This study will evaluate the presence or absence of Obstructive Sleep Apnea (OSA) in the third trimester of pregnancy and again postpartum.

This is a prospective cohort study to evaluate the presence or absence of OSA in the third trimester of pregnancy and again postpartum. The investigators will use the Watch-PAT200® device as their accepted standard for diagnosis of obstructive sleep apnea.

When enrolled, women will be taught how to use the Watch-PAT200® via a company produced video that will be shown in the clinic and will be available via YouTube for review later if needed. They will also complete the Berlin Questionnaire. The patient will then use the Watch-PAT200® device overnight to evaluate for obstructive sleep apnea. This will be performed between 32-36 weeks gestation. Apnea-hypopnea indices (AHI) will be calculated and an AHI>5 will be considered diagnostic for OSA.

The next morning when the patient returns the Watch-PAT200® device they will exhale into the NIOX MINO® to assess their exhaled nitric oxide levels. This will be performed between 800-1000 am by one of the study personnel.

The patient will also wear the Watch-PAT200® device the first postpartum night. The entire process will be repeated between 6-8 weeks postpartum.

Inclusion Criteria:

• Female (> or equal 18 year of age)
• Pregnant between 32 0/7 prior to 35 6/7 weeks gestation
• Anticipated delivery at Forsyth Medical Center: Winston Salem, North Carolina

Exclusion Criteria:

• Illicit drug/Alcohol abuse
• Current treatment for obstructive sleep apnea
• Age <18 years
• Inability to speak/read English proficiently enough to give informed consent
• Usage of alpha blockers or short acting nitrates
• Permanent pacemaker
• Sustained non-sinus cardiac arrhythmias

Pregnant women between 32 0/7 prior to 35 6/7 weeks gestation