May 18, 2012 — -- At a time when women are "eating for two," dieting can safely lower the health risks of obesity during pregnancy, according to a new study.
British researchers reviewed data from 44 trials involving 7,278 women to determine the safety and effectiveness of weight management programs during pregnancy. Not only did the moms-to-be gain less weight, they also lowered their risk of dangerous complications.
"Dietary interventions were most effective in reducing complications such as preeclampsia, gestational diabetes, gestational hypertension, and preterm delivery," the researchers wrote in their report, published Thursday in BMJ.
Babies benefitted, too, as they were less likely to get stuck in the birth canal despite no difference in birth weight.
"There is no evidence that the interventions evaluated in our review or recommended in current clinical practice are associated with adverse maternal or fetal outcomes," the authors wrote.
Nearly half of U.S. women who are of child-bearing age are obese, according to a 2009 study in the Maternal and Child Health Journal.
The growing problem prompted "Obese & Expecting," a TLC documentary that followed four obese women through complicated pregnancies and painful deliveries. A scene from the special shows doctors struggling to give one woman an epidural through the fat in her back.
"We spent 45 minutes attempting to put the spinal in," said Dr. Charles Hux, a New Jersey OB/GYN featured in the documentary. "With so many layers of fat, it's difficult to be certain that the needle went into the exact space it should go in."
After several tries, the team gave up, deciding instead to give the woman a general anesthetic and a C-section.
"Going to sleep carries significant risks, even for a slim pregnant woman," said Dr. Marjorie Greenfield, division chief of general obstetrics and gynecology at University Hospitals Case Medical Center in Cleveland. "And the risk goes up significantly in a woman who's overweight."
Obesity also compromises prenatal care, according to Greenfield.
"It's harder to provide excellent care to someone who's obese because a lot of things we do are not as accurate," said Greenfield, explaining how ultrasounds and other tests to gauge the baby's growth can be skewed by the mother's fat. "It's also harder to feel the position of the baby."
The extra fat, and the fact that obesity can cause irregular periods, also means women might not immediately realize they're pregnant.
"If you don't know you're pregnant, you might not avoid things that are toxic, like alcohol, smoking and certain medications," said Greenfield, adding that prenatal vitamins are also important. "And a lot of what we do in prenatal care depends on knowing exactly how far along a woman is. If you don't have a sense of gestational age, it's harder to provide the right care."
Weight gain during pregnancy is normal. But obese women should gain no more than 15 pounds, according to guidelines. That's roughly half the amount recommended for women of normal weight.
"For someone with bad eating habits, that's going to be really hard," said Greenfield, describing how pregnancy cravings and the "eating for two" mentality can conspire to pack on the pounds.
Women who dieted during pregnancy gained roughly three pounds less than women who did not, according to the BMJ study. And that's good, said Greenfield, because it's less weight to lose later.
"Women who put on a lot of weight during pregnancy often can't get it off again," she said. "It's definitely contributing to the obesity epidemic."
Rising rates of obesity among moms-to-be has forced hospitals to adapt, adding delivery tables that can be made wider and hold up to 600 pounds.
"The old tables only went up to 450 pounds," Greenfield said. "That's just not realistic anymore."