ContraceptionNCT06909695
Influences of Long-acting Reversible Contraceptives on Iron Status and Physiological Responses to Extreme Environments in Women
An observational study of Contraception and Iron Deficiencies, run by United States Army Research Institute of Environmental Medicine at 1 site in United States.
Trial summary
Over recent years, military service women have shown increasing interest in utilizing long-acting reversible contraceptives (LARCs; i.e., implants or intrauterine devices, IUDs). Read more about this study
- Who is it for?
- Ages 18 to 40 years, women onlyHealthy volunteers can take part
- Conditions the study is for
- Contraception, Iron Deficiencies
- What is being tested?
- Blood volume and environmental testing
- Type of treatment
- Pill or oral medicine, Injection or infusion
- How many people
- 33 participants
- Where
- 1 siteUnited States
- Study dates
- 1 Nov 2024to Sep 2027
- Phase
- Observational
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 40 years
- Women only
- Healthy volunteers accepted
- Adult
Study population: The proposed population will be healthy and active women between the ages of 18-40. This population is suitable for the purpose of this investigation since they are the most militarily relevant population (i.e., representative of the U.S. Army active duty population).
Who may be able to join
- • 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
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- 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.
Who cannot join
- • 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
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- 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.)
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site, 1 recruiting
- Recruiting
US Army Research Institute of Environmental Medicine
Natick, Massachusetts, 01760
Gabrielle Giersch, PhD, 508-206-2421, gabrielle.e.giersch.civ@health.mil
About this study
Over recent years, military service women have shown increasing interest in utilizing long-acting reversible contraceptives (LARCs; i.e., implants or intrauterine devices, IUDs). While clinically, LARC have been proven safe and effective at preventing pregnancy \& decreasing menstrual symptoms, it is unclear what impact this type of contraceptive may have on physiological responses to extreme environments (heat, cold and high altitude). Additionally, iron deficiency and iron deficiency anemia are prevalent in U.S. military women which likely affect health and performance. There is evidence to suggest that the prevalence of iron deficiency and iron deficiency anemia is lower in women utilizing LARCs, which preserve iron stores, likely due to reduced menstrual blood loss that compounds with each cycle over the course of months. Due to the increasing interest in the utilization of LARCs it is important to understand what, if any, impact these methods of contraception may have on a female Soldier's physiological responses.
The overall goal of the present study is to characterize iron status and physiological responses (including but not limited to sweating, skin blood flow, ventilation, and heart rate) to extreme environmental stressors of heat, cold and high altitude (i.e. hypobaric hypoxia) in women utilizing LARCs. Up to thirty-three individuals (n=18 LARCs, n=15 monophasic oral contraceptives) will complete testing visits separated by at least 48 hours for environmental testing visits. During heat stress testing, measures of core body temperature, skin temperature, and sweat rate will be measured during a standardized protocol in hot, humid conditions. During cold stress, measures of body core temperature, metabolic heat production, skin blood flow and temperature (at both distal extremity and proximal body sites) will be assessed in order to better quantify the impact of exogenous sex hormones via LARCs and OCs in volunteers exposed to the cold. Measurements will be obtained during a standardized protocol in cold air (~90 min; 10°C). For altitude, cardiopulmonary responses will be assessed during rest and exercise during an acute altitude exposure (4300m). Blood samples will be collected throughout the investigation in order to quantify sex hormone concentrations, iron status, and inflammatory biomarkers in response to environmental stressors. The investigators will also utilize laboratory tests (i.e., carbon monoxide (CO) rebreathing technique) and collect blood samples to quantity iron stores in these groups of women. To characterize iron status, the Soldier Performance Health and Readiness (SPHERE) epidemiological data repository will be utilized to quantify the prevalence of iron deficiency and iron deficient anemia diagnoses between women using LARCs and women not utilizing LARCs.
