Recruiting
Early Phase 1

IMST

Sponsor:

University of Arizona

Code:

NCT07687745

Conditions

Hypertension Disorders in Pregnancy

Blood Pressure Measurement in Pregnancy

Inspiratory Strength Training (IST)

Pregnancy

Eligibility Criteria

Sex: Female

Age: 18 - 55

Healthy Volunteers: Accepted

Interventions

Exercise at 15% PI max

Exercise at 50% PI max

Study Details

Brief summary:

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.

Conditions

Hypertension Disorders in Pregnancy

Blood Pressure Measurement in Pregnancy

Inspiratory Strength Training (IST)

Pregnancy

Study ID

NCT07687745

Start date

Jun 8, 2026

Status verified date

Jul, 2026

Completion date

Sep 30, 2027

Anticipated

Primary completion date

Jun 30, 2027

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: Female

Age: 18 - 55

Healthy Volunteers: Accepted

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 Design

Enrollment

80 participants

Anticipated

Allocation

Randomized

Intervention Model

Parallel Assignment

Primary purpose

Prevention

Interventions and Outcome Measures

Arms

sham comparator: Low-Resistance IMST

active comparator: Moderate-Resistance IMST

Interventions

Exercise at 15% PI max

Minimal resistance training, similar to yoga, for 5 to 8 minutes a day over six weeks.

Exercise at 50% PI max

Moderate resistance training, similar to strength training for 5 to 8 minutes a day over six weeks.

Primary outcome measure

  • Incidence of Maternal and Fetal Safety Events During Inspiratory Muscle Strength Training (IMST) [ Time Frame: 6 weeks ]
  • Adherence to IMST Training and Home Blood Pressure (BP) Monitoring [ Time Frame: 6 weeks ]
  • Change from Baseline in Systolic Blood Pressure [ Time Frame: 6 weeks ]
  • Change from Baseline in Endothelial Function as Assessed by Post-Occlusive Reactive Hyperemia (PORH) [ Time Frame: 6 weeks ]
  • Change from Baseline in Urinary Nitrite/Nitrate Concentration [ Time Frame: 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. ]

Central Contacts and Locations

Central contacts

Elise Erickson, PhD

520-621-1139eliseerickson@arizona.edu

Lily Woods, MA

520-621-1139lilywoods@arizona.edu

Locations

Banner University Medical Center

Recruiting

Tucson, Arizona, United States, 85719

Contacts

Rachel Darche, MD

520-621-1139rldarche@arizona.edu

More Information

Sponsor

University of Arizona

Last update posted

Jul 7, 2026

Last verified

Jul, 2026

Keywords

  • pregnancy
  • blood pressure
  • hypertensive disorders of pregnancy
  • imst
  • hdp
  • inspiratory muscle strength training

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-10. This information was provided to ClinicalTrials.gov by University of Arizona on 2026-07-07.