BMI

Increased BMI Before Pregnancy Linked w/ Heart Defects in Infants

We have had a major push in obstetrics for folic acid and yet there are many factors that contribute to a healthy pregnancy. Folic acid is important, but avoidance of toxins such as pesticides can be equally important. Healthy levels of multiple vitamins and minerals such as calcium and zinc. Avoidance of exposure to heavy metals such as mercury in tuna fish. Now we see that a lower body mass index may contribute to a healthier pregnancy as well.

Epidemiology 2001;11:439-446 Women who are overweight or obese before conception appear to have an increased risk of giving birth to infants with isolated heart defects, researchers from the US Centers for Disease Control and Prevention in Atlanta report in the July issue of Epidemiology. Using data from the Atlanta Birth Defects Case-Control Study, Drs. Margaret L. Watkins and Lorenzo D. Botto studied heart defects in 851 live and stillborn infants, among whom 608 had an isolated heart anomaly. The researchers compared these infants with data from 2767 infants without heart defects (controls). Study data were collected for infants born between 1968 and 1980, with interviews of parents conducted between 1982 and 1983. The researchers found that compared with infants of average-weight women, infants of underweight women (body mass index [BMI] < 16.5) were less likely to have to have a major isolated heart defect (adjusted odds ratio 0.64). In addition, compared with average- or underweight mothers, the investigators found that overweight and obese women were more likely to have an infant with a major isolated defect. Among women with a BMI of 26 to 29, the adjusted odds ratio was 1.41, and for women whose BMI was above 29, the adjusted odds ratio was 1.29. This trend toward an increase in isolated heart defects with increased maternal BMI was not present when the investigators looked at multiple heart defects. For isolated heart defects, they note that the adjusted odds ratio per unit of BMI was 1.02, while for multiple defects it was 1.00. In addition, Drs. Watkins and Botto report that “mothers of infants with heart defects were less likely to be white and less likely to report periconceptional vitamin use,” and that infants born during the later years of the study were more likely to have heart defects. Although the reason for the relationship between prepregnancy weight and isolated heart defects is unknown, “if the association between maternal weight and heart defects is real, it has important implications for prevention, given the increasing prevalence of obesity and the morbidity and mortality association with heart defects,” Drs. Watkins and Botto conclude.