• Female sex - Pregnant (32 to 34 weeks of gestation, confirmed by ultrasound, at the time of first training session, eligible patients may consent/enrolled earlier in pregnancy) - Singleton pregnancy - Age 18 to 55 - Able to read English and provide consent - Possess smartphone for syncing the AiroFit and Omron devices using Bluetooth and completing online surveys - Smartphone updated to iOS 12+ or Android 11+ - No contraindication for moderate exercise at time of enrollment - Not planning delivery for at least one month at time of enrollment (< 38 weeks of gestation) - Willing to adhere to AiroFit device use throughout study period - Must already be scheduled, or in the process of scheduling, for weekly NST appointments by 32 to 34 weeks gestational age (per provider order / due to obstetric indication) Lower-Risk Pregnancy Cohort Inclusion Criteria: - No history or evidence of hypertensive disorders of pregnancy - May be undergoing antenatal testing for: - Conception via in vitro fertilization, BMI ≥ 35, an advanced maternal age (age >/=35), or other condition not listed in

or 'higher risk for HDP group' but is recommended for antenatal testing. Higher-Risk Pregnancy Cohort Inclusion Criteria: - Conditions associated with higher risk of developing HDP, including: - Gestational diabetes mellitus, chronic hypertension, gestational hypertension, or a history of preeclampsia in a previous pregnancy Exclusion Criteria: - Younger than 18 or older than 55 years of age - Multiple gestation (twin or higher-order pregnancy) - Fetal chromosomal abnormalities or major anatomical anomalies - Planning to deliver earlier than 38 weeks or within 4 weeks of study enrollment - Any contraindication for moderate exercise (e.g., cardiomyopathy, congenital cardiac conditions) - Deep vein thrombosis - Complications in current pregnancy including intrauterine growth restriction (IUGR), oligohydramnios, preeclampsia, or severe-range blood pressures (>/=160/110 or <100/60) - Active vaginal bleeding, or history of coagulopathy - Placenta previa or other placental abnormalities (including placental cyst or abruption) - Signs of labor - Current substance use disorder - History of neurological, respiratory, head/neck, or thoracic surgeries, or conditions such as collapsed lung or perforated eardrum - Individuals with any of the following: - Chronic obstructive pulmonary disorder (COPD) - Severe asthma - Severe ischemic heart disease - Left-sided heart failure - Chronic laryngitis, chronic bronchitis, emphysema, pneumonia - Latent or active tuberculosis - Chronic cough - Neurological problems (e.g. seizure disorder) - Severe scoliosis with no history of surgical correction or management. - Organ transplant - HIV or other immunocompromising conditions - Autoimmune disease with possible vascular complications (e.g. Lupus) - Significant respiratory compromise (e.g., severe dyspnea, O₂ saturation <95%, uncontrolled asthma, history of pneumothorax)