Vitamin D is essential for maintaining healthy bones, and a recent study reveals that supplementing with this vitamin during pregnancy can have a lasting impact on children's bone health, keeping them strong into mid-childhood.

Researchers found that children have greater bone mineral density at age 7 when expectant mothers had taken vitamin D supplements during pregnancy.

"Our findings show that the benefits of vitamin D supplementation during pregnancy persist into mid-childhood. This early intervention represents an important public health strategy. It strengthens children's bones and reduces the risk of conditions like osteoporosis and fractures in later life," said Dr. Rebecca Moon, lead investigator of the study in a news release.

The researchers began the MAVIDOS study in 2009, enlisting over 1,000 pregnant women in England to explore the potential effects of vitamin D on child bone health. During the trial, the women were randomly divided into two groups: one received an additional 1,000 International Units of vitamin D daily, while the other took a placebo. The participants and healthcare providers who attended them did not know which group they belonged to.

As part of the study's first phase, researchers assessed the bone mass of the children at age four using detailed bone scans. The results showed that children born to mothers who received vitamin D supplements during pregnancy had greater bone mass compared to those whose mothers had taken a placebo.

In the latest phase of the study, researchers examined whether the benefits of prenatal vitamin D would extend into mid-childhood. They conducted follow-up bone scans on 454 children between the ages of six and seven, finding that those whose mothers had received vitamin D supplements continued to show stronger bone density at age seven.

"These findings suggest that pregnancy vitamin D supplementation may represent a population health strategy to improve bone health, although further work is needed to demonstrate the persistence of this effect into adulthood, together with, ideally replication in additional studies," the researchers wrote in the study published in The American Journal of Clinical Nutrition.

Although vitamin D deficiency during pregnancy remains a significant concern, the U.S. dietary recommendations for vitamin D intake in pregnant women remain conservative. It is primarily due to concerns over potential toxicity. However, current evidence suggests that a daily intake of 4,000 IU of vitamin D3 is both safe and necessary to meet the needs of all pregnant women, with no adverse effects reported.

Since the effects and harms of vitamin D supplementation on maternal and infant health are not yet fully understood, WHO does not recommend vitamin D supplementation as part of standard prenatal care.

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