What is the role of Vitamin D (Cholecalciferol) supplementation during pregnancy?

From the Guidelines

Vitamin D supplementation during pregnancy is recommended to maintain a concentration of 50 nmol/L or greater with a serum PTH within normal limits. The standard dose is >40 mcg (1000 IU) of vitamin D daily, as recommended by the most recent and highest quality study 1. Women with vitamin D deficiency or high risk factors may need higher doses, as prescribed by their healthcare provider. Supplementation should begin early in pregnancy and continue throughout. Vitamin D is crucial during pregnancy because it helps with calcium absorption for fetal bone development, supports immune function, and may reduce the risk of pregnancy complications like preeclampsia and gestational diabetes. Some key points to consider:

• The body can produce vitamin D through sun exposure, but many pregnant women don't get enough from sunlight and diet alone.
• Before starting any supplement beyond what's in a prenatal vitamin, pregnant women should consult with their healthcare provider who may check vitamin D levels through a blood test to determine the appropriate dosage.
• Calcium should be added to ongoing vitamin D supplementation as needed to maintain PTH within normal limits 1.
• It is essential to monitor serum levels of many micronutrients and macronutrients during pregnancy, including serum vitamin D with calcium, phosphate, magnesium, and PTH, at least once per trimester and use pregnancy-specific ranges 1.

From the Research

Vitamin D Supplementation During Pregnancy

• Vitamin D supplementation during pregnancy may be needed to protect against adverse pregnancy outcomes, such as pre-eclampsia, gestational diabetes, and low birthweight 2, 3, 4, 5, 6
• The evidence suggests that supplementing pregnant women with vitamin D alone probably reduces the risk of pre-eclampsia, gestational diabetes, and low birthweight, and may reduce the risk of severe postpartum haemorrhage 2, 4, 6
• However, the evidence is uncertain about the effect of vitamin D supplementation on preterm birth, with some studies suggesting a reduction in risk and others suggesting no effect or an increased risk 2, 3, 4, 6
• The combination of vitamin D and calcium may reduce the risk of pre-eclampsia, but may also increase the risk of preterm birth 2, 4
• The optimal dose of vitamin D supplementation during pregnancy is unclear, with some studies suggesting that higher doses (1000-4000 IU/day) may be more effective than lower doses (600 IU/day) 3, 5
• The evidence is generally of low to moderate certainty, and further rigorous, high-quality, and larger randomized trials are required to evaluate the effects of vitamin D supplementation in pregnancy, particularly in relation to the risk of maternal adverse events 2, 3, 4, 6

Key Findings

• Vitamin D supplementation during pregnancy may improve maternal and neonatal health outcomes 2, 3, 4, 5, 6
• The evidence suggests that vitamin D supplementation may reduce the risk of pre-eclampsia, gestational diabetes, and low birthweight 2, 4, 6
• However, the evidence is uncertain about the effect of vitamin D supplementation on preterm birth and other outcomes 2, 3, 4, 6
• Further research is needed to determine the optimal dose and duration of vitamin D supplementation during pregnancy, as well as its effects on maternal and neonatal health outcomes 2, 3, 4, 6

Implications for Practice

• Pregnant women should be advised to take vitamin D supplements to reduce the risk of adverse pregnancy outcomes, such as pre-eclampsia and low birthweight 2, 4, 5, 6
• The optimal dose of vitamin D supplementation during pregnancy is unclear, and further research is needed to determine the most effective dose 3, 5
• Healthcare providers should be aware of the potential benefits and uncertainties of vitamin D supplementation during pregnancy and discuss these with their patients 2, 3, 4, 6