Women taking daily vitamin D supplements during pregnancy had children with stronger bones, with benefits lasting into mid-childhood, a new study has found. The randomized controlled trial established a causal link, suggesting that vitamin D supplementation during pregnancy directly strengthens children’s bones. Vitamin D—the “sunshine vitamin”—is essential for bone health because it helps the body absorb calcium, which is needed to build strong bones and teeth.

The baby’s skeleton forms rapidly during pregnancy, and having enough vitamin D helps support this growth. Vitamin D “strengthens children’s bones and reduces the risk of conditions like osteoporosis and fractures in later life,” Moon said in the press release. The MAVIDOS study followed nearly 1,000 pregnant women, all receiving 1,000 IU of vitamin D daily between 11 and 14 weeks of pregnancy.

According to the results, vitamin D supplementation during pregnancy improved bone mineral density in children at age 4. The MAVIDOS team also demonstrated that vitamin D supplementation could alter gene activity, aiding specific genes that regulate growth and mineralization. This helps explain why children born to mothers who took vitamin D have better bone health.

While vitamin D can also be obtained through sun exposure, fatty fish, mushrooms, and certain fortified foods like milk and eggs, many pregnant women find it difficult to get enough vitamin D from diet and sunlight alone. “People think that if th.