Prevention of Adverse Pregnancy Outcome With Vitamin D Supplementation During Pregnancy

Vitamin D deficiency has been associated with many chronic diseases. These include cardiovascular diseases, diabetes mellitus, multiple sclerosis, breast and prostate cancers. Recently, its role in pregnancy has been explored. Vitamin D deficiency has been found to be associated with adverse pregnancy outcome. These include pre eclampsia, gestational diabetes mellitus, preterm labor and low birth weight.

Bodnar et al, evaluated role of vitamin D deficiency during pregnancy in PE in a nested case control study. The investigators looked at the role of vitamin D at gestational age of < 22 weeks. Women who developed PE were found to have low levels of vitamin D. These women had serum levels of vitamin D < 15 ng/ml, were supplemented during pregnancy with prenatal vitamins, were still found to have 5 fold greater chances of developing PE (adjusted odds ratio, 5.0; 95% confidence interval, 1.7-14.1).Children of above group of women were also found to have low levels of vitamin D. The authors concluded that vitamin D deficiency may be an independent factor for the development of PE.(1)

In an epidemiological study from Norway, involving 23,423 primigravidae, the rsik of PE was found to be 27% greater in women who did not receive D supplements, compared to women who received 10-15µg/day of vitamin D(2).

Circulating levels of 1-25(OH) have been found to be low in women with PE.(3) This has been attributed to reduced expression and activity of 1α-hydroxylase in human placenta from preeclamptic pregnancies.(4) This association with PE has also been found to be influenced by VEGF (Vascular endothelial growth factor). Active forms of vitamin D have been found to increase the expression of VEGF , and its release in vascular smooth cells, in in-vitro studies.(5)

Vitamin D deficiency has also been associated with small for gestational age (SGA) (6) The difference has been found to be more subtle for Caucasians as compared to African-Americans in West. The investigators showed a U shaped association between D levels and SGA. After confounder adjustment, compared with serum 25(OH)D 37.5-75 nmol/L, SGA odds ratios (95% CI) for levels <37.5 and >75 nmol/L were 7.5 (1.8, 31.9) and 2.1 (1.2, 3.8), respectively. In a similar study by Brooke, among Asian women resident in UK, vitamin D supplementation with 1000IU in third trimester, compared with placebo, was associated with decreased incidence of small for gestational age (15% versus 29%). Investigators suggested supplementation with vitamin D among Asians living in UK.(7)