Maternal obesity-related placental dysfunction: From peri-conception to late gestation

Obesity is a global epidemic with alarmingly high prevalence rates worldwide. The increasing incidence of obesity among reproductive age women, which progresses to obesity in pregnancy is of particular concern. A successful pregnancy is dependent on the balanced interaction between maternal cardiometabolic function, genetic predisposition, and optimal placental development. Maternal obesity, both pre-pregnancy and gestational, has been associated with adverse outcomes including poor fetal development, stillbirth, preterm birth, and metabolic complications later in life. To gain a more comprehensive understanding of the mechanistic interplay of key mediators of obesity-associated placental dysfunction and adverse pregnancy outcomes, we conducted a review of 24 studies that investigated placental dysfunction and maternal obesity retrieved from MEDLINE, LILACS and EMBASE. The findings demonstrate that maternal obesity is a well-established risk factor for poor placental function. Pre-pregnancy obesity alters the placental transcriptome. Maternal obesity during gestation induces changes in placental morphology, dysregulated placental metabolism, inflammation and oxidative state, as well as endothelial dysfunction. There is also clear evidence that maternal obesity is associated with altered placental angiogenesis/vascularisation which increases the risk of early-onset preeclampsia. Studies show a link between maternal obesity and increased placental vascular disorders, placental weight, placental volume and birth weight. These obesity-related placental disorders are often associated with insulin resistance and gestational diabetes mellitus.