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

This is an interventional study that will test whether a breathing exercise called Inspiratory Muscle Strength Training (IMST) can safely and effectively lower blood pressure during late pregnancy. The goal is to see if a home-based breathing training can help prevent or reduce high blood pressure disorders in pregnancy. The main objectives are to make sure the training is safe and tolerable for pregnant women and to examine blood pressure and blood vessel health. Participants in their third trimester will be randomly assigned to either do moderate resistance IMST or a minimal resistance sham IMST, for 5 to 8 minutes a day over six weeks.

Study Overview

• Status: Recruiting
• Conditions: Pregnancy; Hypertension Disorders in Pregnancy; Blood Pressure Measurement in Pregnancy; Inspiratory Strength Training (IST)
• Intervention / Treatment: Other: Exercise at 15% PI max; Other: Exercise at 50% PI max

• Study Type: Interventional
• Enrollment (Estimated): 80
• Phase: Early Phase 1

Contacts and Locations

• Study Contact: Name: Elise Erickson, PhD; Phone Number: 520-621-1139; Email: eliseerickson@arizona.edu
• Study Contact Backup: Name: Lily Woods, MA; Phone Number: 520-621-1139; Email: lilywoods@arizona.edu

Study Locations

• United States
  • Arizona
    • Tucson, Arizona, United States, 85719
      • Recruiting
      • Banner University Medical Center
      • Contact: Rachel Darche, MD; Phone Number: 520-621-1139; Email: rldarche@arizona.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• 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 exclusion criteria 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)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Sham Comparator: Low-Resistance IMST	Other: Exercise at 15% PI max; Minimal resistance training, similar to yoga, for 5 to 8 minutes a day over six weeks.
Active Comparator: Moderate-Resistance IMST	Other: Exercise at 50% PI max; Moderate resistance training, similar to strength training for 5 to 8 minutes a day over six weeks.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Incidence of Maternal and Fetal Safety Events During Inspiratory Muscle Strength Training (IMST)	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.	6 weeks
Adherence to IMST Training and Home Blood Pressure (BP) Monitoring	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.	6 weeks
Change from Baseline in Systolic Blood Pressure	Change in systolic BP (mmHg), measured via validated automated oscillometric sphygmomanometer (Omron BP7450) per ESH-IP protocol, comparing IMST and sham IMST groups.	6 weeks
Change from Baseline in Endothelial Function as Assessed by Post-Occlusive Reactive Hyperemia (PORH)	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.	6 weeks
Change from Baseline in Urinary Nitrite/Nitrate Concentration	6 weeks	Change in urinary nitrite/nitrate concentration (µM), measured weekly via Griess colorimetric assay (Cayman Nitrite Colorimetric Assay), as an indirect marker of nitric oxide bioavailability.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change from Baseline in Perceived Sleep Quality	Change in self-reported sleep quality as measured by the PROMIS Sleep Disturbance short form, administered weekly via MyCap.	6 weeks
Change from Baseline in Dyspnea Severity	Change in self-reported shortness of breath severity as measured by the PROMIS Dyspnea Severity items, administered weekly via MyCap.	6 weeks
Change from Baseline in Perceived Stress	Change in perceived stress as measured by the Perceived Stress Scale (PSS), administered weekly via MyCap.	6 weeks

Collaborators and Investigators

• Sponsor: University of Arizona
• Collaborators: Banner University Medical Center

Publications and helpful links

Helpful Links

• Related Info

Study record dates

Study Major Dates

• Study Start (Actual): June 8, 2026
• Primary Completion (Estimated): June 30, 2027
• Study Completion (Estimated): September 30, 2027

Study Registration Dates

• First Submitted: June 8, 2026
• First Submitted That Met QC Criteria: July 1, 2026
• First Posted (Actual): July 7, 2026

Study Record Updates

• Last Update Posted (Actual): July 7, 2026
• Last Update Submitted That Met QC Criteria: July 1, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: pregnancy; blood pressure; inspiratory muscle strength training; hypertensive disorders of pregnancy; imst; hdp
• Other Study ID Numbers: STUDY00007216

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: All IPD that underlie results in a publication will be shared, after any identifying information is removed from the dataset.
• IPD Sharing Time Frame: Upon publication, for a period of 2 years, the IPD will be available using a publicly available repository/storage system (e.g. Open Science Framework or similar).
• IPD Sharing Access Criteria: Any data that is made publicly available can be accessed without permission/restriction. Beyond the initial 2 year period, data can be made available upon reasonable request to the PI.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF; ANALYTIC_CODE

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes
• product manufactured in and exported from the U.S.: Yes