Pregnant women who experience certain breathing problems during sleep may be more likely to develop complications like high blood pressure and diabetes, recent US research suggests.
In the study of more than 3,000 women, researchers did home-based sleep studies twice during pregnancy to check for what's known as apnea, a potentially serious sleep disorder that involves repeated stops and starts in breathing. Risk factors for sleep apnea include older age and obesity.
Women who had sleep apnea were almost twice as likely to develop what's known as preeclampsia, a type of pregnancy-related high blood pressure, and up to 3.5 times more likely to develop pregnancy-related diabetes, the study found.
"Although we found an association with sleep disordered breathing preceding the development of both pregnancy-related hypertensive disorders and gestational diabetes, we cannot conclude that universal screening for, and treatment of sleep disordered breathing in pregnancy would reduce the risks of these adverse outcomes," said lead study author Dr. Francesca Facco of the University of Pittsburgh's Magee-Women's Hospital.
That's because even among people who are not pregnant, there isn't conclusive evidence that the most common treatment for apnea can reduce the risk of developing hypertension or diabetes, Facco said by email.
For the most common apnea treatment, patients wear breathing masks at night. The masks are connected to a machine that provides continuous positive airway pressure (CPAP), which splints the airway open with an airstream so the upper airway can't collapse during sleep.
Some patients can't tolerate sleeping with CPAP machines. This intervention may not make sense for pregnant women, particularly if they have only mild apnea, Facco said.
"We do not know if treating sleep-disordered breathing in pregnancy will improve clinical outcomes in pregnancy, and our study cannot answer that question," Facco added.
Sleep tests done for the study found that early in pregnancy, between six and 15 weeks gestation, 3.6 per cent of the women had apnea. Later in pregnancy when they had gained more weight, between 22 and 31 weeks gestation, 8.3 per cent of the women had apnea.
Overall, 6 per cent of the women had preeclampsia, 13 per cent had pregnancy-related hypertensive disorders and 4 per cent developed gestational diabetes, researchers report in the journal Obstetrics and Gynecology.
Early in pregnancy, women with apnea were 94 per cent more likely to develop preeclampsia, 46 per cent more likely to have hypertensive disorders and 3.5 times more likely to develop diabetes than women without sleep disordered breathing.
Women who had apnea later in pregnancy were 95 per cent more likely to develop preeclampsia, 73 per cent more likely to develop hypertensive disorders, and 2.8 times more likely to have diabetes than women without sleep disordered breathing.
The study is observational and doesn't prove apnea causes these pregnancy complications.
One limitation of the study is the potential for home-based sleep tests to leave some cases of apnea undetected, potentially underestimating the prevalence of sleep-disordered breathing.
"Currently, we still need more data on whether improving or treating sleep-disordered breathing will lessen the risk of high blood pressure or diabetes during pregnancy," said Dr. Sirimon Reutrakul, a researcher at Mahidol University in Bangkok who wasn't involved in the study.
"However, overweight or obesity is a risk factor for high blood pressure and diabetes during pregnancy, as well as sleep-disordered breathing," Reutrakul added by email. "Therefore, keeping healthy body weight through diet and exercise should lessen the risk for these problems."
Women have many health reasons to start pregnancy at a healthy weight and a younger age, two things that may also lower the odds for apnea, said Dr. Marie-Pierre St-Onge, a researcher at Columbia University Medical Center in New York who wasn't involved in the study.
"Obstructive sleep apnea is associated with obesity," St-Onge said by email.
"Although this study did not find an interaction between weight status and OSA on hypertension and diabetes, I would suggest that women enter pregnancy at a normal weight and gain weight appropriate for their weight status," she said.
"Whenever possible, avoiding delaying pregnancy to a more advanced age would be advisable," St-Onge added.