Obesity in pregnant women can lead to urinary and kidney problems in developing fetuses, according to a new study. Maternal obesity has been linked to various congenital malformations, leading researchers to question whether the condition could have an effect on development of the lower digestive system.
Congenital abnormalities of the kidney and urinary tract (Cakut) make up between 20 percent and 30 percent of all prenatal abnormalities diagnosed each year, affecting roughly 1 percent of all pregnancies.
Researchers examined hospital records from 3,221 patients from around Washington state, diagnosed with Cakut. About four times as many healthy cases were also examined, working as a control group for the study. Mothers of babies with the abnormalities were 1.3 times more likely to be obese, compared with those experiencing healthy births.
"Our findings add to the public health importance of obesity, particularly as a modifiable risk factor," Ian Macumber of Seattle Children's Hospital, said.
Cakut abnormalities can include babies born with just a single kidney, or swollen organs. Ureters, the tubes that carry urine, can also be enlarged in babies.
Previous studies have shown maternal obesity can contribute to heart problems in children, as well as spina bifida and other malformations.
Although obesity was linked to the incidence of Cakut abnormalities in babies, mothers who were overweight but not obese did not show any higher instance of the malformations. The correlation between obesity and Cakut deformities does not provide any information about cause and effect. Research still not not know how obesity could contribute to the conditions, or if extreme excess weight and these conditions have the same causes. Investigators in the study believe that insulin may play a role in the malformations, by interfering with proper sugar intake by the developing fetus. It is also unknown which forms of Cakut were more common than others.
Over half of the pregnant women in the United States are overweight or obese, and roughly one in 12 are extremely obese. A body-mass index of 30 or greater is generally considered to be obese. For a woman woman measuring 5 feet, 4 inches, this equates to around 180 pounds.
Future studies could track women throughout pregnancy, watching for the warning signs of abnormalities, especially among obese mothers.
Study of the development of congenital birth defects caused by severely overweight mothers will be detailed in an address to be delivered at the ASN Kidney Week 2014. That event, to be held Nov. 11-16 in Philadelphia, is sponsored by the American Society of Nephrology.
