The Cochrane collaboration first published a review on vitamin D in pregnancy in 2012. This was updated in 2016 and a 2019 update has just been published, which contains important changes deriving from the publication of new research studies. This updated review now includes the results of 30 trials which have involved 7033 women. The authors have looked at different combinations of supplements and compared these with a placebo or with no intervention, so the findings are complex, but here’s a helpful summary of the conclusions and changes from the Cochrane website:
- “Supplementation with vitamin D alone (22 trials in total, 13 new trials added in this update) during pregnancy probably reduces the risk of pre‐eclampsia, gestational diabetes and low birthweight.
- Supplementation with vitamin D + calcium (9 trials in total, three new trials added in this update) during pregnancy probably reduces the risk of pre‐eclampsia but may increase the risk of preterm births.
- Supplementation with vitamin D + other nutrients (1 trial trial added in this update) in pregnancy may make little or no difference in the risk of preterm birth or low birthweight.
- In general, more data are needed to conclude about the risk of maternal adverse events.” (Palacios et al 2019).
The authors of this study offer a clear and useful discussion of what kinds of research are needed in order to look into this further, and they also note that they are undertaking a related review of this topic. If you are involved in the care of pregnant women who may be offered vitamin D, I would highly recommend having a look at the review in more depth.
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