Contraception study in women: comparing oral drospirenone‑only, drospirenone + ethinylestradiol, and drospirenone + estetrol tablets

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What is this study about?

The trial looks at women who need birth control, called contraception, and compares three oral pill formulations. One pill contains the hormone drospirenone together with the newer estrogen estetrol, another combines drospirenone with the traditional estrogen ethinylestradiol, and a third contains only drospirenone without any estrogen.

The main purpose is to see whether the pill with estetrol and drospirenone has a smaller effect on blood clotting, measured by a laboratory test called endogenous thrombin potential, compared with the pill that uses ethinylestradiol and drospirenone, while the drospirenone‑only pill is expected to have little impact on clotting.

Participants will be assigned to take one of the three pills every day for about a year. They will attend routine visits, and at the end of the 12‑month period they will have a final check to assess how the medication affected the body. No additional procedures beyond the regular pill use and scheduled visits are required.

1 first study visit

after joining, attend the initial study visit where personal health information is recorded and basic laboratory tests are performed.

during this visit, the study medication is assigned randomly to one of three groups.

2 receive study medication

if assigned to the drspirenone‑only group, receive slinda 8 mg tablets containing only drospirenone.

if assigned to the e4+drspirenone group, receive drovelis tablets that contain 3 mg drospirenone and 14.2 mg estetrol.

if assigned to the ee20µg+drspirenone group, receive daylette tablets that contain 3 mg drospirenone and 0.02 mg ethinylestradiol.

each tablet is taken by mouth once daily, preferably at the same time each day.

3 daily medication intake

swallow one tablet with water; no food restrictions are required.

continue taking the assigned tablet every day for the entire 12‑month study period.

4 regular follow‑up visits

schedule visits at approximately 1 month, 3 months, 6 months, and 12 months after the first visit.

at each visit, report any side effects, undergo brief physical examinations, and provide blood samples for laboratory analysis.

the purpose of these visits is to monitor safety, assess how the medication affects blood clotting factors, and collect other health data.

5 final 12‑month visit

after one year of daily tablet use, attend the endpoint visit.

the final visit includes a comprehensive health assessment, laboratory tests to evaluate coagulation, and collection of study questionnaires.

after this visit, no further study medication is required.

Who Can Join the Study?

Be a woman aged between 18 and 40 years when you join the study.
Agree to take the study medication and sign a written consent form that explains the research.
Have a body‑mass index (BMI) between 18 and 29.9. BMI is a measure that compares your weight to your height.
Be in good health, meaning you do not have any serious illnesses diagnosed by a doctor and you are not taking any ongoing medical treatments.
Have a regular menstrual cycle, which means your periods occur about the same way each month.
Wait at least two months after stopping any hormonal birth‑control pills or devices before starting the study medication.
Be at least three months past a pregnancy or breastfeeding period.
Be able to read and understand Finnish well enough to follow the study documents and talk with the study staff.

Who Cannot Join the Study?

Having a medical reason that makes using combined contraceptives unsafe (a “contraindication” means a condition that says you should not use that medication).
Having important problems found in the initial health tests or in an ultrasound picture (the ultrasound is a scan that uses sound waves to look at internal organs).
Smoking cigarettes or other nicotine products, using illegal (illicit) drugs, or drinking alcohol in a way that could be harmful (these habits can affect study results).
Planning to become pregnant while the study is happening (the study is not designed for people who want to get pregnant).
Having any other disease or health condition that could interfere with how the study is done or how the results are understood.

Where you can join this trial?

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Verified Sites

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Other Sites

Site Name	City	Country	Status
Oulu University Hospital	Oulu	Finland
Hfsfxzvw Uwqqaiiimp Cnzyvuj Hcxztkjc	Helsinki	Finland

Trial status

Country	Status	Recruitment Start
Finland	Not yet recruiting	01.02.2026

Trial locations

Investigated drugs:

Slinda is a birth control pill that contains only the hormone drospirenone. In this study it is used as the comparison group so researchers can see how a pill with drospirenone alone affects blood clotting tests. The goal is to understand the baseline effect of drospirenone without any added estrogen.

Drovelis is a combined oral contraceptive that includes drospirenone plus a newer type of estrogen called estetrol. This medication is one of the test groups. Researchers are looking at whether the combination of drospirenone with estetrol has a smaller impact on blood clotting than the traditional estrogen‑containing pill.

Daylette is another combined birth control pill that contains drospirenone together with the more common estrogen ethinylestradiol. It is also a test group in the trial. The study compares this standard combination to the estetrol‑based pill and to drospirenone alone to see how each affects clotting measures.

Contraception – Contraception is the intentional prevention of pregnancy using various methods. It works by stopping the release of an egg, blocking sperm, or creating an environment that does not support fertilization. Over months of regular use, the chosen method continues to suppress the chance of conception as long as it is correctly applied. When a method is stopped, fertility typically returns to its previous state within a few weeks to several months, depending on the type used. The effectiveness of contraception can change if the method is missed, damaged, or interfered with by other substances.

Trial ID:

2025-523359-71-00

Protocol code:

CoCo3

Trial Phase:

Therapeutic confirmatory (Phase III)

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Contraception study in women: comparing oral drospirenone‑only, drospirenone + ethinylestradiol, and drospirenone + estetrol tablets

What is this study about?

Who Can Join the Study?

Who Cannot Join the Study?