- Conditions
- Contraception, Iron Deficiencies
- Being tested
- Blood volume and environmental testing
- Medical subject headings
- Iron Deficiencies
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Blood volume and environmental testingOther
Testing blood volume measures, iron stores, and physiological responses to acute environmental exposures of heat, cold, and high-altitude (each environment independently)
| Study group | Role | What they receive |
|---|---|---|
| SARC | Control group utilizing short-acting reversible contraceptives (i.e. combined oral contraceptives tested only in the active pill phase or transdermal patch) Receives: Other: Blood volume and environmental testing | |
| LARC users | Users of hormonal long-acting reversible contraceptives (LARCs) (e.g. hormonal IUDs, hormonal subcutaneous implants) Receives: Other: Blood volume and environmental testing |
What is being measured
The primary outcome is the main question the study is designed to answer.
Iron status
Iron stores as measured by ferritin levels
Measured: upon initial visit
Ventilation
ventilatory response to high altitude exposure at rest and during exercise
Measured: intermittently throughout high-altitude trial (5 timepoints overall over ~6-7 hours)
Thermoregulation in the heat - core temperature
Measure of core temperature
Measured: measured intermittently throughout trial (at least every 5 minutes) for 2 hour exposure
Thermoregulation in the cold - skin blood flow
Measure of thermoregulation during resting cold stress to include skin blood flow
Measured: measured intermittently throughout cold trial (at least every 5 minutes) for 2 hour exposure
Thermoregulation in the heat - skin temperature
Measured: measured intermittently throughout trial (at least every 5 minutes) for 2 hour exposure
Thermoregulation in the heat - sweating rate
Calculated from pre- and post-nude body mass corrected for fluid consumed and urine produced
Measured: Only measured during heat stress visit, at one timepoint immediately after exercise on heat stress visit (post-exercise, within 10-20 minutes)
Thermoregulation in the cold - core temperature
Measured: measured intermittently throughout cold trial (approximately every 5-10 min) for 2 hour exposure
Thermoregulation in the cold - skin blood flow
Measured: measured intermittently throughout cold trial (approximately every 5-10 minutes) for 2 hour exposure
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted3 Apr 2025
- Study start1 Nov 2024
- Primary completionSep 2027 (estimated)
- Study completionSep 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for ContraceptionStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Cohort
- Time perspective
- Cross-sectional
- Enrolment
- 33 participants (estimated)
Sponsor and investigators
- Lead sponsor
- United States Army Research Institute of Environmental Medicine
- Sponsor type
- US federal agency
- Responsible party
- Sponsor
- Investigators
- Gabrielle Giersch, PhD, Principal investigator, United States Army Research Institute of Environmental Medicine
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06909695
- Sponsor's protocol ID
- 24-19
- Status last verified
- Apr 2026
- First submitted
- 4 Oct 2024
- Last updated
- 30 Apr 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 30 Apr 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Influences of Long-acting Reversible Contraceptives on Iron Status and Physiological Responses to Extreme Environments in Women
- ClinicalTrials.gov ID
- NCT06909695
- Acronym / sponsor ID
- 24-19
- Conditions
- Contraception, Iron Deficiencies
- Study type
- Observational
- Recruitment status
- Recruiting
- Enrolment
- 33 participants (estimated)
- Lead sponsor
- United States Army Research Institute of Environmental MedicineUS federal agency
- Study start
- 1 Nov 2024 (actual)
- Primary completion
- Sep 2027 (estimated)
- Study completion
- Sep 2027 (estimated)
- First posted
- 3 Apr 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Over recent years, military service women have shown increasing interest in utilizing long-acting reversible contraceptives (LARCs; i.e., implants or intrauterine devices, IUDs). While clinically, LARC have been proven safe and effective at preventing pregnancy \& decreasing menstrual symptoms, it is unclear what impact this type of contraceptive may have on physiological responses to extreme environments (heat, cold and high altitude). Additionally, iron deficiency and iron deficiency anemia are prevalent in U.S. military women which likely affect health and performance. There is evidence to suggest that the prevalence of iron deficiency and iron deficiency anemia is lower in women utilizing LARCs, which preserve iron stores, likely due to reduced menstrual blood loss that compounds with each cycle over the course of months. Due to the increasing interest in the utilization of LARCs it is important to understand what, if any, impact these methods of contraception may have on a female Soldier's physiological responses.
