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Venous Thromboembolism Risk in Women Using Levonorgestrel and Other Hormonal Contraceptives

Verified siteRegistered drugNo placebo
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What is this trial about?

A plain-language summary of the goals, design and what participants do

The study focuses on women who use hormonal contraceptives, which are medicines that prevent pregnancy. The contraceptives being examined contain one or more of the following active ingredients: levonorgestrel, desogestrel, ethinylestradiol, drospirenone, estradiol hemihydrate, estetrol, and nomegestrol acetate. These products are taken by mouth or placed inside the uterus, and they work by delivering hormones that stop ovulation. The health condition of interest is the risk of developing blood clots in the veins, known as Venous Thromboembolism, which can be increased by certain hormone formulations.

The purpose of the study is to assess how different contraceptive formulas affect the body’s tendency to form clots. Participants will provide blood samples at several visits, and the samples will be tested to measure thrombin generation, a process that shows how quickly blood can clot. The main laboratory test used is calibrated automated thrombography, which gives a detailed picture of clotting activity. By comparing results from women using each type of contraceptive with those who do not use hormonal methods, researchers hope to identify lifestyle factors that can be changed to lower clot‑formation risk.

The research process

The trial runs in 6 steps – from screening to follow-up. Each step says what happens and what the team monitors.

  1. Step 1

    Enrollment and consent

    After joining the study you will be asked to read information about the research and sign a consent form that confirms your voluntary participation.

    The consent process includes an explanation of the purpose of the study, the procedures you will undergo, and the possible risks and benefits.

  2. Step 2

    Baseline assessment

    During the first visit you will complete a questionnaire about lifestyle factors that can affect blood clot risk, such as smoking, physical activity, and body weight.

    A blood sample will be drawn to measure thrombin generation and other laboratory parameters before starting any study medication.

  3. Step 3

    Start of hormonal contraceptive

    You will receive one oral hormonal contraceptive that is assigned by the study. the possible products and their daily doses are:

    levonorgestrel 150 µg taken once daily,

    desogestrel 75 mg taken once daily,

    ethinylestradiol 30 µg taken once daily (often combined with other hormones),

    drospirenone 3 mg or 4 mg taken once daily,

    estradiol hemihydrate 1.5 mg taken once daily,

    estetrol 14.2 mg taken once daily,

    nomegestrol acetate 2.5 mg taken once daily,

    levonorgestrel intrauterine device 20 µg or 14 µg released locally (if assigned to an intrauterine system).

    The medication is taken by mouth unless an intrauterine device is assigned, in which case it is placed by a qualified professional and does not require daily dosing.

  4. Step 4

    Daily medication intake

    If you receive an oral product, you will take the tablet at the same time each day, preferably with or without food as you are instructed.

    The medication will be continued for the entire study period, which may last several months up to the end of the study.

  5. Step 5

    Scheduled follow‑up visits

    You will attend follow‑up visits that are scheduled by the study team. at each visit a new blood sample will be collected to evaluate thrombin generation, the normalized activated protein c sensitivity ratio (nAPCsr), and other routine laboratory tests.

    You will also be asked to update information about any changes in lifestyle, medication use, or health status that could influence clot risk.

  6. Step 6

    Final visit and study completion

    At the last visit you will provide a final blood sample and complete a concluding questionnaire about your experience and any changes in risk factors.

    The collected data will be used to compare the clotting profiles of different hormonal contraceptive groups with those of non‑users.

Who can join the trial?

3 criteria

  • Age: Women who are between 18 and 40 years old.
  • Hormonal contraceptive use: Currently using hormonal birth control (pills, patch, ring, or injection) for at least three months, or not using any hormonal birth control for at least three months if you are in the control group.
  • Signed informed consent: You must read and sign a document that explains the study and shows that you agree to take part.

Who cannot join the trial?

9 criteria

  • Having a past history of blood clots in veins or arteries (venous/arterial thromboembolic disorders) – these are conditions where clots block blood flow.
  • Having a past history of unexplained bleeding or a condition called hemophilia, which means the blood does not clot properly.
  • Currently using medicines that thin the blood, such as anticoagulants, antiplatelet drugs, or NSAIDs (common pain relievers like ibuprofen) within the last 10 days.
  • Being pregnant or breastfeeding.
  • Having any cancer (malignant disease) diagnosed within the past 5 years.
  • Having an autoimmune disease that can raise clot risk, such as inflammatory bowel disease or systemic lupus erythematosus (SLE).
  • Having a recent acute infection or inflammation, including illnesses like COVID‑19, the flu, or RSV (a common respiratory virus).
  • Having serious long‑term kidney or liver problems (chronic kidney/liver disease).
  • Having undergone major surgery (an operation requiring a hospital stay) within the past 3 months.
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Investigated drugs

  • Levonorgestrel (oral)

    is a synthetic hormone used in many birth‑control pills. In this trial it is given as a single pill taken by mouth to prevent pregnancy. Researchers are looking at how this hormone may affect the blood’s tendency to form clots, since some hormonal contraceptives can change clotting factors.

