By Bonnie James/Deputy News Editor
A Qatar study has proved that low vitamin D level is common in pregnant women in Qatar and routine oral supplementation with 50,000 International Units (IU) a week resulted in improvement.
The “Vitamin D study in pregnant women and their babies”, conducted by Hamad Medical Corporation’s Samar al-Emadi and Dr Mohamed Hammoudeh (division head, Rheumatology Medicine Department), has been published a few days ago in Qatar Medical Journal, hosted on qscience.com
Weekly doses of 50,000 IU vitamin D during pregnancy resulted in acceptable vitamin D level and the newborn’s vitamin D level correlated with the mother’s levels.
At the present, vitamin D supplementation is not part of antenatal care programme in Qatar, the authors of the study pointed out.
Vitamin D deficiency during pregnancy is a worldwide epidemic, with different studies reporting a prevalence ranging from 18 - 84% depending on the country of residence and clothing customs.
The importance of vitamin D for foetal and infant skeletal development has long been recognised. Several studies have reported association between infant size and vitamin D status.
Vitamin D is important for multiple physiologic processes, including calcium absorption. In recent years there has been an increased understanding of the role that vitamin D plays in regulation of cell growth, immunity, and cell metabolism, as pointed out in the study report.
Vitamin D receptors can be found in most tissues and cells in the body, and the impact of a vitamin D deficiency on the developing foetus and maternal health is of significant concern.
The current recommendation for vitamin D intake during pregnancy of 200 - 400 IU has little scientific support and has been recently challenged.
The recommended dose of vitamin D during pregnancy differs in different parts of the world. If it is 200 IU/day in the US, Australia, New Zealand and Canada, the daily recommended dose in the UK is 400 IU/day.
Historically, vitamin D supplementation during pregnancy was thought to be a risk factor for supravalvular stenosis (a heart defect that develops before birth) in infants, which was based on a 1964 case report.
Different studies suggested that the daily use 1,000IU, 2,000 IU, 4,000 IU, and 6,400 IU would help to eliminate vitamin D insufficiency without apparent toxicity in pregnant women and their infants.
The concern of using higher doses of vitamin D might cause hypercalcemia (elevated calcium level in the blood), elevated calcium in the urine, kidney stone and soft tissue and vascular calcification toxicity is likely to worsen with calcium supplementation.
“Hypercalcemia, the most worrying toxicity, occurs with vitamin D levels of more than 80 or 100 ng/ml, and in our study no one reached this level through out pregnancy and in newborns with normal levels of calcium in spite of supplementation,” the authors said.
The highest dose of vitamin D studied during pregnancy was given to 15 hypoparathyroid (decreased function of the parathyroid glands) women who received 100,000 IU/day in order to maintain serum calcium. No adverse effects were observed in these mothers or their infants.
Conducted at HMC’s outpatient unit and delivery room, the study covered 97 pregnant women, who were recruited in their first trimester between December 2007 and March 2010.
Weekly oral vitamin D (50,000 IU) were prescribed after an initial testing for serum level of 25-hydroxyvitamin D, parathyroid hormone, calcium, phosphorus, total protein and albumin.
Other multivitamins supplementations were allowed during pregnancy. The same tests were repeated at each trimester. Umbilical cords vitamin D levels were determined at birth.
Out of the respondents, eight dropped out from the study for several reasons, and 19 patients had pregnancy loss. Data were available for 97 women in the first trimester, 78 women in the second trimester and 61 women in the third trimester.
There were no toxic levels of vitamin D in any of the women at the second or third trimesters or in the newborns. The mean levels of vitamin D in the second and third trimester were not significantly different in those women who were taking multivitamin supplementation and those who were not.