Low Doses Of Vitamin D Linked With Harmful Outcomes During Pregnancy

A link has been found between adverse health outcomes and vitamin D deficiency resulting in complications such as gestational diabetes and preeclampsia in pregnant women and low birth weight in newborns.

Vitamin D deficiency has already been linked to several health problems and has been flagged as a public health concern. Additionally, observational data have suggested that vitamin D deficiency is linked to harmful outcomes during pregnancy, such as:

• risk of infections
• preeclampsia
• gestational diabetes
• fetal growth restriction
• cesarean section
• low birth weight for newborns

Last year, a study reported that elevated levels of vitamin D during pregnancy could later prevent multiple sclerosis in the mothers.

The investigators from the University of Calgary in Canada analyzed systematically all existing evidence on the impact of vitamin D levels on pregnancy and birth outcomes.

Data were taken from 31 studies published between 1980 and 2012 ranging from 95 to 1,100 participants. Study design and quality differences were accounted for to limit bias.

Results of the current study, published in BMJ, revealed that pregnant women with low levels of 5-OH vitamin D were more likely to develop preeclampsia, had an elevated risk of giving birth to a baby small for gestational age, and were at an increased risk of having gestational diabetes.

Vitamin D levels during pregnancy were not found to be associated with any impact on a baby's length at birth or head circumference.

The authors note that these results are "concerning" because of evidence showing that vitamin D deficiency is common during pregnancy, specifically in women at higher risk, including:

• those with limited sun exposure
• vegetarians
• ethnic minorities with darker skin

The researchers conclude that their outcomes present a noteworthy link, however, large well-designed randomized controlled trails are needed to find whether "strategies to optimize vitamin D concentrations are effective in improving pregnancy and neonatal outcomes."

Dr Lucas, from the National Centre for Epidemiology and Population Health at the Australian National University, in an Accompanying Editorial said that the results of this study provide strong evidence that vitamin D sufficiency should be a goal for all pregnant women. She said, "supplements, diet and sunlight exposure" are all influences which "should be used together, with care."

Written by Kelly Fitzgerald