Sleep Apnea Common in Pregnant Obese Women

By Scott Baltic

March 18, 2019

NEW YORK (Reuters Health) - Undiagnosed, mild obstructive sleep apnea (OSA) is common in late pregnancy among women who are obese, U.S. researchers report.

The small prospective study also found that poor sleep and OSA might contribute to increased glycemic profiles and insulin resistance.

OSA is "an underappreciated but potentially treatable target to optimize maternal glycemia and metabolism, fetal fuel supply and pregnancy outcomes," the researchers report in the Journal of Clinical Endocrinology & Metabolism, online February 22. Their study, they note, is the first to demonstrate that poor sleep and undiagnosed mild OSA are common in late pregnancy complicated by obesity.

It was also the first to show a significant correlation between OSA severity and higher levels of 24-hour glucose, increased fasting free fatty acids and glycerol, markers of lipolysis, and adipose insulin resistance in pregnant women, even when diet is controlled.

The research involved 18 women (mean age 29) at a single center with a mean BMI of 34.3, a singleton pregnancy, and a normal glucose-tolerance test at 24-28 weeks of pregnancy. A diagnosis of diabetes was cause for exclusion.

The study took place during the participants' gestational week 32-34. The participants consumed a 48-hour fixed eucaloric diet of 50% carbohydrate, 35% fat and 15% protein. Each wore a Dexcom G4 continuous-glucose-monitoring sensor for 72 hours, as well as a WatchPAT200 to monitor their sleep over three consecutive nights.

There was one pre-term birth, due to pre-eclampsia. Four women had cesarean sections; one was unplanned, and caused by failure to progress. Overall, infants were full-term and birth weights were appropriate for gestational age.

Based on apnea hypopnea index (AHI), six women had mild OSA, five had moderate OSA and one had severe OSA. Across all participants, women slept about six hours per night and sleep efficiency was low.

Mean 24-hour glucose was significantly higher in women with OSA than in those without OSA.

Strong positive associations were seen between AHI and markers of lipolysis and estimated hepatic insulin resistance, leading the researchers to suggest a strong connection between sleep disorders and insulin resistance in pregnancy.

The findings indicate that "in women who do not have gestational diabetes, there is still a relationship between undiagnosed sleep apnea and higher glucose patterns throughout the day," said Dr. Sarah Farabi of the Goldfarb School of Nursing, in St. Louis, Missouri, who worked on the study.

"This is important because, without a gestational diabetes diagnosis, these women do not receive extra fetal monitoring (or) treatment with diet therapy, or check their blood sugars using a glucometer," she told Reuters Health by email.

She added that the results "suggest that women, especially those with obesity, should be screened for OSA in pregnancy, in part because it could contribute to higher levels of glucose, abnormal fetal growth, or adverse pregnancy outcomes."

It's not known whether treatment of OSA in pregnancy will prevent complications, Dr. Farabi said, "although it is expected that there will be benefits, given that treatment of OSA in non-pregnant women results in improvement of glucose tolerance and hypertension."

Periods of low oxygen to the fetus caused by maternal OSA could affect neurological development or growth, Dr. Farabi said, adding that large randomized trials evaluating the effects of treating OSA in pregnancy on maternal and neonatal complications are needed.

Dr. Francesca Facco of the department of obstetrics and gynecology at Magee-Womens Hospital, in Pittsburgh, Pennsylvania, told Reuters Health that the study is well done and noted that prior cohort studies have found that OSA in pregnancy is associated with an increased risk of gestational diabetes.

Data from cohort studies, she said in an email, have demonstrated that obese women without gestational diabetes are at increased risk of complications such as macrosomia. The findings of the current work, she said, "suggest that undiagnosed sleep apnea may be a contributing factor."

Dr. Facco, who was not involved in the research, added that the National Institutes of Health Maternal-Fetal Medicine Units Network has begun a randomized controlled trial on treating OSA with continuous positive airway pressure. "Data from this trial will help us understand if screening and treating sleep apnea in pregnancy has the potential to improve maternal and infant outcomes," she said.

The study did not have commercial funding, and the authors reported no conflicts of interest.


J Clin Endocrinol Metab 2019.