Many pregnant women suffer from poor sleep quality and snoring. Evidence shows an increasing association between (1) sleep disordered breathing and (2) maternal cardiovascular disease and in-hospital death. Snoring is a variant of obstructive sleep apnea (OSA) and OSA during pregnancy is associated with higher risks for cesarean delivery, gestational hypertension, preeclampsia and preterm delivery. It may also impact fetal outcomes negatively. The purpose of this study is to determine whether sleep quality can be improved in pregnant women who snore by means of an oral appliance that opens the airway. Sleep quality is evaluated objectively using an un-intrusive home sleep test system.