Vitamin D deficiency and insufficiency are common across the globe. Large epidemiological studies reveal the high prevalence of vitamin D in women, including antenatal and lactating mothers.
Vitamin D requirements are probably greater in pregnancy, as evidenced by physiologically higher 1,25-dehydroxy vitamin D levels seen in the second and third trimesters. While 1,25(OH) 2D levels do not correlate directly with 25 hydroxyvitamin D concentrations, the physiological rise in the active metabolite, the enhanced intestinal calcium absorption, and enhanced fetal requirement of calcium (250 mg/day in the third trimester) all point to the importance of vitamin D biology in pregnancy
The following people are more prone to Vitamin-D deficiency :
- infants and children aged under 4
- pregnant and breastfeeding women, particularly teenagers and young women
- people over 65
- people who have low or no exposure to the sun, for example, those who cover their skin for cultural reasons, who are housebound or confined indoors for long periods
- people with darker skin, for example, people of African, African-Caribbean or South Asian family origin.
- Suitable supplements should also be available for people with particular dietary needs (for example, people who avoid nuts, are vegan or have a halal or kosher diet)
Vitamin D Deficiency in Pregnancy
Studies are available to support the need for, and benefits of, vitamin D supplementation in pregnancy.The relationship between low vitamin D and adverse maternal outcomes such as pregnancy-induced hypertension, high blood pressure in diabetic pregnancy, gestational diabetes mellitus, recurrent pregnancy loss, preterm delivery, primary Caesarian section, and postpartum depression has been documented in recent years.
Evidence has also accumulated regarding the impact of maternal vitamin D levels on long-term health of offspring
Vitamin D Supplementation
Three categories of vitamin D supplementation are recommended.
- In general, vitamin D 10 micrograms (400 units) a day is recommended for all pregnant women in accord with the RCOG Guidelines. This
- High-risk women are advised to take at least 1000 units a day (women with increased skin pigmentation, reduced exposure to sunlight, or those who are socially excluded or obese). Women at high risk of pre-eclampsia are advised to take at least 800 units a day combined with calcium.
- Treatment. For the majority of women who are deficient in vitamin D, treatment for 4–6 weeks, either with cholecalciferol 20 000 iu a week or ergocalciferol 10 000 iu twice a week, followed by standard supplementation, is appropriate. For women who require short-term repletion, 20 000 iu weekly appears to be an effective and safe treatment of vitamin D deficiency. A daily dose is likely to be appropriate to maintain subsequent repletion (1000 iu daily).
Conclusion
Treatment of vitamin D deficient women and vitamin D supplementation is safe and is recommended for all women who are pregnant or breastfeeding. Low vitamin D concentrations are present in a significant proportion of the population. Women with pigmented or covered skin, obesity and immobility are at a higher risk. Low vitamin D concentrations have been associated with a wide range of adverse maternal and offspring health outcomes in observational epidemiological studies. However, despite a dearth of interventional evidence supporting supplementation/treatment of vitamin D in randomised controlled trial settings, it is generally accepted that supplementation/treatment is not harmful and may have some significant short- and long-term health benefits.
Specialist Obstetrics and Gynaecology
Aster Clinic, Dubai Silicon Oasis
