Vitamin D and Pregnancy

Vitamin D deficiency in children can cause a serious bone deformity called rickets, which results in deformed, curved legs and other bone malformation. So clearly, adequate vitamin D intake is essential for pregnant women and infants, and the current recommendation for pregnant women is 600 IU per day. This is also the recommendation for women who are lactating, and infants up to 1 year old should receive 400 IU per day as well.

Can extra vitamin D be advantageous for pregnancy?

There is at least some evidence that it can. Some recent research suggests that pregnant women who take up to 4000 IU per day may reduce the risk of serious complications during their pregnancy. The researchers found decreased risk of preeclampsia, a condition of high blood pressure during pregnancy, with 4000 IU of vitamin D. And premature birth was decreased as well.

Many researchers suggest that taking that high of a dose during pregnancy is unneccessary and possibly even risky, but the researchers involved did not think there was a serious risk involved. This issue remains contentious. The upper tolerable level for pregnant women is 4000 IU, and so they should not go above this at the very least.

In opposition to the above, a 2011 meta-study (a study of other studies) found no effect from extra vitamin D supplementation. It found that low levels of D are the norm with pregnant women, and there was no correlation with higher levels and risk of pregnancy complications.

So, clearly, as with much scientific research, the jury is still out. It is not proven that large doses of vitamin D during pregnancy will help reduce birth complications or not. The best bet is probably to make sure you get the recommended allowance of 600 IU per day during pregnancy and lactation, per the RDA.