The overall goal of the present study is to characterize iron status and physiological responses (including but not limited to sweating, skin blood flow, ventilation, and heart rate) to extreme environmental stressors of heat, cold and high altitude (i.e. hypobaric hypoxia) in women utilizing LARCs. Up to thirty-three individuals (n=18 LARCs, n=15 monophasic oral contraceptives) will complete testing visits separated by at least 48 hours for environmental testing visits. During heat stress testing, measures of core body temperature, skin temperature, and sweat rate will be measured during a standardized protocol in hot, humid conditions. During cold stress, measures of body core temperature, metabolic heat production, skin blood flow and temperature (at both distal extremity and proximal body sites) will be assessed in order to better quantify the impact of exogenous sex hormones via LARCs and OCs in volunteers exposed to the cold. Measurements will be obtained during a standardized protocol in cold air (~90 min; 10°C). For altitude, cardiopulmonary responses will be assessed during rest and exercise during an acute altitude exposure (4300m). Blood samples will be collected throughout the investigation in order to quantify sex hormone concentrations, iron status, and inflammatory biomarkers in response to environmental stressors. The investigators will also utilize laboratory tests (i.e., carbon monoxide (CO) rebreathing technique) and collect blood samples to quantity iron stores in these groups of women. To characterize iron status, the Soldier Performance Health and Readiness (SPHERE) epidemiological data repository will be utilized to quantify the prevalence of iron deficiency and iron deficient anemia diagnoses between women using LARCs and women not utilizing LARCs.
Study design
- Observational model
- Cohort
- Time perspective
- Cross-sectional
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| SARC | – | Other: Blood volume and environmental testingControl group utilizing short-acting reversible contraceptives (i.e. combined oral contraceptives tested only in the active pill phase or transdermal patch) |
| LARC users | – | Other: Blood volume and environmental testingUsers of hormonal long-acting reversible contraceptives (LARCs) (e.g. hormonal IUDs, hormonal subcutaneous implants) |
Who may qualify
- Ages
- 18 to 40 years
- Sex
- Female only
- Healthy volunteers
- Accepted
- Age groups
- Adult
- Study population
- The proposed population will be healthy and active women between the ages of 18-40. This population is suitable for the purpose of this investigation since they are the most militarily relevant population (i.e., representative of the U.S. Army active duty population).
Key inclusion criteria (9 listed)
- • Females, age 18-40 y
Key exclusion criteria (24 listed)
- • Females who are pregnant, planning to become pregnant during the study, or breastfeeding.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Blood volume and environmental testingTesting blood volume measures, iron stores, and physiological responses to acute environmental exposures of heat, cold, and high-altitude (each environment independently) | Other | LARC users, SARC |
Primary outcome
Iron status
Time frame: upon initial visit
Iron stores as measured by ferritin levels
Ventilation
Time frame: intermittently throughout high-altitude trial (5 timepoints overall over ~6-7 hours)
ventilatory response to high altitude exposure at rest and during exercise
Thermoregulation in the heat - core temperature
Time frame: measured intermittently throughout trial (at least every 5 minutes) for 2 hour exposure
Measure of core temperature
Thermoregulation in the cold - skin blood flow
Time frame: measured intermittently throughout cold trial (at least every 5 minutes) for 2 hour exposure
Measure of thermoregulation during resting cold stress to include skin blood flow
Thermoregulation in the heat - skin temperature
Time frame: measured intermittently throughout trial (at least every 5 minutes) for 2 hour exposure
Thermoregulation in the heat - sweating rate
Time frame: Only measured during heat stress visit, at one timepoint immediately after exercise on heat stress visit (post-exercise, within 10-20 minutes)
Calculated from pre- and post-nude body mass corrected for fluid consumed and urine produced
Thermoregulation in the cold - core temperature
Time frame: measured intermittently throughout cold trial (approximately every 5-10 min) for 2 hour exposure
Thermoregulation in the cold - skin blood flow
Time frame: measured intermittently throughout cold trial (approximately every 5-10 minutes) for 2 hour exposure
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 30 Apr 2026.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Gabrielle Giersch, PhD principal investigator
United States Army Research Institute of Environmental Medicine
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Contraception and Iron Deficiencies, run by United States Army Research Institute of Environmental Medicine at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 9 inclusion and 24 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 30 Apr 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Gabrielle E Giersch, PhD (508-206-2421, gabrielle.e.giersch.civ@health.mil), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Iron status (time frame: upon initial visit). The study lists 8 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 30 Apr 2026.