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Heavy Women Who Become Pregnant Face Greater Health Risks

Problems can include high blood pressure, fetal distress and neonatal death

THURSDAY, Feb. 5, 2004 (HealthDayNews) -- There are new reasons to control your weight both before and after you conceive -- particularly if you're heavy before you even try to have a baby.

Obesity promotes not only severe pregnancy complications in the mother, it also places the baby at high risk of health problems, including an increased chance of neonatal death.

That's the sobering news from a group of Swedish researchers who say that not only is it important to control weight gain during pregnancy, but to also get your level of body fat under control before you attempt to conceive.

"[We are hopeful] that knowing the problems concerning pregnancy and delivery associated with obesity could possibly motivate young women to prevent excessive weight gain," says study author Dr. Marie Cendergren. She is an obstetrician in the division of obstetrics and gynecology at Linkoping University, where the research was conducted.

The findings appear in the February issue of Obstetrics and Gynecology.

Although Cendergren believes that reaching as close to a "normal" weight as possible before conception is the best way to avoid problems, she acknowledges this would be difficult for most women suffering from obesity.

However she adds that "a BMI below 30 significantly reduces risks," and she encourages women to aim for that goal. A BMI, or body mass index, is an indication of the level of body fat. A "normal" BMI ranges from 19 to 26, depending on height, Cendergren says.

Among the pregnancy problems cited by the study was an increased risk of preeclampsia, a potentially fatal form of maternal high blood pressure. Other problems include increased likelihood of Caesarean-section delivery; greater risk of shoulder dystocia (damage to the baby's arm and shoulder during delivery); fetal distress; stillbirth; and death of the child shortly after birth.

Although losing weight before pregnancy would help reduce the risk of all these problems, Cendergren suggests that for even greater insurance, all obese women should be under the care of a high-risk pregnancy expert.

"We must look upon these pregnancies and deliveries as high-risk pregnancies -- particularly the doctors dealing with them," Cendergren says.

New York University obstetrician Dr. Michael Silverstein says the study underscores the importance of watching your weight both before and after pregnancy. But, he adds, this is information most physicians have known for a long time.

"Whether the weight gain occurs before pregnancy or after conception takes place, if you are very overweight it is going to cause a litany of problems affecting both the mother and the baby," Silverstein says. Even something as routine as a pregnancy ultrasound -- to check for fetal growth and development -- can be difficult or impossible to accurately read when the mother is very overweight.

"I'm not certain if the excess weight is causing these birthing complications, or if the weight is keeping us from properly diagnosing certain conditions that we might otherwise normally see -- particularly those involving fetal distress," Silverstein says.

While he agrees that some obese women do require the care of a high-risk pregnancy expert, he also believes every pregnancy should be viewed in an individual light.

"A lot depends on the overall health of the mother. A very overweight woman who is in good physical condition may be of less concern than a woman who is moderately overweight but is in poor physical condition or is carrying more than one baby," he says.

The Swedish study looked at nearly 3,500 pregnancies in morbidly obese women -- defined as a body mass index over 40. An additional 12,698 women with a BMI between 35.1 and 40 were also part of the study. All were compared to pregnant women with a normal BMI, falling between 19.8 and 26.

The result: Women with a BMI greater than 40 were at significantly heightened risk for preeclampsia; stillbirth; Caesarean delivery; instrument delivery, (such as forceps); shoulder dystocia; meconium aspiration (a newborn breathing-related procedure), fetal distress; early neonatal death; and large-for-gestational-age -- a problem that can lead to other birth complications.

Although women with a BMI between 35.1 and 40 also were subjected to the same risks, the incidence was notably lower. Indeed, researchers say the lower a woman's BMI, even by just a few points, the lower her risk of problems.

According to Cendergren, the risk of gaining excessive amounts of weight during pregnancy is as detrimental as being very overweight going into the pregnancy.

More information

To learn more about obesity and pregnancy, visit The March of Dimes. Or visit the National Heart, Lung, and Blood Institute for the very latest guidelines on controlling obesity.

SOURCES: Marie Cendergren, M.D., division of obstetrics and gynecology, department of Molecular and Clinical Medicine, Family of Health Sciences, Linkoping University, Linkoping, Sweden; Michael Silverstein, M.D., assistant professor, obstetrics and gynecology, New York University School of Medicine, New York City; February 2004 Obstetrics and Gynecology
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