Vitamin D status during pregnancy affects the child’s bone health even at age seven years

Vitamin D is important for calcium uptake and bone health. According to a placebo-controlled follow-up study published in the American Journal of Clinical Nutrition, children whose mothers supplemented with vitamin D during their pregnancy continue to have stronger bones, even at the age of seven years.
The pregnant women in the study took 25 micrograms of vitamin D, which is more than twice the officially recommended intake. It is generally important for the child’s health that its mother has optimal vitamin D levels in the blood during pregnancy and while breastfeeding.

An earlier study, the Maternal Vitamin D Osteoporosis Study (MAVIDOS), showed that vitamin D supplementation of pregnant women positively affected their offspring’s bone health and bone mineral density at the age of four years. This study looked at pregnant women from three hospitals in Great Britain (Southampton, Sheffield, and Oxford). The participants were split into two groups. One group was supplemented with 25 micrograms of vitamin D daily from week 14-17 of pregnancy until delivery, while the other group took placebo during the same period.
At age four, the children’s bone health and bone density were examined using scans and different measuring methods. It turned out that children whose mothers took vitamin D during their pregnancy had stronger and healthier bones based on the following parameters:

• BMC (Bone Mineral Content) that measures the bone mineral density
• BMD (Bone Mineral Density) that measures the calcium content
• BMAD (Bone Mineral Apparent Density) that is especially important when measuring bone density in children

In the current follow-up study, the scientists wanted to see if the protective effect of maternal vitamin D supplementation continued to benefit the children. A total of 447 children aged 6-7 years had their bone health assessed using the same parameters. The study showed that vitamin D supplementation during pregnancy continued to show a positive effect on bone health when compared to placebo. The researchers therefore concluded that vitamin D during pregnancy may be an important strategy for improving bone health and general health in the population.

Why is vitamin D so important for bone health and general health?

Vitamin D is important for the body’s uptake of calcium. Around 99 percent of all calcium is stored in our bones and teeth. During pregnancy, vitamin D plays an important role in the development of bones and teeth in the child. According to the above-mentioned studies, maternal vitamin D supplementation during pregnancy has a long-term impact on bone health that can be seen several years after the child has been born.
Most cells in the body have vitamin D receptors, and it is vital for the expecting mother to have a sufficient vitamin D status because this nutrient also plays a role in the development of the child’s nervous system, immune defense, and many other things.
Earlier research has demonstrated that vitamin D deficiency during pregnancy increases the risk of the child becoming overweight later in life or developing diseases like asthma, autism, and sclerosis.

Vitamin D recommendations for pregnant and breastfeeding women

The health authorities in Denmark recommend that pregnant and breastfeeding women take 10 micrograms of vitamin D all year round. This, however, is no guarantee of optimal blood levels that should ideally be above 75 nmol/L. As shown in the current review, the pregnant women got 25 micrograms. Vitamin D is lipid soluble, and it is recommended to take the nutrient in an oil matrix in gelatin capsules for better absorption.
According to the health authorities, the safe upper intake level for vitamin D supplementation is 100 micrograms (for adults, including pregnant and breastfeeding women).
The sun during the summer period is our major source of vitamin D. In the winter, however, the sun sits too low in the sky to enable vitamin D synthesis in the skin.

References

Rebecca j Moon et al. Pregnancy vitamin D supplementation and offspring bone mineral density in childhood follow-up of randomized controlled trial. The American Journal of Clinical Nutrition 2024

University of Southampton. Vitamin D during pregnancy boosts children´s bone health even at seven. ScienceDaily. 2024

Julia Sanguesa et al. Prenatal Vitamin D Levels Influence Growth and Body Composition until 11 Years in Boys. Nutrients 2023

Andrea L. Darling et al. Association between maternal vitamin status in pregnancy and neurodevelopmental outcomes in childhood: results from the Avon Longitudinal Study of Parents and Children. (ALSPAC) British Journal of Nutrition, 2017