Children whose mothers had their last trimester of pregnancy during the sunnier months of the year tended to have larger bones. The scientists explained this as likely being due to those mothers’ greater levels of vitamin D, which is naturally manufactured in the skin when it’s exposed to sunlight.
In the study, the researchers chose 6,995 British children who participated in a long-term health study. The scientists looked at their bone scans, and correlated them with local meteorological data suggesting the mothers’ degree of sun exposure during their last trimester. They found that children of mothers who got more sun were likely to have larger bones.
The findings are important because the stronger one’s bones in early life, the less the risk of fracture later in life. If the strength and health of the bones of the benefited children persist into adulthood, the authors said, then that same benefit might last into old age.
While pregnant mothers shouldn’t overdose on sun exposure, since UV rays are known to increase the risk for skin cancer, the results offer “further justification for strategies intended to improve maternal vitamin D status to optimize skeletal health in the child,” wrote researchers Adrian Sayers and Jonathan H. Tobias of the University of Bristol.
To get sufficient vitamin D, women and others should get a few minutes of sun exposure as often as possible, and consume milk and breakfast cereals fortified with vitamin D. Among the few foods that naturally contain the vitamin are salmon, mackerel and tuna. The daily amount of vitamin D during pregnancy that’s officially recommended is 200 IU per day, though this is still under discussion. Studies have shown that pregnant women are frequently deficient in vitamin D.