Obstructive Sleep Apnea Among Pregnant Women With Chronic Hypertension

The purpose of this study is to identify whether pregnant women with chronic hypertension are at significantly higher risk of having undiagnosed OSA and should be routinely screened with home sleep tests. The investigators will recruit 120 pregnant subjects between 10-20 weeks gestation from the Duke High Risk Obstetrics Clinic over a 20-month period. They will be enrolled into one of two groups: 1) chronic hypertension (on medication or hypertensive blood pressures documented at 3 clinic visits); 2) normal blood pressure, and not on any treatment for chronic HTN and no history of chronic HTN, and matched for BMI (+/- 3 kg/m2) with the chronic HTN group. The two groups will be matched for BMI to control for the effect of obesity on OSA diagnosis and cHTN. The primary hypothesis, that OSA prevalence differs between patients with chronic HTN and normotensive controls, will be assessed with a two-group two-sided Fisher's exact test. A Fisher's exact test with a 0.05 two-sided significance level will have 92% power to detect the difference between a normotensive OSA rate of 0.10 and a chronic hypertensive OSA rate of 0.40 when the sample size in each group is 50. There are no risks associated with the use of the home sleep test device, but subjects that have a severe latex allergy should not participate, as the device