Maternal Obesity - Optimizing Weight Gain for Maternal and Infant Health—Less is More? (#367)
There are few areas in obstetric medicine as hotly contested as the optimal degree of gestational weight gain (or even weight loss) in overweight and obese pregnant women and the utility of interventions designed to limit gestational weight gain (GWG). Limiting GWG is one modifiable risk factor that may have significant potential to decrease the risk of childhood obesity and, according to WHO estimates, there will be 70 million obese children globally by 2025. Limiting GWG also decrease the risks of gestational diabetes (GDM), preeclampsia, cesarean delivery, postpartum weight retention, and long-term adverse metabolic outcomes in both mothers and infants. GWG less than the 2009 Institute of Medicine (IOM) guidelines in overweight and obese women has potential to further improve pregnancy outcomes and reduce large-for-gestational-age infants (LGA), an independent risk factor for childhood obesity. However, obese women are also at increased risk for having preterm and small-for- gestational age (SGA) infants, likely due to placental insufficiency, and there are concerns that targeting a lower GWG or even weight loss may further increase SGA in this population. The vast majority of studies investigating the effect of GWG on pregnancy outcomes in obese women have not controlled for maternal risk factors that may independently increase the risk of placental insufficiency, preterm birth, and SGA and broad recommendations on appropriate GWG for all obese women may not be feasible. Furthermore, most studies have analyzed the outcome of total GWG, rather than the timing of GWG, which may ignore that weight gain early versus late in pregnancy may modulate pregnancy outcomes by differentially adding to maternal fat deposition, worsening maternal insulin resistance, increasing the risk of GDM, or increasing fetal fat accretion. Tremendous efforts towards the execution of interventional trials to decrease excess GWG have met with some cynicism given they have only been modestly effective in improving pregnancy outcome. Critics who scrutinize the intensity and timing of the interventions challenge the value of conducting future trials. This talk examines the support for less GWG in overweight and obese women than recommended by the IOM, raises caveats that my limit the generalizability of these recommendations to all obese women, and queries whether interventional strategies designed to limit GWG and improve pregnancy outcomes are doomed by compliance issues, maternal-placental biology, or with appropriate modifications, have potential merit.