Hypothesis: The prevalence of sleep apnea is greater in pregnant women with preeclampsia than in pregnant women without preeclampsia.The presence of sleep apnea will be associated with poor blood pressure control, worsening blood pressure during sleep and evidence of fetal distress. The usual treatment for sleep apnea is to have the patient breathe pressurized air through a mask. This is called continuous positive airway pressure (CPAP). In preeclamptic women with sleep apnea, use of CPAP will result in improved blood pressure control and reduced fetal distress.