By Nathan Seppa, Science News
Children born to women who have achieved drastic weight loss through stomach surgery are healthier than children born to severely obese moms, a new study shows. The findings suggest that obesity creates an unhealthy environment for a fetus that has ramifications later on, scientists report in the November Journal of Clinical Endocrinology & Metabolism.
“This is very important work,” says Dana Dabelea, a physician and epidemiologist at the University of Colorado–Denver and the Colorado School of Public Health in Aurora. “This is the first proof that exposure to obesity in utero is associated with long-term effects,” she says.
Severely obese women should be encouraged to lose weight before becoming pregnant, asserts study coauthor John Kral, a surgeon at the State University of New York Downstate Medical Center in Brooklyn. Obese women who are interested in having kids and getting weight-loss surgery at some point in their lives should get the surgery first, he says.
Kral collaborated with researchers at University of Laval in Quebec City in contacting 49 women who had given birth and had also undergone a specific type of obesity surgery. About half of the women had one child before surgery and another child after.
All the women had undergone biliopancreatic diversion bariatric surgery, in which a portion of the stomach is removed and food and digestive enzymes are shunted past part of the small intestine, limiting the amount of nutrients absorbed. On average, the women lost more than one-third of their body weight after surgery, and they kept it off. Thus, the women went from being severely obese to slightly overweight.
The surgeries took place between 1984 and 2005. During that time, these women had a combined total of 111 children—54 born before obesity surgery and 57 afterward. When the children were examined in 2007 and 2008, they ranged in age from 2 to 25 years.
The researchers found that 19 children born before their moms underwent surgery were severely obese, compared with six children born after surgery.
As a group, the children born after surgery scored better on a host of medical tests. Blood tests revealed that those born after surgery had healthier levels of leptin and ghrelin, hormones that regulate appetite. These children also used insulin more efficiently. This hormone regulates how cells process sugars, and children born to women after weight-loss surgery had less evidence of insulin resistance, which can a precursor to diabetes.
Measurements of overall HDL cholesterol, the good kind, were higher in children born after surgery, and their total-cholesterol-to-HDL ratio was lower.
Children born after mom had obesity surgery also had lower blood levels of C-reactive protein, a marker of low-grade, chronic inflammation.
These scores reveal a person’s risk of cardiovascular disease, stroke and other health risks, Kral says.
The new data suggest that a fetus can undergo epigenetic changes in the womb brought on by maternal obesity, Kral says. “Any number of genes are potentially modifiable in the intra-uterine environment,” he says, including genes that guide metabolism.
Meanwhile, the cause of obesity itself is unclear. Obesity probably has a genetic component, Dabelea notes, and is easily influenced by overeating and a sedentary lifestyle. But she adds that programming caused by maternal obesity during fetal development is another important mechanism. “How this programming operates—what exactly happens in these exposed offspring—we don’t know.”
What’s more, earlier animal experiments suggest that “maternal obesity actually resets the satiety balance point” in the fetus, Dabelea says, so that offspring need to eat more to feel full.
In a departure from past generations’ medical dogma, she adds, doctors are starting to counsel women to maintain only modest weight gain during pregnancy and should ask obese women to lose weight while pregnant.