Central sleep apnea in pregnant women with sleep disordered breathing

Physiologic changes in the cardiac, respiratory, and renal systems in pregnancy likely impact ventilatory control. Though obstructive sleep apnea and snoring are common in the pregnant population, the predisposition to central respiratory events during sleep and the prevalence of such events is less well studied. The aim of this study was to assess the presence of central apneas during sleep in pregnant women and non-pregnant controls suspected of sleep disordered breathing. Twenty-five pregnant women referred for polysomnography for sleep disordered breathing were compared with non-pregnant controls matched for age, body mass index, gender, and apnea hypopnea index (AHI). Central apnea index was defined as the number of central apneas per hour of sleep, and mixed apnea index was defined as the number of mixed apneas per hour of sleep. Sixty-four percent of pregnant women had a respiratory disturbance index > 5 events per hour of sleep. Mean body mass index was 44.1 +/- 6.9 kg/m(2) pregnant compared to 44.0 +/- 7.3 kg/m(2) in controls. The total number of central apneas observed during sleep in the pregnant group consisted of two central apneas in one patient, and of 98 central apneas in 11 patients in the control group (p = 0.05). Median central apnea index was low in both groups (pregnant 0, interquartile range (IQR) 0, 0 vs. non-pregnant 0, IQR 0, 0.2, p = 0.04). Mixed apnea index was similarly low in both groups. Despite some physiologic changes of pregnancy that impact ventilatory control, the prevalence of central sleep apnea was low in our sample of overweight pregnant women with sleep-disordered breathing.