Sleep Apnea and Fetal Growth Restriction

Inclusion Criteria: * Age ≥ 18 and ≤ 50 * Fetal growth restriction (defined as fetal weight \<10th percentile based on at least one routine 2nd trimester ultrasound without a subsequent increase to \>15th percentile on any ultrasounds prior to enrollment) * Lower limit of gestational age at enrollment 22+0 weeks. * Upper limit of gestational age at enrollment: adequate time to complete Stages 1 and 2 and if appropriate to be randomized and receive intervention by no later than 32+0 weeks. * The absence of 2 minor or 1 major markers of aneuploidy. Exclusion Criteria: * Other known cause of fetal growth restriction (including congenital anomalies, intrauterine infection, or multiple gestation) * Reversed end-diastolic flow in the umbilical artery * Preexisting diagnosis of OSA being treated with aPAP * Chronic pulmonary disease (cystic fibrosis, moderate persistent asthma) * Hemoglobinopathies (sickle cell anemia, thalassemia) * Maternal craniofacial anomalies * Premature rupture of membranes