SPS



Q&A 329.3

Which oral vitamin D dosing regimens correct deficiency in pregnancy?

Prepared by UK Medicines Information (UKMi) pharmacists for NHS healthcare professionals

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Date prepared: June 2016

Summary

• A re-emergence of rickets has been seen in the UK, with cases mainly affecting children from ethnic minorities; this is probably related to both maternal and infant diet and lifestyle in particular groups (for example, in women who cover their skin).

• Women should have adequate vitamin D stores for their own requirement, for their developing foetus and to build stores for early infancy particularly if they plan to breast-feed.

• During pregnancy, maternal vitamin D deficiency (defined here as less than 30nmol/L) can lead to deficiency in the infant

• Testing: There is no consensus on exactly which pregnant women to test for vitamin D deficiency but there is an argument that some groups of women who are pregnant should have screening test: for example, on the basis of skin colour, obesity or risk of pre-eclampsia. If a pregnant woman is tested for deficiency and found to be deficient, then consideration should be given to correcting this deficiency. 

• Safety: Vitamin D use in human pregnancy is not associated with an increased risk of congenital malformation, although the data are insufficient to confirm that there is unequivocally no risk. In the general population, an upper physiological limit of 10,000units of vitamin D/day has been suggested. Above this daily dose, adverse effects are theoretically more likely so bolus injections or oral doses of more than 10,000units per day should be avoided and very high single bolus doses (i.e. 300,000-500,000units) should not be used in pregnancy. Safety data relate to use in the second or third trimesters and use of high dose vitamin D in the first trimester should be avoided.

• Dose for correction (vitamin D 50 nmol/L to be adequate whilst some suggest >75nmol/L [pic](4;6;13-16); with deficiency being represented by a serum 25OHD level of 25,000units; and the French Society of Paediatrics recommends large single doses up to 80,000–100,000units, but only from the 7th month of pregnancy. [pic](21;22)

In addition to national guidance we identified a number of systematic reviews which summarised the available literature on vitamin D use in pregnant women. [pic](4-7;23) The studies included varied in design; duration; doses and products of vitamin D used; latitude, ethnicity, and sun exposure habits of participants; baseline maternal vitamin D levels and assay methods used to determine 25OHD. The range of doses investigated in the studies reviewed also varied significantly. [pic](5-7;23) The highest daily dose studied in pregnancy was: 4000units/daily and the highest single weekly and monthly dose was: 50,000units/week, 100,000units/month respectively. [pic](5;23) Single bolus doses used in later pregnancy ranged from: 60,000units to 600,000units. (5;7) The cumulative doses to which patients were exposed also varied significantly: 56,000 – 1,200,000units, given as 600,000unit doses at the 7th and 8th months in one study, and with no adverse pregnancy outcomes reported for this range. [pic](4;7;24)

Further interventional studies published since the systematic reviews were also highly variable with respect to oral vitamin D dosing which ranged from 400-4000units/day to a high dose of 50,000units/week. [pic](8;25-31) One study is a multicentre, double-blind, randomised, placebo controlled trial conducted in the UK. Over 500 pregnant women, with baseline serum vitamin D levels of 25-100 nmol/L, were supplemented with 1000units/day of oral colecalciferol from weeks 14 to term which safely repleted mean maternal vitamin D levels to 67.8nmol/L. However, as the mean baseline vitamin D levels were 46nmol/L, the results are not entirely applicable to patients who are deficient ( ................
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