Pregnancy vitamin D supplementation boosts bone density in kids up to age 7

By Dr. Chinta SidharthanReviewed by Lily Ramsey, LLMNov 8 2024

Study suggests maternal vitamin D intake during pregnancy may improve long-term bone health and lean mass in children.

Study: Pregnancy vitamin D supplementation and offspring bone mineral density in childhood follow-up of a randomized controlled trial. Image Credit: Nemer-T/Shutterstock.com

In a recent study published in The American Journal of Clinical Nutrition, a team of scientists from the United Kingdom (U.K.) investigated the effects of vitamin D supplementation during pregnancy on the bone density of children aged 6 to 7.

The study aimed to understand whether vitamin D intake by expectant mothers could positively influence the offspring’s bone health and gain insights into potential public health strategies for improving long-term skeletal development.

Background

Vitamin D is essential for bone health and plays a key role in calcium balance and skeletal growth. Especially during the fetal and early postnatal periods, vitamin D levels have been linked to skeletal development, suggesting that maternal vitamin D status could impact the infant’s future bone density and overall bone strength.

Observational studies have found that higher maternal vitamin D levels during pregnancy are associated with greater bone mineral density (BMD) and bone mineral content (BMC) in children at various ages, including at birth and in early childhood.

However, the findings are inconsistent about the duration of the benefits and the supplementation dosages, and whether these benefits persist or decrease through childhood requires further examination.

About the study

In the present study, the researchers conducted an exploratory, posthoc analysis of the Maternal Vitamin D Osteoporosis Study (MAVIDOS trial) to examine whether gestational vitamin D supplementation continued to have a positive effect on the child’s BMD at ages 6 to 7.

The MAVIDOS trial was a randomized, double-blind, controlled study that evaluated the effect of vitamin D supplementation during pregnancy on children’s bone density at age 4.

Pregnant participants, screened at three U.K. hospitals and within 14 weeks of gestation, were recruited if they were over 18, carrying a single fetus, and had blood vitamin D levels between 25 and 100 nanomoles per liter.

In the trial, the participants were randomly assigned to receive either 1,000 international units (IU) of cholecalciferol (vitamin D3) or a placebo from around 14 weeks of gestation until delivery. The participants did not know which group they were assigned to, but all participants were provided with standard antenatal care.

After birth, detailed records of gestational age, birth weight, and breastfeeding duration were collected, and follow-ups were conducted at ages 4 and 6 to 7 years.

Additionally, the children's weight, height, and physical activity levels were assessed at each follow-up, and dual-energy X-ray absorptiometry scans were conducted to measure bone area, bone mineral apparent density (BMAD), BMD, and BMC for the lumbar spine and the whole body.

These scans allowed the researchers to derive detailed bone metrics while correcting for variables like child age, height, and weight.

Statistical analyses consisted of linear regression to compare the bone density outcomes between the vitamin D and placebo groups while adjusting for potential confounders such as breastfeeding duration, additional vitamin D use, and physical activity. The researchers also assessed if the effects varied based on the gender of the child.

Results

The study found that maternal vitamin D supplementation led to higher BMD and BMAS in children at ages 6 to 7 as compared to supplementation with a placebo.

Children of mothers who took vitamin D supplements during pregnancy showed a 0.18 standard deviation increase in whole-body BMD and a similar increase in BMAD, while lean mass was also found to be slightly higher. These effects appeared stable over time, as the positive differences were seen to be constant at age 4 and ages 6 and 7.

Additionally, the children in the supplemented group demonstrated higher mineral content in their bones and higher BMD in the lumbar spine regions.

The measurements for the whole body were more consistent over time, suggesting a lasting benefit of prenatal vitamin D supplementation on general skeletal growth.

In the lumbar spine scans, a constant positive effect was noted in BMD and BMAD, while the bone area and BMC effects were stronger at age 4 and tapered by ages 6 and 7.

The supplementation group also showed increased lean mass, suggesting that prenatal vitamin D supplementation had beneficial effects on body composition and bone structure. There was no significant difference in effects based on the child’s gender or maternal baseline vitamin D levels.

Conclusions

The results suggested that prenatal vitamin D supplementation provided long-term bone health benefits to the children without any evident adverse effects.

The researchers believe that additional studies are required to determine whether the beneficial effects continue into adulthood. These insights could help formulate population-level health strategies for improving bone health.