Pregnant women taking prenatal supplements may not be getting enough vitamin D, shows a new Vancouver-based study led Timothy Green, associate professor at the University of British Columbia and Child & Family Research Institute scientist at BC Children’s Hospital.
Published today in the Canadian Journal of Public Health, the study found that while almost 80 per cent of pregnant women reported taking supplements containing vitamin D, many were vitamin D insufficient.
Insufficient means that blood levels of the specific vitamin are below national recommendations. The study of 336 women who were 20-35 weeks pregnant found that:
- 65 per cent of pregnant women have vitamin D levels lower than recommended by the Canadian Paediatric Society for pregnant and breastfeeding women.
- 24 per cent 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,” says Green, who teaches human nutrition at UBC’s Faculty of Land and Food Systems.
“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 and can lead to rickets. In addition, newborns with low levels of vitamin D may have increased risk of developing type 1 diabetes, asthma and low bone mass in later life. Low levels of vitamin D may also increase a woman’s risk of preeclampsia. Preeclampsia is the sudden onset of high blood pressure in pregnancy and the leading cause of maternal death in Canada.
Women were recruited for this study at BC Women’s Hospital & Health Centre, an agency of the Provincial Health Services Authority; Douglas College prenatal programs; and community health centres.
Participants gave a blood sample and completed a questionnaire on pre-pregnancy weight, age, smoking status, ethnicity, annual income, education and diet. The research found factors with the greatest impact on vitamin D levels included average sun exposure at the time of participation in the study, vitamin D intake from food and supplements, and skin colour.
“We can obtain vitamin D from the sun, but in our climate we see little sunlight five to seven months a year,” says Green. “There are few good natural sources of vitamin D and fortified foods do not contain enough vitamin D on their own.”
“That’s why research into supplements, how much pregnant women should be taking and how effective they are, is so important,” says Green, whose current research focuses on vitamin D intake in pregnant and breastfeeding women to determine how much of the vitamin women need to consume to meet national recommendations.
Studies led by Assoc. Prof. Green are currently recruiting for women 18-42 years of age who are 13-22 weeks pregnant. For more information, please contact Kaitlin March, 778.989,5984 or firstname.lastname@example.org.
This research was supported by UBC’s Faculty of Land and Food Systems and CFRI. Study collaborators include:
- Dr. Sheila Innis, scientist and director, Nutrition and Metabolism Research Program, CFRI; and professor, Division of Neonatology, UBC Department of Pediatrics
- Dr. Peter von Dadelszen, senior clinician scientist and co-director of the Reproduction and Healthy Pregnancy Cluster, CFRI; consultant, Maternal Fetal Medicine at BC Women’s Hospital & Health Centre and professor, UBC Dept. of Obstetrics and Gynecology
CFRI conducts discovery, clinical and applied research to benefit the health of children and families. It is the largest institute of its kind in Western Canada. CFRI works in close partnership with UBC; BC Children’s Hospital and Sunny Hill Health Centre for Children, BC Women’s Hospital & Health Centre, agencies of PHSA; and BC Children’s Hospital Foundation. CFRI has additional important relationships with British Columbia’s five regional health authorities and with B.C. academic institutions Simon Fraser University, the University of Victoria, the University of Northern British Columbia, and the British Columbia Institute of Technology. For more information, visit www.cfri.ca.
BC Children’s Hospital, an agency of the Provincial Health Services Authority, provides expert care for the province’s most seriously ill or injured children, including newborns and adolescents. BC Children’s is an academic health centre affiliated with the University of British Columbia, Simon Fraser University, and the Child & Family Research Institute. For more information, please visit www.bcchildrens.ca.