Excessive gestational weight gain (GWG) is common and on the rise. While mean weight gains tend to be lower among women entering pregnancy at higher pre-pregnancy weights, weight gain ranges associated with optimal outcomes are also lower for heavier women [1,2]. Thus overweight and obese women are substantially more likely to gain more weight than recommended (“excessive weight gain”), compared with women who were normal weight or underweight entering pregnancy .
As summarized in Chapter 4, a large number of observational studies have demonstrated increased risks for adverse short- and long-term pregnancy outcomes associated with excessive GWG [1,3]. For the mother, these adverse outcomes include gestational glucose intolerance, cesarean or complicated vaginal delivery, failure to initiate or maintain breastfeeding, and postpartum weight retention [3,4]. For the child, they include large for gestational age, birth trauma, and infant mortality, as well as increased risk for later obesity [2,3,5–7]. Observational data further suggest that risks for many adverse outcomes associated with greater GWG are similar or greater among obese women than among women of normal pre-pregnancy weight. In studies of birth outcomes among obese women, higher gains appear to raise the risk of large for gestational age more strongly than they reduce the risk of small for gestational age birth [5,8–13]. These findings suggest that reducing GWG among obese women may have beneficial effects without causing undue risk.