The rate of obesity in adult women in the United States is 35.3 percent, and many of those women live in Alabama, the second most obese state in the nation. Obesity is responsible for a number of health problems, including pregnancy complications.
Joseph R. Biggio, MD, Director of the Division of Maternal Fetal Medicine at UAB, says obese mothers are at increased risk for a number of complications during pregnancy, including miscarriage, hypertension, preeclampsia, gestational diabetes, and fetal growth abnormalities. "These patients also are two to three times more likely to need a Caesarean section and to have postpartum hemorrhage," he says. "A C-section also has increased risks for wound breakdown and infection and venous thrombosis."
Babies of obese mothers are at increased risk for stillbirth and certain fetal anomalies, especially those involving the cardiac and central nervous systems, Biggio says. "If the mother also has gestational diabetes, the baby will more likely be large for gestational age and have an increased birth weight." Mothers and their babies may also have long-term consequences from an obese pregnancy. "We know that an obese woman is likely to retain weight she gained during pregnancy. This becomes an ongoing cycle with subsequent pregnancies and ultimately further increases her risk for diabetes and other health problems," Biggio says. Women who lose as little as 10 percent of their weight between pregnancies lower their risks for pregnancy complications by as much as 50 percent.
Obese mothers generally give birth to larger babies, and Biggio says birth weight and neonatal adiposity are tremendous predictors of obesity in the child, even as early as 2 years of age. "These children are two times more likely to be obese and by as early as 7 or 8 years old will already s how signs of high blood pressure," he says. "In adolescence, many of these children already are obese with lipid abnormalities and hypertension indicative of metabolic syndrome."
While research indicates birth defects can result from obesity in the mother, new studies show that diabetes may partially account for these risks. "Type 2 diabetes, which is closely related to obesity, has been linked to a heightened risk of birth defects in a number of studies," Biggio says.
A new study followed almost 42,000 women who gave birth between 1991 and 2004 and found no association between the mothers' obesity and the risk of major birth defects. However, there was a link with diabetes. "Women who had diabetes before becoming pregnant showed an almost four-fold higher risk of having a baby with a birth defect than women without the disorder, but a substantial proportion of obese patients did not know they were diabetic until they were pregnant," Biggio says.
The vast majority of babies in the study were born with no congenital defects, so the findings, published in the journal Obstetrics & Gynecology, do not mean that women with diabetes generally have a high risk of having a baby with a birth defect. Across the study period, the rate of any major anomaly was less than 1 percent among all women. Also, past research shows that well-controlled diabetes carries a lesser risk. "We have known for some time that women with pre-gestational diabetes have a lesser rate of congenital anomalies with improved blood sugar control prior to and during pregnancy," says Biggio, who was lead researcher on the study.
There are several theories on why diabetes is related to birth defects. "Excess blood sugar is delivered to the embryo early in pregnancy which may spur an overproduction of cell-damaging substances called free radicals," Biggio says, "The extra sugar may also result in metabolic byproducts that interfere with signaling mechanisms critical to embryonic development."
Learning how best to care for these expectant mothers has been a focus for Biggio and his team at UAB. "Our approach has been to identify risks, as early as possible, for adverse pregnancy outcomes," he says. "In addition, we have decreased operative risks. In the morbidly obese, 50 percent require a C-section which makes them a high risk for wound complications. We have changed our wound closure techniques to minimize that risk. Also, we encourage early ambulation and other measures to decrease thrombosis."
By confronting risks early in the pregnancy, physicians can help improve outcomes for obese mothers and their babies. Early dating of the pregnancy allows careful monitoring of fetal growth and allows better decisions regarding management to be made later in pregnancy if complications arise. "We also do early screening for gestational diabetes in these women," Biggio says. "The earlier a diagnosis of glucose intolerance is made, the better the opportunity to intervene and improve outcomes. If we wait until 26 weeks of gestation to do diabetes screening, it may be too late for these women."
Also related to the effective management of these women is the use of medical equipment that accommodates their size. The UAB Women & Infant Center has specially equipped maternity rooms designed for obese women. Tables in labor and delivery rooms and operating rooms also are available as well as patient transport stretchers and special surgical equipment.
While care for obese women during pregnancy has improved in many areas, Biggio suggests another way these women can help themselves and their babies. "We need to provide information to these mothers about breast feeding and encourage them to try it. In Alabama, the rate of breast feeding is much lower than most other states," he says. "Breast feeding offers an opportunity for these women to increase postpartum weight loss and to reduce childhood obesity. It is a benefit for both mother and child."
