URBANA — Obesity isn't just unhealthy for an expectant mother. It puts her baby at risk for future health problems, even when the mom eats a healthy diet during her pregnancy, a new University of Illinois study has found.
Women who are obese need to reduce their weight to a healthy level before they become pregnant, warns Yuan-Xiang Pan, a UI professor of molecular nutrition and the principal author of the study.
"They will have a much healthier baby," he said.
The issue of maternal obesity has been a health concern growing along with obesity worldwide, Pan said.
One-third of all women of child-bearing age in the U.S. are considered obese, and since the mid-1990s, half of all American women in the U.S. of child-bearing age are overweight, his study said.
Pan and co-author Rita Strakovsky of the UI's Division of Nutritional Sciences conducted their research by comparing the placentas of two groups of pregnant rats — some obese and some obesity-resistant — fed the same healthy diet.
The placenta is the critical link between mother and child, transferring nutrients and oxygen from mother to child and waste from child to mother through the blood.
While the two groups ate the same diet and obese mothers didn't gain much weight, the environment for the baby in obese mothers was unhealthy and the transport of nutrients from mother to baby was affected, Pan said.
The obese moms had higher levels of triglycerides fatty acids (both types of fat) in their circulation, he said. They also had extra fat accumulating in their placentas that was needed by the baby to support its growth. And the nutrient supply area of the placenta was smaller.
Children of obese mothers were born up to 17 percent smaller than they should have been, and their lower birth weights leave them more vulnerable to potential health problems down the road, Pan said.
Other studies have linked low birth weight with increased occurrence of type 2 diabetes, hypertension and obesity later in life.
While the study was conducted with rats, Pan said, human and rat placentas are very similar, and it's "highly likely" the effects would be the same in human moms.
Current recommendations for pregnant women focus on controlling weight gain during pregnancy, but increased evidence indicates the weight women gain before they become pregnant is just as important to gestational and fetal health as the weight gained during the pregnancy, the study advises.
The research was supported by the USDA Cooperative State Research, Education and Extension Service and was published in the March issue of Biology of Reproduction.
Pan says he plans to follow up with more research to see if putting obese mother rats on a diet prior to pregnancy makes a difference by changing the blood chemistry and pathology of the placenta.
A separate study published online earlier this week in Pediatrics found children born to obese mothers have a higher chance of being diagnosed with autism or other developmental delays than those born to women at healthy weights.