Breathing for Two: Inspiratory Muscle Strength Training for Supporting Healthy Blood Pressure in Pregnancy

This study is looking at whether a breathing exercise called Inspiratory Muscle Strength Training (IMST) can safely and effectively help lower blood pressure during late pregnancy. You would be in your third trimester (32 to 34 weeks pregnant) and randomly assigned to do either moderate resistance IMST or a minimal resistance IMST for 5 to 8 minutes a day over six weeks. The main goals are to see if this training is safe for pregnant women and to check its effect on blood pressure. This study is currently unclear on its recruitment status and plans to enroll 80 pregnant women.

Study design: This is an interventional study that will randomly assign 80 participants to one of two groups: moderate resistance IMST or minimal resistance IMST.
What's involved: You would perform breathing exercises for 5 to 8 minutes a day over six weeks. You will also need a smartphone to sync devices and complete online surveys.
Compensation: Not stated in the trial record.
Follow-up: The primary endpoints are measured at 6 weeks, which is the duration of the intervention.

AI-generated from the public study record. Only the study team can confirm whether you're eligible — confirm details with them before making decisions.

Breathing for Two: Inspiratory Muscle Strength Training for Supporting Healthy Blood Pressure in Pregnancy

Recruiting

EARLY_PHASE1Ages 18–55InterventionalPrevention

University of Arizona

~80 participants

Updated 2026-07-07 on ClinicalTrials.gov

What's tested:Exercise at 15% PI maxExercise at 50% PI max

At a glance

Recruiting sites

1 of 1 listed site is recruiting right now

RecruitingSuspended, closed, or not yet open

What they're measuring

Incidence of Maternal and Fetal Safety Events During Inspiratory Muscle Strength Training (IMST)

Measured over 6 weeks

+4 more outcomes measured

Conditions

Hypertension Disorders in Pregnancy

Blood Pressure Measurement in Pregnancy

Inspiratory Strength Training (IST)

Pregnancy

NCT07687745

Where you'd take part

This study runs at 1 site. They're the same protocol — you choose where, and that choice sets who your contact draft is addressed to.

Banner University Medical Center
Tucson, Arizonastudy coordinator listed
Recruiting

Sites open and close at different times, so the status above is per site — it can differ from the study's overall status.

Who to contact

Elise Erickson, PhD

[email protected]

520-621-1139

Email the study team

Opens a ready-to-send draft in your own email app — review before sending.

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Add a private profile and we'll compare every criterion below against your situation — and tell you which ones are met, uncertain, or excluding.

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Eligibility criteria

Inclusion

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)

No history or evidence of hypertensive disorders of pregnancy

May be undergoing antenatal testing for:

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

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)

What this trial measures

Incidence of Maternal and Fetal Safety Events During Inspiratory Muscle Strength Training (IMST)6 weeks
Percentage of training sessions associated with abnormal post-training fetal heart rate (FHR) tracing, or with maternal oxygen desaturation (SpO2) or symptoms (e.g., perceived exertion, lightheadedness, hyperventilation), as assessed by study staff during non-stress test (NST) and clinic visits.
Adherence to IMST Training and Home Blood Pressure (BP) Monitoring6 weeks
Percentage of prescribed daily IMST training sessions and daily home BP measurements completed by each participant, as captured via training device data and MyCap entries.
Change from Baseline in Systolic Blood Pressure6 weeks
Change in systolic BP (mmHg), measured via validated automated oscillometric sphygmomanometer (Omron BP7450) per ESH-IP protocol, comparing IMST and sham IMST groups.
Change from Baseline in Endothelial Function as Assessed by Post-Occlusive Reactive Hyperemia (PORH)6 weeks
Change in cutaneous microvascular blood flow response (perfusion units) following brief arterial occlusion, measured via Laser Doppler Blood FlowMetry, comparing IMST and sham IMST groups.
Change from Baseline in Urinary Nitrite/Nitrate ConcentrationChange in urinary nitrite/nitrate concentration (µM), measured weekly via Griess colorimetric assay (Cayman Nitrite Colorimetric Assay), as an indirect marker of nitric oxide bioavailability.
6 weeks

Trialytics