Pregnancy weight gain: still controversial.

During the 20th century, recommendations for maternal weight gain in pregnancy were controversial, ranging from rigid restriction to encouragement of ample gain. In 1990, the Institute of Medicine (IOM) recommended weight-gain ranges with the primary goal of improving infant birth weight. These guidelines were widely adopted but not universally accepted. Critics have argued that the IOM's recommendations are unlikely to improve perinatal outcomes and may actually increase the risk of negative consequences to both infants and mothers. We systematically reviewed studies that examined fetal and maternal outcomes according to the IOM's weight-gain recommendations in women with a normal prepregnancy weight. These studies showed that pregnancy weight gain within the IOM's recommended ranges is associated with the best outcome for both mothers and infants. However, weight gain in most pregnant women is not within the IOM's ranges. All of the studies reviewed were observational and there is a compelling need to conduct experimental studies to examine interventional strategies to improve maternal weight gain with the objective of optimizing health outcomes.