  • Desogestrel

    is another synthetic hormone that is taken by mouth in birth‑control pills. The study includes women using desogestrel to see whether this progestin influences thrombin generation and the risk of developing blood clots compared with other contraceptives.

  • Ethinylestradiol (oral)

    is a synthetic form of estrogen that is commonly combined with a progestin in combined oral contraceptives. Participants taking ethinylestradiol alone are being evaluated to understand how estrogen by itself may change clotting activity and contribute to thrombosis risk.

  • Drospirenone

    is a synthetic progestin taken as a daily oral tablet. It is often used in combined contraceptives with estrogen. In the trial, women using drospirenone are monitored to determine its specific impact on blood clot formation and whether it poses a higher or lower risk than other progestins.

  • Estradiol hemihydrate

    is a form of natural estrogen given as an oral tablet. The study includes this medication to compare how a more physiological estrogen affects thrombin generation versus synthetic estrogens used in other contraceptives.

  • Estetrol

    is a newer, naturally occurring estrogen that is taken by mouth. Researchers are testing whether this newer estrogen has a different effect on clotting factors and overall thrombosis risk compared with older estrogen compounds.

What is already known about the treatment

  • Levonorgestrel

    This synthetic hormone is taken either as a daily oral tablet (150 µg) or placed inside the uterus as an intrauterine device (20 µg or 14 µg). It is an approved and widely used progestin for preventing pregnancy and for emergency contraception. It works by binding to progesterone receptors, stopping the release of an egg and thickening cervical mucus to block sperm. It belongs to the class of hormonal contraceptives called progestins.

  • Desogestrel

    Desogestrel is taken as an oral tablet (75 mg) and is a prescription medication approved for birth control. It is a modern progestin used in combined or progestin‑only pills. It blocks ovulation by activating progesterone receptors, which also makes cervical mucus thicker. It is classified as a progestin, a type of hormonal contraceptive.

  • Ethinylestradiol

    Ethinylestradiol is an oral estrogen taken in low doses (0.02–30 µg) and also appears in combination tablets such as coated tablets (75 µg). It is an approved component of many combined oral contraceptives. It works by binding to estrogen receptors, helping to regulate the menstrual cycle and supporting the progestin’s effect on preventing ovulation. It is classified as a synthetic estrogen in hormonal contraceptives.

  • Drospirenone

    Drospirenone is taken as an oral tablet (3–4 mg) and is a prescription component of combined birth‑control pills. It is an approved progestin that also has mild anti‑aldosterone activity. It binds to progesterone receptors to stop ovulation and also reduces water retention, which can lower blood pressure. It belongs to the progestin class of hormonal contraceptives.

  • Estradiol hemihydrate

    This form of estradiol is taken orally (1.5 mg) and is an approved estrogen used for hormone replacement therapy and sometimes in contraceptive combos. It works by attaching to estrogen receptors, helping to restore normal hormone levels and support the uterine lining. It is classified as a natural estrogen medication.

  • Estetrol

    Estetrol is taken as an oral tablet (14.2 mg) and is a newer, approved estrogen used in some combined contraceptive pills. It binds to estrogen receptors but produces a milder effect, providing contraceptive benefit with potentially fewer side effects. It helps regulate the menstrual cycle and works together with a progestin to stop ovulation. It is classified as a synthetic estrogen in hormonal contraceptives.

Investigated diseases

Venous thromboembolism risk associated with hormonal contraceptives - This condition involves the formation of blood clots in the deep veins, most often in the legs, which can grow larger or break loose. When a clot travels to the lungs, it can cause a blockage in the pulmonary arteries. The risk increases with certain hormonal contraceptive formulations that affect clotting factors. Over time, repeated clot formation can lead to persistent vein damage and reduced blood flow. The condition may evolve from isolated leg vein clots to more widespread clotting events if underlying risk factors are not managed.
Trial detailsLast updated 9 Oct 2026
Age18+ yearsPhasePhase IIITrial ID2026-527084-15-00Estimated enrolment350 patientsSponsorUniversity Of Debrecen

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