Effects of long-acting contraceptives on women's iron levels and responses to extreme environments

Influences of Long-acting Reversible Contraceptives on Iron Status and Physiological Responses to Extreme Environments in Women

This study is testing whether long-acting birth control methods can help military women keep their iron levels stable and perform better in extreme environments like heat and cold.

Quick facts

• Study type: Observational
• Enrollment: 33 (estimated)
• Ages: 18 Years to 40 Years
• Sex: Female
• Sponsor: United States Army Research Institute of Environmental Medicine (Federal)
• Locations: 1 site (Natick, Massachusetts)
• Trial ID: NCT06909695 on ClinicalTrials.gov

What this trial studies

This observational study investigates how long-acting reversible contraceptives (LARCs) like implants and IUDs affect iron status and physiological responses in military women exposed to extreme environments such as heat, cold, and high altitude. It aims to determine if LARCs, which are known to reduce menstrual blood loss, can help preserve iron stores and potentially improve health and performance. Participants will undergo blood volume and environmental testing to assess these impacts. The study focuses on women aged 18-40 who have been using LARCs or oral contraceptives for at least a year.

Who should consider this trial

Good fit: Ideal candidates are healthy females aged 18-40 who have been using LARCs or monophasic oral contraceptives for at least one year.

Not a fit: Patients who are not using LARCs or monophasic oral contraceptives, or those with health issues that prevent participation, may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could provide insights into how LARCs may improve iron status and overall health in women, particularly in demanding environments.

How similar studies have performed: While there is evidence suggesting LARCs may lower the prevalence of iron deficiency, this specific investigation into their effects on physiological responses in extreme environments is novel.

Eligibility criteria

Inclusion Criteria:

* • Females, age 18-40 y

  * Females taking monophasic oral contraceptives or utilizing implantable contraception (intrauterine device, implantable bar) for at least one year, and be at least one year removed from the removal end point (e.g. before year 4 for a 5-year IUD)
  * In good health as determined by OMSO (Office of Medical Support and Oversight)
  * Passed most recent Army Combat Fitness Test (ACFT) (military volunteers only) or exercise at least 2 times per week (civilian volunteers)
  * Willing to not drink alcoholic beverages for 24 hours before each testing session
  * Willing to not consume caffeine 12 hours prior to any testing sessions
  * Willing to refrain from any exercise and additional moderate to strenuous physical activity 24 hours prior to testing
  * Willing to stay and exercise in an altitude chamber (the size of a dorm room) for \~6 hours
  * Supervisor approval for federal civilian employees and non-HRV active-duty military personnel stationed at NSSC.

Exclusion Criteria:

* • Females who are pregnant, planning to become pregnant during the study, or breastfeeding.

  * Taking prescription, over the counter medication, or dietary supplements, other than a contraceptive (unless approved by OMSO and Principal Investigator (PI))
  * Tobacco or nicotine users, or anyone who has used tobacco or nicotine within the last four months
  * Physical problems/injuries (e.g., current stress fractures, musculoskeletal strains) that would affect walking or running on a treadmill
  * Allergy to skin adhesive
  * Heart, lung, kidney, muscle, endocrine, or nerve disorder(s) as determined by OMSO
  * History of heat intolerance or orthostatic intolerance
  * Diagnosed and/or treated for fluid/electrolyte imbalance within the last 30 days
  * History of obstructive disease of the gastrointestinal tract including (but not limited to) diverticulosis, diverticulitis and inflammatory bowel disease, peptic ulcer disease, Crohn's disease, ulcerative colitis.
  * Scheduled MRI within 2 weeks after completing a heat or cold test
  * Actively dieting with the intent to lose weight
  * History of cold injuries of any severity (e.g., frostbite, trench foot, chilblains).
  * Raynaud's syndrome
  * Cold-induced asthma/bronchospasm
  * Not willing to have small areas of skin on the body shaved (if deemed necessary for attachment of study instrumentation)
  * Born at altitudes greater than 2,100 m (7,000 ft) (e.g., Mexico City, Mexico)
  * Living in areas that are more than 1,200 m (4,000 ft) (e.g., Colorado Springs, CO) or have traveled to areas that are more than 1,200 m for five days or more within the last 2 months
  * Prior diagnosis of High Altitude Pulmonary Edema (HAPE) or High Altitude Cerebral Edema (HACE)
  * Abnormal blood count in accordance with OMSO - Normal Hb women: 11.1-15.9 g·dL-1 or Normal Hct women: 34.0-48%, or presence of abnormal blood chemicals (hemoglobin S or Sickle Cell Trait)
  * History of pneumothorax
  * History of hypertension
  * Blood donation within 8 weeks of beginning the study
  * Any recent (within 4-6 weeks) and or expected history of prolonged periods of immobility or limited activity (including recent or upcoming surgery)
  * Evidence of apnea or sleeping disorder (narcolepsy, insomnia, etc.)

Where this trial is running

Natick, Massachusetts

• US Army Research Institute of Environmental Medicine — Natick, Massachusetts, United States (Recruiting)

Study contacts

• Principal investigator: Gabrielle Giersch, PhD — United States Army Research Institute of Environmental Medicine
• Study coordinator: Gabrielle E Giersch, PhD

Conditions Contraception; Iron Deficiencies