Many pregnant people take vitamins to ensure the health of their unborn babies, but the benefits of at least one of those vitamins for children extend beyond birth and into elementary school.

The decade-old Maternal Gestational Vitamin D Osteoporosis Study, or MAVIDOS trial, found that taking vitamin D supplements during pregnancy improves the bone health of their newborns.

A recent follow-up of the original trial shows that the benefits of prenatal vitamin D last much longer. It appears they last at least until the child's seventh year.

The original MAVIDOS was a randomized double-blind, placebo-controlled trial that assessed the effect of vitamin D supplementation during pregnancy. The study was conducted at three UK hospitals and involved women who were there for early pregnancy ultrasound screenings.

Children whose mothers took vitamin D supplements during pregnancy had healthier bones. In particular, they had increased bone health in their lumbar spines.

A total of 965 pregnant people were included in the study, and all were between 11 and 14 weeks of pregnancy when they began receiving 1,000 IU of vitamin D daily until they delivered. Seven hundred and twenty-three children were delivered at term. Of these, 477 received a DEXA scan at four years of age.

A DEXA scan, or dual-energy X-ray absorptiometry scan, is a painless, low-dose X-ray that measures bone density, or the thickness and strength of bones. The scan uses two X-ray beams to pass through the body, usually the spine and hips, to measure the amount of calcium and other minerals in the bones.

In this study, 447 of the children were given a DEXA scan at the age of seven. The results revealed that even after the researchers adjusted for sex, height, weight and the duration of breast milk consumption, those children whose mothers took vitamin D supplements during pregnancy had healthier bones. In particular, it showed that the kids had increased bone health in their lumbar spines.

The finding reaffirms the positive effects associated with vitamin D supplements during pregnancy, as well as demonstrating that the benefits persist beyond four years of age and into later childhood.

Better bone mineral density (BMD) is expected to help reduce fracture risk in these kids, though further studies are needed to see just how long the benefits of vitamin D last. Will the increase in bone mineral content (BMC) and bone mineral density persist as the children grow into adulthood? If so, it could mean that a future of fragile bones and the risk of fracture will significantly decrease.

Of course, kids can break bones even if those bones are strong, but there are things you can do to reduce the risk. The American Academy of Pediatrics (AAP) recommends five ways to help prevent the kinds of accidents that can cause fractures, including:

  • Physical activity: Weight-bearing exercise is encouraged to help improve bone health. Activities that involve jumping, like gymnastics or jumping rope, are particularly effective. However, too much mechanical loading without adequate nutrition or hormones can lead to stress injuries or fractures.
  • Nutrition: The AAP recommends that children and adolescents get the recommended amount of vitamin D and calcium. The most common sources of calcium are milk and other dairy products.
  • Safety equipment: Children should wear helmets, protective pads and seatbelts.
  • Teach children how to fall: Falling on the forearms and rolling can help reduce the risk of a broken bone.
  • Supervision: Keep an eye and ear on children and keep stairways clear of tripping hazards.

The study is published in the American Journal of Clinical Nutrition.