Impact of obesity on uteroplacental immunology and placental pathology

Obesity is a growing problem. Currently 1 in 3 reproductive-age women is obese. This is significant because obesity is associated with an increased risk of gestational diabetesmellitus (GDM), pretermbirth, fetal growth abnormalities, preeclampsia, and stillbirth. Obesity alone increases the risk of stillbirth by threefold, whereas GDM increases this risk to approximately 10-fold. How obesity and GDM affect placental and fetal growth are beginning to be understood, but the underlying pathophysiology leading to bad pregnancy outcomes is essentially unknown. This review will discuss the effects of obesity and GDM on fetoplacental growth, the histopathologic features seen in these placentas, how obesity may affect uterine spiral artery remodeling, and why this leads to placental insufficiency. New insights suggest that abnormal regulation of maternal T cells and uterine natural killer cells may be important in the disease process, but much more research is needed.