Cause of stillbirth and pathophysiological pathways in mothers with overweight and obesity

Abstract Purpose Obesity is independently associated with stillbirth, especially in early gestation and late-term gestation. Underlying pathophysiological mechanism causing fetal death is yet not clear. The purpose of this study was to determine the association between maternal body mass index and stillbirth and its importance in potential pathophysiological mechanisms of fetal death. Methods In a multicenter prospective cohort study from 2002 to 2008, 1.025 women with a fetal death > 20 weeks of gestation were studied. An extensive diagnostic workup was performed including maternal blood tests, coagulation tests, autopsy and placental examination. Cause of death was classified by a multidisciplinary panel. Odds ratios for each outcome stratified by gestational age were estimated for different maternal BMI classes (underweight BMI  30.0) compared with normal weight women (BMI 18.5–24.9) by using logistic regression and cause of death was studied. Results We analysed 793 women. Obese women significantly more often had pre-existing hypertension, pregnancy induced hypertension or gestational diabetes. Early fetal death (< 37 weeks) in obese women is more often caused by placental bed pathology (OR 4.10, 95% CI 1.79–9.40, P 0.001), and term fetal death by developmental placental pathology (OR 1.93, 95% CI 1.01–3.71, P 0.05). Conclusion In obese women there are at least 2 distinct underlying pathophysiological pathways causing fetal death. The underlying mechanisms of these pathways are uncertain and should be investigated in future.