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  • A new study shows the dosage of hormones in birth control pills can be reduced by as much as 92% and still prevent ovulation.
  • As low as 10% of the total exogenous estrogen dose in constant administration could achieve contraception as long as this dosage is perfectly timed.
  • Experts recommend reducing the dosage of hormonal birth control for safer contraception.

According to a new study, published in PLOS Computational Biology, hormone dosage in birth control pills often taken as birth control pills could be lowered by as much as 92% and still successfully block ovulation.

For the study, researchers analyzed hormone levels in 23 women aged 20 to 34 with normal menstrual cycles. They constructed a model which showed the interactions between numerous hormone levels and the effect of exogenous hormones.

During a menstrual cycle, there are four phases: the menses phase (when the lining of the uterus sheds), the follicular phase (when estrogen levels go up causing the uterus lining to thicken), ovulation (when an egg is released) and the luteal phase (when the egg travels to the uterus).

Hormones play an important role during each phase. For example, in order for ovulation to occur, estrogen levels need to go up.

In most contraceptives, exogenous estrogen and/or progesterone is used to prevent ovulation.

The model suggested that to suppress ovulation it is possible to reduce the total hormonal dose by 92% in birth control pills that contain only estrogen, or the total dose by 43% in birth control pills that contain only progesterone.

“An interesting result of our study is the suggestion that compared to the administration of constant dosage (which is how most contraceptive pills are administered), a continuous infusion with varying doses (contraceptive implants and patches are some ways to administer exogenous estrogen/progesterone continuously), a total dosage of which is significantly lower than that of constant dose administration, may still effectively suppress ovulation,” Brenda Lyn A. Gavina, PhD student at the University of the Philippines Diliman, told Healthline.

Oral birth control pills are usually composed of estradiol and progestin.

“Lowering the estradiol dose can increase breakthrough bleeding, efficacy in obese women, but decrease the risk of blood clotting,” said Dr. Monte Swarup, FACOG, board-certified OB/GYN and founder of HPV HUB. “Estradiol increases proteins through its metabolism in the liver including clotting proteins.”

There are many benefits to lowering the hormonal dosage to the lowest effective dose.

“This reduces potential risks for both complications and side effects,” Dr. Pamela Berens, professor of obstetrics, gynecology, and reproductive sciences with McGovern Medical School at UTHealth Houston told Healthline. “Some serious complications of higher hormonal doses in contraception include things like blood clots (both deep venous clots in legs for example and clots that impact the lung such as pulmonary embolism).”

Additional clot risks include rare complications such as heart attack, pulmonary embolism, and stroke. By lowering the hormonal dosage the risks of these rare but serious complications are also reduced.

More common side effects such as nausea, breast tenderness, bloating and irritability are also less likely with lower hormonal doses. Over the years the hormonal doses in commonly used birth control have been lowered while maintaining the effectiveness, Berens added.

In the study, the model also showed the importance of timing the hormones during the cycle.

“Specifically, 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 (the timing was also shown in our optimization result),” Gavina stated.

However, it’s important to note, “the results of this study are not directly translatable to actual patients, but the principles proposed in our study could easily be translated,” Gavina explained. “We hope these results aid clinicians in identifying the most favorable dose and treatment schedule for contraception to achieve the most effective and efficient drug use.”

Furthermore, timing the hormones helps control the amount of bleeding.

“In hormone replacement therapy during perimenopause, timing the hormones with the cycles decreases breakthrough or irregular bleeding,” Swarup stated.

Oral birth control pills are very safe and commonly used, but increase blood clotting risk. Choosing a contraceptive can be complex incorporating the patient’s medical history, goals, age, etc. It is best that is discussed on an individual basis with a patient’s provider, Swarup added.

IUDs are very safe with or without progesterone. Progestin implants and Depot Provera are very safe but can cause weight gain and irregular bleeding, Swarup explained.

Using contraceptives that do not have hormone but utilize barrier methods such as condoms are the safest options in terms of other side effects.

“Through the years, safer contraception has been achieved by reducing the dosage of hormonal contraceptives,” said Gavina. “Significantly reducing the dosage would alleviate side effects like thrombosis and myocardial infarction. Our study suggests a method on how ovulation can be suppressed. When more data become available, our mathematical model could be coupled with a pharmacokinetics model to obtain patient-specific dosing schemes.”

Berens explained there are some risk factors (such as age, smoking, migraines, hypertension, obesity, clotting disorders and many others) that may influence the safety and effectiveness of various birth control options.

In addition, some women prefer regular cycles while others may prefer less frequent and lighter bleeding that is less predictable. Some methods may require regular intervention (such as taking a daily pill) while others such as the IUD require an office procedure for insertion but then are effective for an extended period of time.

There are many different options for contraception (pills, shots, vaginal rings, patches, implants and intrauterine devices).

Lastly, there are potential non-contraceptive benefits (such as improving acne or protecting against heavy cycles) that differ between various birth control options. All choices come with different pluses and minuses. It is important that the patient and the provider review both the specific health conditions that can impact risks of various contraceptive methods but also the patient’s desires, Berens stated.

According to new research, hormonal dosage in birth control pills can be lowered by as much as 92% and still suppress ovulation.

Another interesting finding is that as low as 10% of the total exogenous estrogen dose in constant administration could result in contraception as long as this dosage is timed correctly.

For the safest contraception, experts recommend reducing the dosage of hormonal contraceptives.