Vitamin D helps in the regulation of calcium and phosphorous in the body, which is critical to maintaining the health of bones, teeth, and muscles. But there’s no clear evidence that suggests the effect of vitamin D supplementation in pregnant women. This study aims to assess the association of vitamin D with the risk of pregnancy-related hypertensive disorders, like pre-eclampsia and gestational hypertension.

This is a mendelian randomization analysis that included a total of 7,389 women, including 3,388 pre-eclampsia cases and 6,059 controls. The exposures in the study were single nucleotide polymorphisms associated with vitamin D synthesis. The primary outcome of the study was pregnancy-related hypertensive events: pre-eclampsia and gestational diabetes. 

The conventional multivariable analysis suggested that the relative risk of pre-eclampsia 1.03 per 10% decrease in 25-hydroxyvitamin D levels, and 2.04 for 25-hydroxyvitamin D levels greater than 25 nmol/L when compared with 75 nmol/L. However, this mendelian randomization analysis did not provide enough evidence of a linear relationship between 25-hydroxyvitamin D and the risk of pre-eclampsia or gestational hypertension.

The research concluded that no strong evidence was found to determine the direct effect of vitamin D on the increased risk of pre-eclampsia or gestational hypertension.

Ref: https://www.bmj.com/content/361/bmj.k2167