Birth control with up to 92% lower hormone doses could still be effective

Doctors often prescribe hormonal contraceptives to female patients who are trying to prevent pregnancy. According to the Centers for Disease Control and Prevention (CDC), in the United States, 12.6% of females aged 15 to 49 years use an oral contraceptive, and 10.3% of women use long-acting reversible contraceptives.

Hormonal contraceptive devices work by using synthetic hormones, such as estrogen and progesterone, to prevent pregnancy.

They can work in multiple ways, including stopping ovulation or causing the uterine lining to thin so that an implanted egg cannot attach.

A few types of hormonal contraceptives include pills, which can be a combination pill or progestin-only, the arm implant (Nexplanon), the contraceptive patch (Xulane), and intrauterine devices or IUDs (Mirena or Skyla).

In addition to prescribing contraceptives to prevent pregnancy, sometimes doctors will prescribe them to help those with polycystic ovary syndrome (PCOS) to reduce the size of cysts and thereby reduce pain, or in the treatment of endometriosis, to help control pain and excessive bleeding.

Hormonal contraceptives can have some side effects that range from mild to severe:

Also, those who smoke while taking hormonal contraceptives have an increased risk of deep vein thromboembolism, which refers to blood clots in the leg.

Some milder side effects may go away, but individuals should discuss side effects with their healthcare providers to determine the safest way to proceed.

The researchers conducting the current study wanted to expand on previous contraceptive research, and analyze whether lower hormone doses could still be effective in preventing pregnancy.

Not only did they consider reducing the amount of hormones in the contraceptives, but they also theorized that it is possible to adjust the timing of different dosages to receive maximum benefit.

“The objective is to identify strategies to understand when and how much estrogen and/ or progesterone to administer to obtain a contraceptive state,” write the authors.

The scientists studied data from 23 female participants aged 20 to 34 years. According to the researchers, the participants had regular menstrual cycles that lasted from 25 to 35 days.

They ran their data on two models: the pituitary model and the ovarian model.

The pituitary gland is part of the endocrine system, which regulates hormones that impact ovulation. With the pituitary model, they analyzed the timing of the release of ovulation hormones as well as the hormone levels.

With the ovarian computer model, the scientists looked at how the ovaries responded to the hormones released.

Additionally, the researchers ran models to see how different levels of estrogen and progesterone affected the menstrual cycle.

The computer models showed that it is possible to make adjustments to the hormone dosage and prevent ovulation.

Not only did the models show that hormones could be reduced, but the researchers also found that it is possible to focus on adjusting the dose during certain parts of the cycle and still have the contraceptives be effective.

With estrogen-only contraceptives, the scientists reduced the dosage by 92% and retained effectiveness. In progesterone-only contraceptives, they reduced the dose by 43% and still had contraceptive benefits.

As far as the timing of the hormone delivery goes, the authors note “that it is most effective to deliver the estrogen contraceptive in the mid-follicular phase.”

Study author Brenda Gavina, a doctoral researcher at the University of the Philippines Diliman, spoke with Medical News Today about the study and further explained the results. She told us:

“It was surprising that theoretically, our mathematical model — with the simplifying assumptions — showed that as low as 10% of the total exogenous estrogen dose in constant administration could achieve contraception as long as this dosage is perfectly timed.”

“Lower doses reduce risks of adverse side effects such as thrombosis and myocardial infarction associated with large doses,” noted Gavina.

The researcher also explained that “the current mathematical model does not capture all factors in contraception since the reproductive function in women is a very complex multiscale dynamical system.” She believes that, as more data comes out “it can be refined to address other contraception issues.”

While the study results show that adjusting the hormone dose in contraceptives is possible while maintaining efficacy, the study is not at the point of having clinical use yet, which is something experts that spoke with MNT emphasized.

“It’s important to realize that this [study finding] is theoretical and was not tested in humans,” commented Dr. Sophia Yen, a clinical associate professor at Stanford Medical School, and the co-founder and CEO of Pandia Health in Sunnyvale, CA, not involved in the current study.

Dr. Yen also cautioned that “[the hormone level reduction] most likely won’t be so great for those with higher BMIs because of the greater volume of distribution for the drugs.”

Dr. Sandra Hurtado, assistant professor of obstetrics, gynecology, and reproductive sciences at McGovern Medical School at UTHealth Houston, not involved in the study, also spoke with MNT about its findings.

Dr. Hurtado emphasized that the study is a mathematical model that needs to “undergo testing in an animal model and in humans to be able to test its safety and efficacy.”

However, she did see potential in the study. “If there was a way to test and record the hormone levels in each individual and be able to give that person the dose at the correct time, that would be ideal,” commented Dr. Hurtado.

She further suggested that taking this research further developing something like an automated insulin delivery system could be helpful. “At this time those are costly and not justifiable for contraceptive use, but with continued advancing technology and decrease in cost of electronics, hopefully, it can be developed in the near future.”