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Information on the latest vitamin D news and research.

Find out more information on deficiency, supplementation, sun exposure, and how vitamin D relates to your health.

RCT: High-dose vitamin D3 safe during pregnancy

A new randomized controlled trial shows once again, high-dose vitamin D during pregnancy is safe and effective at raising vitamin D blood levels for mother and newborn child. The recent randomized controlled trial was published in the Nutrition Journal.

Lead author Daniel Roth, MD, and colleagues administered vitamin D or placebo to pregnant women aged 18 to 25 years from Bangladesh. The supplementation started at some point during their third-trimester of pregnancy and lasted until birth. They randomly assigned 130 women to take 35,000 IU of vitamin D per week or to take a placebo pill. The women on average took supplements for about 10 weeks, or until delivery.

Maternal vitamin D status at baseline was similar for the vitamin D and placebo groups: 18 and 17 ng/ml respectively. At delivery, the vitamin D group had a mean 25(OH)D level of 52 ng/ml, while there was a slight decrease for mothers in the placebo group (from 17 ng/ml to 15 ng/ml). The newborn babies had similar differentials. Those with mothers in the placebo group had a mean 25(OH)D level of 15 ng/ml, while those with mothers in the vitamin D group had a mean of 41 ng/ml.

Mean calcium concentration rose over time, within the reference range, in both groups. According to past research, it is common for calcium levels to increase during the 3rd trimester. There were no cases of hypercalcemia in either group.

The authors reported that there were no differences between the vitamin D and placebo groups in adverse birth outcomes. However, the number of enrollees may have been too small to see an effect.

The current research confirms previous study findings that high dose vitamin D is safe and effective at raising vitamin D levels during pregnancy. Drs Hollis and Wagner have previously studied the effects of up to 2,000 and 4,000 IU of vitamin D per day during pregnancy and have found similar trends: that 4,000 IU/day is safe and adequately raises vitamin D levels in pregnant mothers and their newborns compared to control groups.

In fact, Hollis has gone as far as to say that the RDA during pregnancy should be raised to 4,000 IU/day, a recommendation that Roth and colleagues weren’t quite ready to make. They call for further clinical data before “conclusive statements” can be made regarding vitamin D supplementation for women during pregnancy.

It’s worth noting that while this randomized controlled trial was safe and effective during the third trimester, it’s unclear at this time if the newborns from the vitamin D group will be healthier, the same, or worse off than the placebo group in years to come. There is a general lack of data from randomized controlled trials demonstrating how vitamin D supplementation during pregnancy effects the health of newborns. These kind of trials are underway and will provide much needed insight in the near future.

For the time being, there are some observational data that higher vitamin D levels during pregnancy will lead to better health outcomes for newborns compared to low levels. From what we currently know about vitamin D, there is reason to believe higher supplementation during pregnancy, like in this Roth et al study and past Hollis/Wagner studies, could potentially lead to better health outcomes.

What do you think? Do you think we have enough evidence to raise the vitamin D RDA for pregnant women or do we need more data from RCTs?


Roth DE, Mahmud AA, Raqib R, Akhtar E, Perumal N, Pezzack B, Baqui AH. Randomized placebo-controlled trial of high dose prenatal third-trimester vitamin D3 supplementation in Bangladesh: the AViDD trial. Nutrition Journal. 2013.

  About: Kate Saley

Kate was the Community Coordinator for the Vitamin D Council between 2012-2013. She oversaw the Council’s social media, blog, newsletter and membership base. Kate is currently going to school for occupational therapy.

4 Responses to RCT: High-dose vitamin D3 safe during pregnancy

  1. Rita and Misty says:

    Greetings Kate,

    This is a very well written article…a pleasure to read. Thank you.

    I think that the newborns from the vitamin D group may very well be healthier than the placebo group in years to come, in particular if the children from the placebo group never raise their vitamin d levels to optimal.

    It would be interesting to chart the health of the children from the Vitamin D group over many years…

    Regarding the vitamin D RDA for pregnant women:

    I think that RDA should be dropped and 25(OH)D level should be the only thing that counts!

    Everyone needs to maintain vitamin d serum levels of above 50 ng/ml for optimal health.

    IMO :)

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  2. Rebecca Oshiro says:

    I agree with Rita’s comment about dropping the RDA and focusing on the 25(OH)D level, but unfortunately the policy wonks need generalized recommendations they can make to the public as a starting point.

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  3. Rita and Misty says:

    I know…I work in a place that is literally paralyzed by policy..protocol..and bureaucracy….

    It is painful…

    Some days my head spins from the lunacy of it all, and all I can say is WOW…

    Thank goodness for the Vitamin D Council.

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  4. Rebecca Oshiro says:

    Amen to that!

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