Pregnant women should take vitamin D supplements

Pregnant women should take vitamin D supplementsIt is important for the health of the unborn child that the expecting mother keeps her vitamin D levels high during her entire pregnancy. According to a study from Southampton University, vitamin D supplementation is less effective, if a pregnant woman starts with low levels of vitamin D in the early stage of her pregnancy, has major and sudden weight gain, and gives birth during winter.

The study revealed that pregnant women react differently to vitamin D supplementation, which is why one should adjust supplementation to individual needs. All the body’s cells have vitamin D receptors that are important for calcium uptake, the bones, the muscles, the brain, the nervous system, and the immune system. Vitamin D is considered a hormone and believed to control around 5-10 percent of our genes. The summer sun is our primary vitamin D source, while our food only makes a minor contribution that is below the reference intake (RI). Our modern lifestyle with many indoor activities, our use of sunscreens, plus having dark skin, being old, being overweight, and having type-2 diabetes explains why many people have too little vitamin D in their blood.

Lack of vitamin D increases the child’s risk of weak bones and serious diseases

Lack of vitamin D during pregnancy is not only likely to damage the mother’s health but may even have a long-term impact on the development and health of the child. For instance, a vitamin D deficiency during pregnancy can increase the child’s risk of developing weak bones, autism, and sclerosis later in life.
Nicolas Harvey, a professor from the University of Southampton, headed the above-mentioned study and underlines how important it is for the child’s health that the mother has enough vitamin D in her blood. According to the study, the expecting mother’s blood levels of vitamin D should be optimized with respect to individual factors such as pregnancy term and body weight.

Strategy for improving the health of future generations

800 pregnant women participated in the described double-blind, placebo-controlled study, MAVIDOS (Maternal Vitamin D Osteoporosis Study). Half the participants got a daily supplement with 25 micrograms of vitamin D, while the other half got matching placebo (dummy pills) beginning from the 14th week of pregnancy and continuing until birth. Analyses showed that those women who got vitamin D supplements had different levels of the nutrient in their blood, even though they were given the same dosage. Based on this finding, the researchers noted that the women who gave birth during summer, who had the smallest weight gain during their pregnancy, and who had the highest vitamin D levels at the beginning of their pregnancy, tended to have higher levels of the nutrient later on in their pregnancy. Women who constantly took vitamin D also had higher blood levels of the nutrient than those who did not take supplements.
As shown, pregnant women react differently to vitamin D supplementation. According to Professor Cyrus Cooper from the University of Southampton, the study serves to show that vitamin D supplementation should be adjusted to the season, to weight increase, and to other individual needs. This entirely new and rather simple strategy may improve the health of the pregnant woman and perhaps even the health of future generations.

Vitamin D recommendations differ widely

In Denmark, the reference intake (RI) for vitamin D is 10 micrograms from the age of 11 years and upward. Since July 2016, the British health authorities have recommended everyone from the age of one year onward to take a daily 10 microgram supplement of vitamin D – especially during the winter period.
The pregnant participants in the before mentioned Southampton study got 25 micrograms of vitamin D daily, which is more than double the amount that is recommended to pregnant women in Denmark.

Measuring vitamin D in the blood

Vitamin D in the blood is measured as 25-hydroxyvitamin. The official threshold values are 50 ng/ml, but leading experts claim that this level is inadequate and suggest 75-100 ng/ml for optimal disease prevention.


Rebecca J. Moon et al. Determinants of the Maternal 25-Hydroxyvitamin D Response to Vitamin D Supplementation During Pregnancy. The Journal of Clinical Endocrinology & metabolism. 2016

Khaled Sall et al. Randomized controlled trial of vitamin D supplementation in children with autism spectrum disorder. Journal of Child Psychology and Psychiatry. 2016

John J Cannell. Autism Causes, Prevention and Treatment: Vitamin D Deficiency and the Explosive Rise in Autism Spectrum Disorder. Sunrise River Press. 2015

Alberto Ascherio, MD, DrPH et al. Vitamin D Status During Pregnancy and Risk of Multiple Sclerosis in Offspring at Women in the Finnish Maternity Cohort. JAMA Neurol. March 2016

Benjamin M Greenberg, MD, MHS. Vitamin D During Pregnancy and Multiple Sclerosis: An Evolving Association. JAMA Neurol. March 2016