A Cochrane meta-analysis finds several obstetrical complications are helped by supplementing with vitamin D during pregnancy.
Cochrane meta-analyses are considered the highest standard of proof in medicine. One was recently published about vitamin D during pregnancy and subsequent adverse birth events.
De-Regil LM, Palacios C, Lombardo LK, Peña-Rosas JP. Vitamin D supplementation for women during pregnancy. Cochrane Database Syst Rev. 2016 Jan 14;1:CD008873. doi: 10.1002/14651858.CD008873.pub3. Review. PMID:26765344
Most of the daily doses used were between 400 to 600 IU, or given as bolus doses rather than daily. In spite of that, the analysis found reasonable evidence that vitamin D supplementation during pregnancy appears to reduce the incidence of pre-eclampsia, low birth weight and preterm delivery. The authors excluded the work of Carole Wagner and Bruce Hollis for unclear reasons, but still found significant benefits of women taking extra vitamin D during pregnancy.
The authors concluded:
“In this review update, new studies have added to the evidence base on the effects of supplementing pregnant women with vitamin D alone or with calcium on pregnancy outcomes. Supplementing pregnant women with vitamin D in a single or continued dose increases serum 25-hydroxyvitamin D at term but the results were highly variable. Supplementation with vitamin D and vitamin D plus calcium appears to reduce the risk of pre-eclampsia and vitamin D supplementation appears to reduce the risk of low birth weight and preterm delivery. However, it appears that when vitamin D and calcium are combined, the risk of preterm birth is increased.”
But then they added:
“The evidence on whether vitamin D supplementation should be given as a part of routine antenatal care to all women to improve maternal and infant outcomes therefore remains unclear. While there is some indication that vitamin D supplementation could reduce the risk of pre-eclampsia and increase length and head circumference at birth, further rigorous randomized trials are required to confirm these effects. Currently, the number of high quality trials with large sample sizes and outcomes reported, including data on adverse effects, is too limited to draw definite conclusions on its usefulness and safety.”
More research is needed, once again. This means a meager 400 or 600 IU of vitamin D will remain in prenatal vitamins, which also means a number of birth complications could be prevented if pregnant women would just take 5,000 to 10,000 IU/day. This may sound like a lot, but remember it is only 125 and 250 mcg, respectably. 10,000 IU/day sounds like too much but 250 mcg/day does not. It’s the exact same dose.
Also, remember that physicians, including obstetricians, are ethically obligated to act on the best scientific evidence that exists. If you’re pregnant and your obstetrician will not get your vitamin D level up to between 40 and 60 ng/ml, as the Endocrine Society recommends, simply go on our website and order your own vitamin D blood test. Then spend some time on our website to decide how much vitamin D you want to take.
Remember in the Wagner and Hollis lactation study, the ethics committee made them terminate the 2,000 IU/day arm in lactating mothers for ethical reasons because 2,000 IU/day was an insufficient dose to raise the 25(OH)D of the nursing infants to above 30 ng/ml.
We recommend pregnant and lactating women take between 5,000 to 10,000 IU/day. It is very important to make sure that your vitamin D level is above 40 ng/ml. Taking one of our in-home vitamin D tests is so simple; every pregnant and lactating woman should do it.