Vitamin D During Pregnancy Promotes Bone Health in Children Even at the Age of Seven

According to a new study by the University of Southampton and University Hospital Southampton (UHS), children whose mothers took extra vitamin D during pregnancy also have stronger bones at the age of seven. Bone density measurements showed that these children have higher bone mineral density. Their bones contain more calcium and other minerals, making them stronger and less prone to fractures. The researchers say the findings underscore the importance of vitamin D supplementation during pregnancy as a public health strategy.

The Positive Effects of Vitamin D on Bone Health in Childhood

Dr. Rebecca Moon, NIHR Clinical Research Fellow in Child Health at the University of Southampton, led the analysis. She said: “Our findings show that the benefits of vitamin D supplementation during pregnancy last into mid-childhood. “This early intervention is an important public health strategy. It strengthens children’s bones and reduces the risk of conditions such as osteoporosis and fractures later in life.” Vitamin D regulates the levels of calcium and phosphate in the body – minerals that are essential for healthy bones, teeth, and muscles. In 2009, researchers launched the MAVIDOS study, recruiting over 1,000 women from Southampton, Oxford, and Sheffield. During their pregnancies, the women were randomly divided into two groups: one group took an additional 1,000 international units of vitamin D daily. The other group took a placebo tablet daily. Neither the pregnant women nor the doctors and midwives caring for them knew which group they belonged to.

Previous studies had examined the bone health of children at the age of four and showed that the bone mass of children whose mothers had taken vitamin D supplements during pregnancy was greater than that of children whose mothers had not taken vitamin D supplements. In this study, published in the American Journal of Clinical Nutrition, the researchers investigated whether the effects on bone health persisted into mid-childhood. The team observed 454 children aged six to seven years. These children were all born to mothers who had participated in the Southampton study. The results confirmed that the positive effect on the children’s bones was similar at ages four and six to seven.

Pregnant women in the UK are now routinely advised to take vitamin D supplements. The Southampton research team is part of the MRC Lifecourse Epidemiology Centre (MRC LEC) and the NIHR Southampton Biomedical Research Centre (BRC). The MAVIDOS study has helped researchers in Southampton understand possible mechanisms linking maternal intake of vitamin D supplements and children’s bone mass. In 2018, they demonstrated that taking vitamin D supplements led to changes in the activity of genes that are part of the vitamin D metabolic pathway.

In 2022, they found that taking this supplement during pregnancy can significantly reduce the risk of developing atopic eczema, a condition characterized by dry, itchy, and inflamed skin, in babies up to one year old. They also observed that pregnant women who were given extra vitamin D were more likely to have a spontaneous vaginal delivery or “natural” birth. According to Professor Nicholas Harvey, Director of the MRC Lifecourse Epidemiology Centre at the University, Professor of Rheumatology and Clinical Epidemiology, and project leader. He said: “These results complement the important findings obtained from the MAVIDOS study. We are deeply grateful to all the participating mothers and children. Their contributions have expanded our understanding of vitamin D supplementation and its role in strong and healthy bones.”