Studies have shown that obese women give birth to larger babies who are at risk for obesity and other metabolic problems later in life. Some have thought that the reason may be that obese mothers, whose bodies are rich in nutrients, somehow “overfeed” the fetus during gestation. A new study has found that this is unlikely.
The study, in PLOS Medicine, looked at more than 10,000 mother-child pairs, following their offspring into early adulthood. Researchers had data on body mass index, education, occupation and smoking behavior for both mothers and fathers. They also did tests for 153 metabolic traits in the children, including levels of fats in the blood.
They found that both maternal and paternal B.M.I. were associated strongly with the metabolic traits of their children. Since paternal B.M.I. cannot affect the fetus during its development, this suggests that familial traits, rather than any “programming” of the fetus in the womb, are the explanation for metabolic abnormalities in the children of obese mothers.
The senior author, Deborah A. Lawlor, a professor of epidemiology at the University of Bristol in England, said obesity in pregnancy is dangerous for many reasons. But the evidence that the mother’s weight alone determines her children’s future metabolic health is weak, and putting all the burden on the pregnant woman is not helpful.
“The whole family should have a healthy weight,” she said.