New guidelines recently reduced the recommended weight gain for obese women during pregnancy to 11-15 pounds. Now, one trial wants them to reduce it to zero.
That would be the four-year Healthy Moms study, which wants obese participants to gain between zero and 3% of their body weight, or 5 pounds for a 170-pound woman. The New York Times coverage of the study, by Roni Caryn Rabin, doesn't explicitly state what women are supposed to do about the weight of the fetus and placenta, but the implication is that they should actually be losing some of their own weight to make room for them. Rabin says experts think women only need an extra 300 or 400 calories a day to have a healthy pregnancy, and that many obese women deliver healthy babies with no weight gain at all. The researchers in charge of the study hope to show that zero weight gain makes for easier delivery and decreases the baby's chance of obesity later on. But the advocates behind reducing pregnancy weight gain may also hope to set obese women on a path to weight loss. Says Prof. Kathleen M. Rasmussen, who worked on this year's earlier 11-15 pound guideline, "Pregnancy is what we call a teachable moment, a time when women are willing to make positive behavioral changes, because it's important for their own health and their babies' health."
But there's some evidence that pregnancy isn't the time to make big behavioral changes, at least not if they involve weight loss. If women burn fat during pregnancy, they may increase their blood levels of ketones, which in turn may lower a baby's IQ. The Healthy Moms study apparently doesn't plan to track the mental development of babies and children after birth, but some argue that it should. Then there's the risk to mom and baby of unhealthy weight loss. As Kate Harding pointed out in October, "the health care providers pregnant women visit most often aren't necessarily trained to recognize and address body image issues and eating disorders - but they are trained to track expectant mothers' weight and instruct them to keep it within a certain range. For women who struggle with disordered eating and body dissatisfaction, that can be problematic." And eating disorders can cause problems for the developing fetus as well as the mother.