Thumbs Up for New Birth Control Pill Across Multiple Subgroups

A new combined hormonal contraceptive pill was found to be effective across a wide range of patients, according to data from a phase III trial.

Estetrol/drospirenone (Nextstellis) had high contraceptive efficacy regardless of age group, body mass index (BMI), or prior contraceptive use, reported Mitchell Creinin, MD, of the University of California Davis in Sacramento.

Additionally, unscheduled bleeding occurred in less than a quarter of women, and decreased over time, he said in a presentation at the American College of Obstetricians and Gynecologists (ACOG) virtual meeting.

Estetrol (E4) is a native estrogen produced by the human fetal liver. Its unique characteristics result in selective activity in tissue, and in combination with drospirenone, it suppresses ovulation while having minimal impact on hormone-binding globulins, lipids, endocrine parameters, and hemostatic parameters.

Since estetrol is a new estrogen, these results confirm its ability to prevent pregnancy. For the study, researchers used the Pearl Index, which is defined as the number of pregnancies that occur with the use of one method per 100 women over a year.

"The Pearl Index is low no matter how you look at it," Creinin told MedPage Today, noting that he was "pleased that the data around BMI really showed no difference at all."

The combination pill was recently approved by the FDA for oral contraception, making it the first new estrogen to earn government approval in the last 50 years.

The researchers conducted a multicenter, open-label, phase III trial of more than 2,100 women (ages 16-50) in the U.S. and Canada.

In a subset of participants age 35 and younger, contraceptive efficacy was evaluated over 13 consecutive menstrual cycles. Subgroup analyses were performed based on age, BMI, and contraceptive use (whether participants switched from another contraceptive within the past 3 months or never used a contraceptive).

Participants were an average age of 26, about 70% were white, about 20% were Black, and around a quarter had a BMI over 30.

Contraceptive efficacy was similar across age groups: among women ages 16-25, the Pearl Index was 3.07 (95% CI 1.68-1.54) compared with 2.29 (95% CI 1.18-3.99) for women ages 26-35.

Additionally, there was no association between contraceptive efficacy and BMI, as women with a lower BMI (<30) had a Pearl Index of 2.57 (95% CI 1.57-3.97) compared with 2.94 (95% CI 1.08-6.41) among women with a higher BMI (>30).

For women who switched from a different birth control method, the Pearl Index was 2.13 (95% CI 1.02-3.92), compared with 3.12 (95% CI 1.78-5.06) for women who started the pill after no prior contraceptive use.

Regarding the data on unscheduled bleeding, Creinin said that most complaints were due to spotting, which did not require sanitary protection.

Unscheduled bleeding and spotting decreased over time, with less than 25% of women having irregular bleeding after using the pill for five consecutive cycles. Additionally, there were no clinically meaningful differences in bleeding based on age, BMI, or prior contraceptive use.

Creinin stated that the trial discontinuation rate due to bleeding was only 2.2%.

These findings "help show that this is a really great combination pill, and that the estrogen is really balancing out the effects of the progestin since participants had regular bleeding patterns," said Creinin.