Obstructive Sleep apnea (OSA) is a common and underdiagnosed condition in obese pregnant women with serious and life-threatening complications to the mother and baby. The investiators propose that a non-invasive method may be used to detect patients at risk of OSA, giving these women access to the necessary treatment to treat this condition. The method is a estimation of body water, which has been shown to be linked to OSA in the non-pregnant population. Body water is estimated by applying surface electrodes to a participant who is lying down by measuring bioimpedance through body tissues by applying a tiny current between the electrodes. The electrical stimulation is not felt by the participant and has no negative effects on mother or baby.