Sun's rays can reduce premature birth risk

Women who receive more sunlight in their first trimester lessen the chances of developing problems with their placenta associated with preterm birth and baby loss, researchers say.

The likelihood of those exposed to the lowest available sunlight to give birth prematurely was ten percent higher than women experiencing the highest levels, the team found.

Experts at the University of Edinburgh analyzed maternity care data for nearly 400,000 mothers and more than 500,000 babies born after 24 weeks of pregnancy.

Maternity records of all single live births in Scotland between 2000 and 2010 were then cross checked with postcode-specific weather records from the same period.

Sun exposure in the second trimester was not shown to have any impact on premature birth risk.

Shape advice

Researchers say their findings—which were independent of other risk factors such as age and smoking—could help shape the advice given to families during pregnancy.

The team says more work is needed to better understand the link between sunshine and premature birth. It is already investigating if artificial light can boost pregnancy health—to benefit parents in places with limited sunlight.

Complications caused by preterm birth—defined as babies born alive before 37 weeks of pregnancy—are the leading cause of death in children under five-years-old.

Survivors of preterm birth have higher rates of disability, including learning disabilities and visual and hearing problems, than those born at term.

Improved health

The team hopes further research can help develop ways to reduce preterm birth and subsequent childhood morbidity and mortality.

Researchers from the University of Edinburgh had previously shown that when our skin is exposed to the sun's rays, a compound—called nitric oxide—is released to our blood vessels that helps lower blood pressure.

This previous work suggested that exposure to sunlight improves health overall, because the benefits of reducing blood pressure far outweigh the risk of developing skin cancer.

Sunlight also directly contributes to vitamin D production, which helps with the development of an unborn baby's bones, teeth, kidneys, heart and nervous system.

Previous research from the same group has shown sunnier areas are associated with fewer deaths from COVID-19, and that increased sunlight exposure is linked to lower blood pressure and fewer heart attacks.

"The role of sunlight is an exciting new avenue for research into preterm birth prevention. This study is important because it provides further data reminding us that sunlight has health benefits as well as risks," says Dr. Sarah Stock, reader in maternal and fetal health at the University of Edinburgh's Usher Institute.