The synthetic hormones in birth control pills may affect mental health, research suggests. sandoclr/Getty Images The combined hormonal contraceptive pill is the second most popular form of contraception in the United States, besides condoms.
Ethinyl estradiol has been used in the contraceptive pill since it was first created 60 years ago.
Researchers have discovered that rats given this hormone exhibited more behaviors associated with anxiety, compared to a more natural estrogen used in a more modern form of the contraceptive pill.
Rats given synthetic estrogens used in birth control pills exhibited greater signs of anxiety than those given natural estrogens, researchers have found.
The study showed synthetic estrogens were associated with lower steroid hormone levels when compared to natural ones. The findings, which are not yet published in a peer-reviewed scientific journal, were recently presented at ENDO 2024, the Endocrine Society’s annual meeting in Boston, MA.
The natural estrogen used in this study was similar to the one used in NOMAC-E2, a combined oral contraceptive formulation known as Zoely , which is produced by the pharmaceutical company Merck. The synthetic estrogen used in most combined hormonal contraceptive pills on the market is a highly potent synthetic estrogen called ethinyl estradiol.
Researchers had been looking for natural estrogen to use in combined hormonal contraceptive pills since its inception 60 years ago, but these had not been potent enough for those pills to be an effective form of hormonal contraceptive. This changed in 2011 when Zoely was introduced to the market.
Abigail Hegwood, MS, who carried out the study, told Medical News Today she wanted to investigate the new, natural estrogen on the market as she had become aware there was little epidemiological data on the side effects of specific progestins and estrogens. “I wanted to know [whether there is] a difference between these two estrogens. They just released this natural estrogen on the market. Does this possibly give us an opportunity to find a difference between formulations in terms of behavioral side effects?”
— Abigail Hegwood, MS, study author Effects of synthetic estrogen on behavior Three groups of 12 female rats […]
Synthetic estrogens used in birth control pills linked to anxiety in rats
