All pregnant women should take a 10 microgram (400 IU) vitamin D supplement every day. This will give the baby enough vitamin D for the first few months of life. To optimize vitamin D health, it is suggested to support the production of 1,25 (OH) 2D by overcoming the “substrate limitation”. Although there is general consensus on the need to take vitamin D supplements during pregnancy, there is confusion as to the ideal levels and the dose required to achieve them.
Serum alkaline phosphate, a substitute marker for vitamin D deficiency, cannot be used as such during pregnancy, due to the placental secretion of this enzyme. For 75% of the population that is lactose intolerant, fortified dairy products are not a reliable source of vitamin D consumption. Several authors describe the relationship between low levels of vitamin D and several elements of metabolic syndrome. The study, published in the Journal of Public Health, analyzed the results of the MAVIDOS trial, a multicenter, double-blind, randomized, placebo-controlled trial of vitamin D supplementation during pregnancy.
When talking about the dose of vitamin D during pregnancy, we must remember the extremely low levels of vitamin D seen in South Asian women. The average prenatal vitamin only contains 400 IU of vitamin D, so additional supplements should be taken every day. A study evaluating bone mass at 9 years of age found a positive correlation with a high level of vitamin D in the mother, while another analysis of the same longitudinal study could not detect any relevant association. In healthy, asymptomatic prenatal women, between 1,000 and 2000 IU can be supplemented daily during the second and third trimesters, without fear of vitamin D toxicity or teratogenicity.
These studies have not been included in the most recent Cochrane review (2001) on the administration of vitamin D supplements to women during pregnancy. The analyses showed that 65.6% of women who took additional vitamin D had a spontaneous vaginal delivery, or “natural” birth, compared to 57.9% in the placebo group. It's not known exactly how long it takes to be in the sun to produce enough vitamin D to meet the body's needs. Vitamin D, also known as the “sunshine vitamin”, provides many health benefits; it promotes bone health, boosts immunity, and even helps prevent some forms of depression.
If you don't take a vitamin D supplement during pregnancy, there's a risk that your child will have soft bones. With the available evidence on vitamin D supplementation and the conflicting interpretations of everything that has been published, it is difficult to issue evidence-based guidelines.
