Introduction
Obstructive sleep apnea (OSA) is a high-prevalence disease, sometimes exceeding 50% in the general population.1–4 The intermittent hypoxia and fragmentation of sleep it engenders are risk factors for cardiovascular diseases, especially for chronic hypertension, metabolic syndrome, and diabetes.2–5Clinically, this disorder is manifested principally by two symptoms: daytime somnolence and nocturnal snoring. Polysomnography in a sleep laboratory is the reference examination for this diagnosis, defined by calculating the apnea-hypopnea index (AHI). In Western countries, the prevalence of mild OSA (AHI ≥ 5) has been estimated at 9–38% and that of moderate to severe OSA (AHI ≥ 15) at 6–17%.2These variations are explained by differences in the diagnostic criteria, but also by the heterogeneity of study populations; prevalence is higher among men, the elderly, and obese women. Obesity is its principal risk factor.
Obesity in pregnant women is accompanied by an increase in pregnancy-related vascular complications such as preeclampsia, pregnancy-related hypertension, and gestational diabetes.6,7 Other obstetric complications are associated with an impaired quality of labor (higher rate of post-term pregnancies, prolonged labor, and cesareans for cervical dystocia) 8-13 and a higher risk of postpartum hemorrhage in vaginal deliveries.9 Obesity in pregnant women may also be a risk factor for the development of sleep apnea, which may further increase the risk of pregnancy complications.
OSA during pregnancy has been studied often. Depending on the definition used and the study, its prevalence among women of child-bearing age has been estimated at 1.4–16.9%.2,14,15 But the exact prevalence among pregnant women remains unknown, especially because it is underestimated and underdiagnosed in this population because of its nonspecific clinical symptoms during pregnancy (asthenia, nonrestorative sleep, snoring in the third trimester) that may thus be trivialized by both women and clinicians.16,17 Moreover, because many of the studies about OSA and pregnancy have not used polysomnography, it may well have been either under- or overdiagnosed.
Substantially less is known about the effects of OSA in pregnant women than in nonpregnant populations. Recent data indicate it is associated with higher risks of gestational diabetes, preeclampsia, and fetal growth restriction (FGR). A meta-analysis published in 2018 showed that women with OSA are also at higher risk of preterm, cesarean, and operative vaginal deliveries, as well as of postoperative complications.18 Nonetheless, most of the data currently available is limited to case reports or studies without either or both of an appropriate, objective test to diagnosis OSA and adjustment for obesity, an obvious confounding factor.19,20
Few studies have specifically explored OSA in pregnant women with obesity. We therefore chose to conduct a study in this population: its principal objective was to define their prevalence of OSA. Our hypothesis was that its prevalence would be higher among them than among non-obese women. Our secondary objectives were to compare the women with and without OSA for the course and outcomes of their pregnancy and to identify some of its predictive factors.