregnancy and placental outcomes according to maternal BMI in women with preeclampsia: a retrospective cohort study

Purpose: Obesity and preeclampsia share similar patho-mechanisms and can both affect placental pathology. We aimed to investigate pregnancy outcomes in correlation with placental pathology among pregnancies complicated by preeclampsia in three different maternal body mass index (BMI, kg/m²) groups. Methods: In this retrospective cohort study, medical and pathological records of patients with preeclampsia and a singleton pregnancy delivered between 2008 and 2021 at a single tertiary medical center were reviewed. Study population was divided into three BMI groups: BMI < 22.6 kg/m² (low BMI group), 22.7 ≤ BMI ≤ 28.0 kg/m² (middle-range BMI group), and BMI > 28.0 kg/m² (high BMI group). Data regarding maternal characteristics, neonatal outcomes, and placental histopathological lesions were compared. Results: The study groups included a total of 295 patients diagnosed with preeclampsia—98, 99, and 98 in the low, middle-range, and high BMI groups respectively. Neonatal birth weight was significantly decreased in the low maternal BMI group compared to both middle and high BMI groups (p = 0.04) with a similar trend seen in placental weight (p = 0.03). Villous changes related to maternal malperfusion were more prevalent in the low and high BMI groups compared to middle-range BMI group (p < 0.01) and composite maternal vascular malperfusion lesions were also more prevalent in the groups of BMI extremities compared to the middle-range BMI group (p < 0.01). Conclusion: Maternal BMI might influence neonatal outcomes and placental pathology in pregnancies complicated by preeclampsia. Both extremes of BMI were associated with higher rates of placental maternal vascular malperfusion. Balanced BMI in women at risk for preeclampsia may reduce the incidence of placental lesions.