Low Vitamin D Levels Linked to Risk of Preterm Birth


Elham Reshid and Hailemariam Shimelis : Click for the PDF version

Vitamin D is a fat soluble vitamin, which is mainly obtained from sunlight. It is usually used for preventing and treating rickets, a disease that is caused by not having enough vitamin D (vitamin D deficiency). Sun light exposure is an easy and reliable way for most people to get vitamin D. Exposure to sunlight two to three times a week for about one-fourth of the time it would take to develop mild sunburn will make the skin to produce enough vitamin D.

Nevertheless, vitamin D deficiency is more common than it might be expected and is associated with different clinical conditions. For decades, vitamin D was known as a nutrient that was important only for bone health but over the past 10 to 15 years, scientists have learned that vita-min D has diverse functions in the body, including actions that may be important for maintaining a healthy pregnancy.

Gestational diabetes, severe preeclampsia, infertility and increased frequency of cesarean section have been known to result from deficiency of maternal vitamin D with the reason being the non-classic action of Vitamin D. Vitamin D receptor (VDR) and the 1-a-hydroxylase enzyme are expressed in a wide variety of tissues and this provided the biological plausibility behind the non-classical actions of vitamin D. A recent study suggests that women with the lowest level of vitamin D during pregnancy were about 1.5 times more likely to deliver early compared to those with the highest level.

The finding remained the same even after the researchers ac-counted for other factors linked to preterm birth, such as overweight, obesity, and smoking. Thus, according to the Institute of Medicine’s Food and Nutrition Board, pregnant women should get 600 international units (IUs) of vitamin D daily.

In this study, researchers looked at just over 2,100 women who didn’t give birth early, and more than 1,100 who delivered preterm. The researchers found that as the women’s blood levels of vitamin D decreased, the chance of preterm birth increased. Premature birth can lead to lifelong problems for a baby and can cause a number of problems, including in the lungs, brain, eyes, ears, and the digestive and immune systems as the investigators suggested.

However, according to one of the investigators, the study wasn’t designed to prove that low vitamin D levels actually caused the early deliveries and might not absolutely prove cause and effect relationship. Women should not also run out and start taking vitamin D supplements as well, unless they are recommended by their doctor to take prenatal vitamin, which includes vitamin D.

A systematic review research done to assess vitamin D supplement during pregnancy also supports the earlier statement. The evidence base is currently insufficient to support definite clinical recommendations regarding vitamin D supplementation in pregnancy. Point to take from these researches will be to have an adequate amount of vitamin D during pregnancy and advising pregnant women to be exposed to sunlight as it is the cheapest source to prevent the problem.






Barrett, A. McElduff.Vitamin D and pregnancy: An old problem revisited. Best Practice & Re-search Clinical Endocrinology & Metabolism 24 (2010) 527–539




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