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Vitamin D deficiency in pregnancy highlighted

Many pregnant women are not getting enough Vitamin D even when they take supplements. The finding has been made as a result of research carried out by the Northern Ireland Centre for Food and Health (NICHE), which involves researchers from Queen's University Belfast.
Dr Valerie Holmes from Queen's School of Nursing and Midwifery co-authored the study which was published in the latest edition of the British Journal of Nutrition. The study was the first of its kind measuring the vitamin D status of pregnant women in Northern Ireland.

The Food Standards Agency recommends that all pregnant women take a daily dose of 10 micrograms of the vitamin. Deficiencies have been linked to rickets and lower bone density in children.

Although the main source of Vitamin D is synthesis following exposure to sunlight, it is also found in oily fish, eggs and in fortified foods including margarine and breakfast cereals and can also be taken as a food supplement. The group studied 99 expectant mothers living in Northern Ireland and tested them at three separate times during their pregnancy.

Testing at 12 and 20 weeks of pregnancy revealed that as many as 96% of the women had insufficient levels of vitamin D in their blood. Examination also revealed that at these test points, 35% could be classified as vitamin D deficient at 12 weeks and 44% at 20 weeks. During the third trimester, at 35 weeks, 75% had insufficient levels of the vitamin and 16% of women were deficient.

Dr Holmes, from the Nursing and Midwifery Research Unit, said: “While studies in other countries have reported low levels of vitamin D in pregnancy, the high percentage of women in this study who had insufficient levels is remarkable.

“Northern Ireland's northern latitude means that we are ‘in the dark' in terms of sunshine, and makes the issue of adequate vitamin D dietary intake even more important.

“While vitamin D status was improved in women who reported taking multivitamin supplements, many still had insufficient levels, suggesting that the amount present in multivitamins formulated for pregnancy may be too low to maintain adequate levels.

“Stores of vitamin D in the newborn baby depend on the mother's levels during pregnancy and where deficiency is severe there is an increased risk of rickets.  Previous studies have reported a link between low levels of vitamin D in pregnancy and lower bone density in children.”

Dr Holmes said further research was needed to determine exactly how much vitamin D women need to take to maintain adequate levels during pregnancy. She added that if pregnant women have any concerns about their nutrition they should consult their midwife or GP.

The research was carried out in collaboration with the University of Ulster and Belfast City Hospital.

Queen's University Belfast