Risk of hypertensive disorders of Pregnancy linked to Seasonal Variations

in a study of Danish women, researchers have observed seasonal variations in the risk of hypertensive disorders of pregnancy—including gestational hypertension and preeclampsia. They have found that the highest risk for hypertensive disorders was seen in pregnancies conceived during spring and summer. The study has been published in the Acta Obstetricia et Gynecologica Scandinavica.

According to the American College of Obstetricians and Gynecologists, Hypertensive disorders of pregnancy constitute one of the leading causes of maternal and perinatal mortality worldwide. It has been estimated that preeclampsia complicates 2-8% of pregnancies globally. In Latin America and the Caribbean, hypertensive disorders are responsible for almost 26% of maternal deaths, whereas in Africa and Asia they contribute to 9% of deaths. Although maternal mortality is much lower in high-income countries than in developing countries, 16% of maternal deaths can be attributed to hypertensive disorders (). In the United States, the rate of preeclampsia increased by 25% between 1987 and 2004. 

Of 50,665 women included in the study, 8.5% were diagnosed with a hypertensive disorder of pregnancy. There appeared to be increasing risk when conceiving during the spring and early summer, peaking midsummer, and subsequently decreasing steadily during the autumn to reach a low by winter. Seasonal variations in vitamin D levels may help to explain these findings.

"Our results are of great interest, as vitamin D may have caused the observed seasonal variation in the hypertensive disorders. It has long been assumed that vitamin D affects the pathogenesis of hypertensive disorders of pregnancy—including preeclampsia—and our results support this hypothesis," said lead author Christine Rohr Thomsen, of Aarhus University Hospital, in Denmark.

For more details click on the link: https://doi.org/10.1111/aogs.13786