According to a study (hereafter referred to as Gavina et al.) from the University of the Philippines Diliman, the amount of estrogen currently in hormonal birth control pills is higher than it needs to be in order to effectively prevent ovulation (and, therefore, pregnancy) [1]. This is welcome news for millions of Pill users who are at risk of multiple side effects, some serious, because of the synthetic estrogen in their hormonal birth control. Although the amount of estrogen in the Pill has drastically decreased over time, many women still notice a plethora of estrogen-related side effects from their contraception [2]. Some effects, such as thrombosis (blood clots) or cancer, can even be life-threatening.
Estrogen side effects drove researchers to study lowering the dose
Gavina et al. cited the side effects of estrogen as a driving force behind their research. They hoped to find that a lowered amount of estrogen could still effectively prevent pregnancy. They reanalyzed menstrual cycle data collected from 23 women aged 20 to 34 years old that was collected during a previous study done by other researchers. That study measured Estrogen (E2), Progesterone (P4), Luteinizing Hormone (LH), Follicle Stimulating Hormone (FSH), and inhibin levels via blood draws.
Gavina et al. devised a complex mathematical model which calculated the minimum estrogen (and progestin) dosage needed to prevent ovulation. Their model also determined the optimal cycle day to take the synthetic hormones found in the Pill.
Takeaways
Gavina et al. found that administering a very short and small dose of estrogen during the mid-follicular phase was most effective and greatly minimized the amount of estrogen needed to stop ovulation. On this protocol, a woman would take estrogen-containing birth control around day 7 of her cycle. With this approach, researchers discovered that estrogen mono-therapy (birth control only containing synthetic estrogen) could contain up to 92% less estrogen, and progestin-only birth control could contain 43% less progestin. The Pill, which contains both synthetic estrogen and progestin, could have even lower amounts of both. A woman would no longer receive a one-size-fits-all dosage of synthetic hormones day after day. Instead she would receive one small dose timed to her unique cycle.
Will this study lead to estrogen dosage changes in the Pill?
However, this does not mean that the way the Pill is made is about to change dramatically. According to the study itself, this is the first time that optimal control dosages have been tested for contraceptives. Multiple problems limit the practicality and usability of this new research.
The study didn’t enroll animal or human participants
A major limitation on this study is the fact that it did not study the effects of timed estrogen dosages on actual animal or human participants. Instead it used data from participant cycles and ran it through a computer model to predict ovulatory response. Computer models can be very reliable for simulating real world impacts in economics, engineering, and more. But whether they will be accurate in this area is a big question mark.
Many women don’t have a 28-day cycle like the researchers’ mathematical model assumed
Another study limitation is the use of a 28-day cycle. While 28 days is the average length of the female reproductive cycle, most women do not have a 28 day cycle [3]. A more detailed study would have to vary the length of participant cycles in order to truly understand the effects of giving a timed dosage of birth control versus the standard sustained usage of the Pill. Other experts agree that further studying on actual human participants would be necessary, as hormone levels vary from woman to woman.
The researchers’ math model works for just four cycles in a row
Gavina et al. contended that their model only works for four consecutive cycles. This is because stopping ovulation in one cycle will change the hormone levels of the next, thus altering when the timed dosage of birth control would need to be administered over time.
Women on this protocol would likely need to change the day they take the drug in accordance with their change in hormone levels, which could only be determined with a blood sample. This would require women to be blood tested on a regular basis, or risk taking their medication on the incorrect day and forfeiting the pregnancy prevention effectiveness.
The researchers stipulated that a device would be necessary to constantly monitor a woman’s hormonal levels via blood samples and administer the correct dosages of birth control at the proper time in her cycle. This is similar to how insulin pumps work for Type I diabetics, but it may not appeal to many women.
The bottom line
Much more research is needed to determine whether or not it is viable to drastically decrease the amount of estrogen in birth control. Luckily, women who wish to avoid the negative side effects of synthetic estrogen have another option. The Gavina et al. study inadvertently supported the use of FAMs in two ways. First, to use the lowered-estrogen birth control, a woman would have to know where she was in her cycle. This is knowledge that use of a FAM would give her, though the study authors believe regular blood testing (sort of like how an insulin pump constantly monitors blood sugar levels) would be necessary.
The study also showed how the Pill is a one-size-fits-all or sledgehammer synthetic hormone approach, irrespective of any one woman’s needs. In other words, it’s true that women do not need to constantly suppress their fertility, because they are only fertile for a short window of time each month! Fertility Awareness Methods (FAM) allow individual women to monitor their cycles in a natural way that does not involve added hormones or regular blood testing, and instead works with observed biomarkers of fertility, so women can identify this window for themselves and act accordingly, based on their desire to avoid or achieve pregnancy.
Regardless of whether or not we could see a reduced-estrogen Pill, FAM will always offer women an effective, informative family planning option free from synthetic hormones and their side effects.
References:
[1] Gavina, Brenda Lyn A et al. “Toward an optimal contraception dosing strategy.” PLoS computational biology vol. 19,4 e1010073. 13 Apr. 2023, doi:10.1371/journal.pcbi.1010073 [2] Liao PV, Dollin J. Half a century of the oral contraceptive pill: historical review and view to the future. Can Fam Physician. 2012 Dec;58(12):e757-60. PMID: 23242907; PMCID: PMC3520685. [3] Grieger JA, Norman RJ. Menstrual Cycle Length and Patterns in a Global Cohort of Women Using a Mobile Phone App: Retrospective Cohort Study. J Med Internet Res. 2020 Jun 24;22(6):e17109. doi: 10.2196/17109. PMID: 32442161; PMCID: PMC7381001.Additional Reading:
Getting to know synthetic estrogens and progestins: What do they do to our bodies?
