Researchers in the United States have found an association between vitamin D levels in pregnant women and the risk of pre-eclampsia; they say women who have a vitamin D deficiency early in their pregnancy are at risk from pre-eclampsia.
Pregnant women who have pre-eclampsia, which is also known as toxemia, suffer from raised blood pressure as well as swelling of the hands and feet and it is the most common cause of premature birth, and is a factor in 76,000 deaths each year worldwide.
In a study by Dr. Lisa M. Bodnar, an assistant professor of epidemiology at the University of Pittsburgh Graduate School of Public Health, data and blood samples were evaluated from 1,198 women and newborns from 1997 and 2001 at Magee-Womens Hospital.
Blood samples were collected from the pregnant women prior to 22 weeks pregnancy and again just before delivery and newborn umbilical cord blood also was tested for 25 hydroxyvitamin D, an indicator of vitamin D levels in the babies.
The researchers found that the risk of pre-eclampsia could be five times as high as that for those who were not deficient of vitamin D during pregnancy and even a small decline in vitamin D concentration more than doubled the risk of pre-eclampsia.
The researchers were concerned that many of the women had apparently been taking prenatal vitamins, which typically contain 200 to 400 International Units (IU) of vitamin D.
A deficiency in vitamin D has been linked to rickets, osteoporosis asthma and schizophrenia, as well as tuberculosis, cancer, periodontal disease, multiple sclerosis, chronic pain, depression, seasonal affective disorder and several autoimmune diseases.
The research team say the results showed that maternal vitamin D deficiency early in pregnancy is a strong, independent risk factor for pre-eclampsia.
Vitamin D is only present in a few foods such as oily fish and eggs but certain foods are fortified with the vitamin; however many believe that the fortified vitamin, which is usually vitamin D2, is inferior to vitamin D3.
Vitamin D3 is produced in skin exposed to sunlight and pregnant and breastfeeding women are advised to take 200 IU, but experts suggest more is needed as the vitamin is safe and provides many health benefits.
The study is published in the Journal of Clinical Endocrinology and Metabolism.