Low folate during pregnancy associated with childhood obesity risk

Nutrition during pregnancy can have life-long effects on the child’s health. pixelheadphoto/iStock/Thinkstock

A mother’s health during pregnancy can have life-long effects on her child’s health. Babies born to obese mothers, for example, are known to have a higher risk of obesity in childhood. This link is thought to have a variety of biological and environmental influences.

Obese mothers are more likely to have insufficient folate levels than normal weight mothers. Folate is an essential B vitamin that is required for many metabolic processes. A team led by Dr. Xiaobin Wang at Johns Hopkins University investigated whether maternal folate levels might be connected to a child’s future metabolic health and risk of obesity. The study was funded in part by NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD). Results were published in JAMA Pediatrics on June 13, 2016.

The researchers investigated health outcomes of mothers and children in the Boston Birth Cohort, a predominately low-income, minority population (67% black, 19% Hispanic) with a high prevalence of maternal and child obesity. Mothers’ folate levels were measured 2 to 3 days after delivery. Children had at least 1 well-child care visit at 2 to 9 years-old. The team analyzed questionnaire data and health records from more than 1,500 mother-child pairs. They assessed factors that can influence obesity, including maternal smoking, education level, stress level during pregnancy, diabetes, and child breastfeeding history.

The mothers’ body mass index (BMI, a ratio of weight to height) was separated into 3 groups: normal, overweight, and obese. The children were measured during the well-care visits and divided into 2 groups by BMI: overweight/obese (39%) or non-overweight/obese (61%). Overweight or obese children had higher birth weights, rates of formula feeding, and rates of maternal obesity and diabetes.

Obese mothers tended to have lower folate levels than normal weight mothers (average 12.3 ng/ml vs 13.5 ng/mL). Overall, about a quarter of mothers fell within the lowest quartile for folate levels (below 9 ng/mL). Children of those in this low folate group had an elevated obesity risk (1.45 fold higher than those with “adequate” folate levels of at least 9 ng/mL). The children of obese mothers with low folate levels had a risk of obesity about 3-fold greater than those of normal weight moms with adequate folate levels.

Among children of obese mothers, those whose mothers had adequate folate levels had a 43% lower risk of obesity than those whose mothers had inadequate levels. This reduced risk had a ceiling effect; additional folate didn’t show additional benefits. Children of mothers with lower folate levels also had less favorable blood levels of metabolic hormones, such as insulin and leptin.

“Given the important role of folate, it would be worthwhile for physicians to check folate levels in obese women,” Wang says. More research will be needed to determine optimal levels for long-term health outcomes. Women who are pregnant should consult with a doctor on how much folate to take, as either too little or too much folate may be harmful.