Vitamin D in Pregnancy Vital for Moms and Babies

Embarking on the journey toward motherhood can be one of the most exciting times of a woman’s life.

Today, we know the importance of a good prenatal multivitamin and its vital role in providing iron to support increased blood volume and the growth of a whole new organ, the placenta. Calcium helps the baby’s developing skeleton, and a high-quality multivitamin should have 400 milligrams of folate to prevent neural tube defects like spina bifida.

But most people don’t realize the importance of having optimal vitamin D levels before, during and after pregnancy. In fact, researchers at the University of Calgary have found that pregnant women in Alberta do not get enough vitamin D.

Some of the best work in this area has been done by Drs. Carole Wagner and Bruce Hollis at the Medical University of South Carolina (MUSC).

Their research on the benefits of vitamin D during pregnancy was so convincing that their hospitals (five in all) added vitamin D supplements to the prenatal care programs. All women delivering babies at MUSC now get 5,000 international units of vitamin D daily, 10 times higher than what Health Canada recommends — more than you could get from food alone.

While sunshine easily produces twice this amount in only 15 minutes during the summer, supplementation is needed during the winter because the sun is at the wrong angle to make vitamin D.

As well, they’ve studied the role of vitamin D supplementation during lacta­tion — the only supplement recommended from birth. That’s because most women’s vitamin D levels are too low to produce vitamin D in breastmilk. All other vitamins present in breastmilk are at levels that support infant growth.

Wagner and Hollis found that if the mother takes enough vitamin D it enters the breastmilk at levels comparable to giving vitamin D directly to the baby. However, mom needs to take around 6,000 IU per day to reach these levels.

Pure North encourages our pregnant participants to get enough vitamin D to reach blood levels above 100 nmol/L — and we measure to ensure they do!

Vitamin D Benefits During Pregnancy

Better for Baby

Optimal vitamin D levels can prevent preterm births by up to 60 per cent. Without vitamin D supplements, babies can develop vitamin D deficiency rickets, a skeletal disorder.

Better for Mom

Optimal vitamin D levels lower the risk of pre-eclampsia, a condition in which pregnant women develop high blood pressure, rapid weight gain and swelling of the hands and face.

Preeclampsia can lead to health problems for both mom and baby.

Fortifying the Future

Besides having a better chance for healthy bone development in the womb, children who have received optimal vitamin D have a lower risk of Type 1 diabetes and asthma as young children.


McDonnell SL, et al. Maternal 25(OH)D concentrations ≥40ng/mL associated with 60% lower preterm birth risk among general obstetrical patients at an urban medical centre.
PLoS One. 2017;12(7):e0180483.

Hollis BW, Wagner CL, et al. Maternal Versus Infant Vitamin D Supplementation During Lactation: A Randomized Controlled Trial. Pediatrics. 2015 Oct;136(4):625-34.

Litonjua AA, et al. Effect of prenatal supplementation with vitamin D on asthma or recurrent wheezing in offspring by age 3 years. JAMA 2016;315(4):362-70.