(Updated) Maintaining good health during pregnancy is one of the surest ways mothers can protect their developing babies’ well-being. A new study suggests that adequate levels of vitamin D could be one such protective factor.
Some data have linked low vitamin D levels to weight gain and obesity in women and children, but in the new study researchers at the University of Southampton in the U.K. found that association may begin the womb: children born to mothers with low levels of the vitamin during pregnancy had more body fat at age 6 than those whose mothers weren’t vitamin deficient.
The study, published in the American Journal of Clinical Nutrition, looked at the vitamin D levels of 977 pregnant women and the body composition of their kids. All the women were part of the Southampton Women’s Survey — one of the largest women’s surveys in the U.K.
“In the context of current concerns about low vitamin D status in young women, and increasing rates of childhood obesity in the U.K., we need to understand more about the long-term health consequences for children who are born to mothers who have low vitamin D status,” lead researcher Dr. Siân Robinson said in a statement.
How vitamin D in mothers affects their children’s weight gain remains unknown, but the authors speculate that there are “programmed effects on the fetus that arise from maternal vitamin D insufficiency that remain with the [baby] and that may predispose him or her to gain excess body fat in later childhood.”
The researchers add that childhood weight gain can also be attributed to other issues associated with insufficient maternal nutrition like too much or too little weight gain by pregnant mothers.
Previous research has shown low vitamin D levels can lead to other pregnancy complications. A 2010 study found that women who developed a severe form of pregnancy-related high blood pressure called early-onset severe preeclampsia had lower vitamin D levels than healthy pregnant women. The complication is more common among African American women, who are also more likely to be vitamin D deficient; vitamin D is naturally synthesized in the skin when exposed to sunlight, and the process is less efficient in people with darker skin.
A 2012 nutrition report from the Centers for Disease Control and Prevention (CDC) reported the highest rates of vitamin D deficiency are among non-Hispanic blacks.
The National Institutes of Health says everyone can get vitamin D from enhanced foods, sun exposure and dietary supplements. Vitamin D is present naturally in very few foods, including:
- Eggs (in yolks)
The new study is part of a larger project by the University of Southampton’s MRC Lifecourse Epidemiology Unit, which investigates how factors during pregnancy may influence childhood growth and development long-term.
Clarification [June 1]: Although swordfish is a good natural source of vitamin D, this article should have explicitly noted that it is also high in mercury and, therefore, not safe for pregnant women to consume. Exposure to mercury in pregnancy is linked to brain damage and development problems in children. Other fish high in mercury that pregnant women should avoid include shark, king mackerel and tilefish. For more information, see the EPA’s advisory here.