Study leader Dr. Timothy Green, a scientist at the Child & Family Research Institute and an associate professor at the University of British Columbia, found that while almost 80 percent of pregnant women reported taking supplements containing vitamin D, many were vitamin D insufficient.
Insufficient means blood levels of the specific vitamin are below national recommendations.
The study of 336 women who were 20 to 35 weeks pregnant found:
-- 65 percent of pregnant women have vitamin D levels lower than recommended by the Canadian Pediatric Society for pregnant and breastfeeding women.
-- 24 percent of pregnant women have vitamin D levels lower than recommended by Health Canada for women of all ages including those who are pregnant and breastfeeding.
"We know vitamin D is vital to the health of women and their babies, but there is currently little consensus on how much vitamin D pregnant women need for optimum health." Green says in a statement. "This research shows that, regardless of the recommendation you use, a significant number of women are not getting enough vitamin D."
Vitamin D is essential for bone growth and development in the fetus. Low levels of vitamin D at birth have been associated with lower birth weight, rickets and increased risk of developing type 1 diabetes, asthma and low bone mass in later life, Green says.
The findings are published in the Canadian Journal of Public Health.