Sleep apnoea is a potentially serious sleep disorder in which breathing repeatedly stops and starts. A new study by researchers examined whether sleep disordered breathing (primarily obstructive sleep apnea) during pregnancy and in the years after delivery is associated with an increased risk for hypertension and metabolic syndrome. 

The study was published online in the American Thoracic Society's American Journal of Respiratory and Critical Care Medicine. Metabolic syndrome consisted of a cluster of conditions that increased the risk of heart disease, stroke and diabetes. In "Sleep Disordered Breathing in Pregnancy and Post-Delivery: Associations with Cardiometabolic Health," Francesca L. Facco, MD, assistant professor, Department of Obstetrics, Gynecology & Reproductive Science, Division of Maternal-Fetal Medicine, UPMC Magee-Women's Hospital, Pittsburgh, and colleagues conducted sleep apnoea tests.

Participants were a subgroup of 1,964 women who were part of the Nulliparous Pregnancy Outcomes Study: Monitoring Mothers-to-be Heart Health Study (nuMoM2b-HHS) and were experiencing their first pregnancy, and 1,222 of the same study participants who were examined 2-7 years after delivery. The researchers then determined whether participants were at increased risk for hypertension or metabolic syndrome.

"While epidemiologic data from cohorts of middle-aged and older adults indicate that sleep-disordered breathing is associated with adverse cardiometabolic outcomes, less is known about how sleep-disordered breathing in pregnancy and in the post-delivery period impacts maternal health," stated the authors.

Sleep-disordered breathing during pregnancy has been associated with a two to three-fold increased risk for preeclampsia--persistent high blood pressure during pregnancy that can lead to serious health consequences--and/or gestational diabetes (diabetes that develops during pregnancy). These and other adverse pregnancy outcomes are risk factors for later development of hypertension and metabolic disease in the mother.

Study participants were tested both during pregnancy and two to seven years later, each using the same model home sleep apnoea test. Among other factors, sleep apnoea tests measure the number of times a person experiences breathing pauses and associated drops in oxygen levels. Study participants were considered to have sleep apnoea if they experienced five or more breathing pauses or drops in oxygen during their estimated sleep period.

"We found that the presence of sleep apnoea measured both during pregnancy and two to seven years after delivery was associated with the development of hypertension and metabolic syndrome," said Dr Facco.In addition, participants with sleep apnoea that persisted during pregnancy and the two-to-seven-year follow-up visit were at more than the three-fold increased risk for incident hypertension and a more than the two-fold increased risk for metabolic syndrome compared to participants who never had an abnormal sleep study. Incident hypertension is defined as the first occurrence at any follow-up visit of systolic blood pressure 140 mm Hg or higher or diastolic blood pressure 90 mm Hg or higher.

"Our data also demonstrated a higher risk of developing metabolic syndrome and hypertension using a simple measurement of oxygen dips per hour of sleep," said study co-author Susan Redline, MD, MPH, who directs the Sleep Medicine Epidemiology program at Brigham and Women's Hospital and Harvard Medical School, Boston.

"These results suggest that use of simple oxygen monitoring devices may be useful for identifying women in pregnancy and in the post-delivery period at risk for adverse health outcomes and identifying women who may potentially benefit from treating sleep apnoea ."

"These data underscore the need to rigorously evaluate the role of screening and treating sleep apnoea during pregnancy and in the post-delivery period as new strategies for early interventions aimed at improving long-term maternal health," the authors concluded.