Vitamin D in pregnancy

Vitamin D supplementation in pregnancy and breastfeeding

All women should be informed at the booking appointment about the importance for their own and their baby's health of maintaining adequate vitamin D stores during pregnancy and whilst breastfeeding (1,2).

In line with UK government guidance, advise anyone who is pregnant or breastfeeding about the following (1):

• they should take a vitamin D supplement (10 micrograms or 400 international units [IU] a day) between October and March (because the body produces vitamin D from direct sunlight on the skin, and between October and early March, the sun is not strong enough for the body to make enough vitamin D).
• they should take vitamin D (10 micrograms or 400 IU a day) throughout the year if they are at increased risk of vitamin D deficiency because they, for example:
  • have darker skin, such as people of African, African-Caribbean or south Asian ethnicity, because they may need more sunlight exposure to produce the same amount of vitamin D as people with lighter skin pigmentation or
  • have little or no exposure to sunshine because they are not often outdoors or usually wear clothes that cover up most of their skin when outdoors.

Women who are not eligible for the Healthy Start benefit should be advised where they can buy the supplement.

NHS Specialist Pharmacy Service guidance with respect to vitamin D supplementation in breastfeeding states (3):

• Forms of vitamin D used during breastfeeding
  • vitamin D is available in many different forms
    • Colecalciferol (vitamin D3) or ergocalciferol (vitamin D2) are the two main vitamin D compounds used for the treatment and prevention of vitamin D deficiency
    • general guidance on the Safety considerations when using Vitamin D is available
    • for other forms of vitamin D (including alfacalcidol, calcipotriol, and calcitriol), please contact specialist service for further advice
      
• With respect to doses of vitamin D in breastfeeding
  • prevention/supplement doses (usually 400 units daily)
  • maintenance doses (up to 4000 units daily) where treatment of vitamin D deficiency is not considered urgent or maintenance therapy is required. Maintenance doses up to 4000 units daily can be used during breastfeeding and do not require any infant monitoring
  • loading doses (above 4000 units daily) where the treatment of vitamin D may require rapid correction
    • will usually not exceed a cumulative total dose of 300,000 units divided into daily or weekly dosing over a maximum of 10 weeks
    • loading doses can be administered as various dosing schedules; examples include 50,000 units once weekly for 6 weeks, or 4000 units daily for 10 weeks
      
• Considerations for infant monitoring if maternal vitamin D supplementation:
  • infant monitoring side effects are generally not expected in breastfed infants, and therefore no specific infant monitoring is required when maintenance doses up to 4000 units daily are being used
    • however, as a precaution, monitor the infant for any unusual sign or symptoms
    • when loading doses are being used, the infant should be monitored for signs of hypercalcaemia as a precaution, including increased wet nappies, lethargy, gastrointestinal disturbances, and changes in feeding
      • infants should also be monitored for irritability and skin reactions
      • infant calcium levels should be monitored if:
        • hypercalcaemia is suspected due to infant symptoms
        • loading doses above 300,000 units as the total treatment course are required
        • treatment courses longer than 10 weeks are required

For detailed advice then see NHS Specialist Pharmacy Service - Using vitamin D during breastfeeding.

Note:

• a systematic review concluded that "Supplementing pregnant women with more than the current vitamin D recommendation may reduce the risk of gestational diabetes; however, it may make little or no difference to the risk of pre-eclampsia, preterm birth and low birthweight. Supplementing pregnant women with more than the current upper limit for vitamin D seems not to increase the risk of the outcomes evaluated..." (2)

References:

1. NICE (January 2025). Maternal and child nutrition: nutrition and weight management in pregnancy, and nutrition in children up to 5 years)
2. Palacios C et al. Regimens of vitamin D supplementation for women during pregnancy. Cochrane Systematic Review October 2019.
3. NHS Specialist Pharmacy Service (December 2023). Using vitamin D during breastfeeding.