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.

Preterm birth (birth at <37 weeks gestation) is the leading cause of death in children under 5-years-old, and prevention is a global public health issue. The aim was to determine the association between available sun exposure and preterm birth.

Investigators performed a population-based data-linkage study of 556,376 singleton births at or after 24 weeks gestation. Maternity records were linked to available sun exposure from meteorological records, by postcode. Logistic regression analysis was used to explore the relationship between available sunshine and preterm birth at <37 weeks gestation.

- The rate of preterm birth was 6%. Increased available sun exposure in the first trimester of pregnancy was associated with a reduced risk of preterm birth, with evidence of a dose-response.

- Compared with the lowest quartile of sun exposure, the highest quartile of sun exposure was associated with a reduced odds ratio (OR) of preterm birth of 0.90 on univariable analysis and OR of 0.91 after adjustment for second-trimester sunlight exposure, parity, maternal age, smoking status, and deprivation category.

- No association was seen between preterm birth and second-trimester available sun exposure or combined first and second-trimester exposure.

- Similar patterns were seen on sibling analysis and within both the indicated and spontaneous preterm subgroups.

Overall, available sun exposure in the first trimester of pregnancy is associated with a protective effect on preterm birth <37 weeks gestation. This opens up new mechanisms, and potential therapeutic pathways, for preterm birth prevention.

Frontiers in Reproductive Health