Read: Vit D deficiency causes small babies
In one of the largest studies to date, researchers studied blood samples collected from 700 pregnant women who later developed pre-eclampsia in an effort to examine a woman’s vitamin D status during pregnancy and her risk of developing pre-eclampsia. The full study, funded by the National Institutes of Health (NIH), is available online in the journal Epidemiology.
“For decades, vitamin D was known as a nutrient that was important only for bone health,” said lead author Lisa Bodnar, PhD, MPH, RD, associate professor in Pitt Public Health’s Department of Epidemiology. “Over the past 10 to 15 years, scientists have learned that vitamin D has diverse functions in the body beyond maintaining the skeleton, including actions that may be important for maintaining a healthy pregnancy.”
Factors that affect vitamin D status
Dr Bodnar and her colleagues also studied blood samples from 3 000 mothers who did not develop pre-eclampsia. The samples were collected between 1959 and 1965 at 12 US sites enrolled in the Collaborative Perinatal Project. The blood was well-preserved, and researchers were able to test for vitamin D levels decades later.
Scientists controlled for factors that could have affected a woman’s vitamin D status, including race, pre-pregnancy body mass index, number of previous pregnancies, smoking, diet, physical activity and sunlight exposure, which is the body’s primary source of vitamin D.
The researchers found that vitamin D sufficiency was associated with a 40% reduction in risk of severe pre-eclampsia. But there was no relationship between vitamin D and mild pre-eclampsia. The overall risk of severe pre-eclampsia in the women sampled was 0.6 %, regardless of vitamin D status.
“Scientists believe that severe pre-eclampsia and mild pre-eclampsia have different root causes,” said senior author Mark A Klebanoff, MD., M.P.H., Centre for Perinatal Research at The Research Institute at Nationwide Children’s Hospital and the Department of Paediatrics at The Ohio State University College of Medicine. “Severe pre-eclampsia poses much higher health risks to the mother and child, so linking it with a factor that we can easily treat, like vitamin D deficiency, holds great potential.”
“If our results hold true in a modern sample of pregnant women, then further exploring the role of vitamin D in reducing the risk of pre-eclampsia would be warranted,” said Dr Bodnar. “Until then, women shouldn’t automatically take vitamin D supplements during pregnancy as a result of these findings.”