Trying to get pregnant? Make sure you know the bottom line on baby-making—what you don't understand can affect your bub-to-be's health.
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In increasing number of American women who want to get pregnant soon might want to reconsider their timing: They’re overweight. A study that looked at 53,000 pregnant women’s weight at their first prenatal visit found that the average had increased by 20 percent from 1980 to 1999. That’s bad news for them and their babies.
“Doctors have long known that very obese women risk pregnancy complications, but new research indicates that even women who are not hugely overweight have elevated risks,” says Hugh M. Ehrenberg, M.D., of Case Western Reserve School of Medicine in Cleveland, the lead author of a recent study on obesity and pregnancy published in the American Journal of Obstetrics and Gynecology. The list of potential complications is formidable: hypertension, preeclampsia and eclampsia, gestational diabetes (which can lead to overly large babies), Cesarean delivery and postoperative complications.
There’s more: A new Centers for Disease Control and Prevention study confirmed that a woman who is overweight before becoming pregnant is two to three times more likely to have a baby with heart abnormalities, spina bifida or other birth defects. Another new study links excess weight and obesity to lower levels of the “lactation hormone” prolactin after childbirth, which may explain why overweight women tend to stop nursing earlier than average-weight women. Finally, weight gained during pregnancy can be cumulative and difficult to lose (see “The Road to Obesity” on pg. 64).
To prevent such problems, a woman should, if possible, be at or close to her ideal weight when she becomes pregnant. Sometimes losing just 5 to 10 percent before getting pregnant is enough to decrease her risk factors. But since not every pregnancy is planned, many overweight women want to know whether—and how—they can safely deal with their weight while pregnant. The thinking on this issue is changing.
Revising the weight-gain rules> “We used to tell all women to gain 25 to 35 pounds during pregnancy, but now we suggest that an overweight or obese woman gain only 15 to 25 pounds,” says Paula Bernstein, M.D., an OB-GYN in Los Angeles and a co-author of Carrying a Little Extra: A Guide to Healthy Pregnancy for the Plus-Size Woman (Penguin Putnam, 2003). That’s because an overweight woman already has a greater store of the nutrients her developing baby needs.
A body mass index (or BMI, a formula that relates weight to height) of 25 to 29.9 is considered overweight, while a BMI greater than 30 is the current standard for obesity. “Even a woman with a BMI of 25 begins to be at risk for pregnancy complications,” Bernstein says.
Though doctors currently advise against losing weight during pregnancy, Ehrenberg is investigating whether doing so might benefit a very heavy woman’s health without risking her baby’s. One concern is that ketosis—the incomplete metabolism of fatty acids that occurs when carbohydrates are severely limited and weight loss occurs rapidly, as is the case with high-protein diets—may harm a fetus. But a balanced, calorie-restricted diet can result in weight loss without causing ketosis.
“Until now, the research regarding weight loss during pregnancy has been done on women who are already at an ideal weight,” Ehrenberg says. “But as a significant number of women now are overweight when they become pregnant, we need to establish whether they can lose weight through diet and exercise without harming their baby.”