Are There Sleep-related Factors That Contribute to an Increased Incidence of Pre-eclampsia at Altitude?

It is known that high altitude increases the risk of preeclampsia and small for gestational age births. Our questions are: 1). Is sleep apnea during pregnancy more common and/or more severe at altitude? And 2) Do the women who develop preeclampsia at altitude have more severe sleep apnea, or worse hypoxemia during sleep, than the women at altitude who do not develop preeclampsia. We will perform WatchPAT-one home sleep tests (PAT = peripheral arterial tonometry) on up to 20 pregnant women in Summit County Colorado (\>9000 ft.elevation) who develop preeclampsia during pregnancy (soon after diagnosis), and also on up to 20 pregnant healthy women in Summit County, and 20 healthy pregnant women in Baltimore (at sea level). These healthy pregnant women in Summit County and Baltimore will be selected from volunteer participants, to best match age, pre-pregnancy BMI, and race with individuals in Summit County who are studied with preeclampsia and they will be studied at the gestational timing that matches their Summit County preeclampsia matching subject. In addition to the up to 20 healthy pregnant subjects at Summit County and 20 in Baltimore, who match the preeclampsia subjects, we will recruit up to 20 more in Summit County and 20 more in Baltimore, to study specifically in the 33rd or 34th gestational week, to improve our ability to evaluate the effects of altitude on sleep apnea, during pregnancy. Information on the births, including height and weight and apgar scores will be assessed, in part to see whether sleep apnea during pregnancy affects outcomes. All sleep studies will be scored at the JHH (Johns Hopkins Hospital) Bayview sleep lab's Center for Interdisciplinary Sleep Research and Education.