The birth control pill is the most commonly prescribed form of contraception in the US. Approximately 25% of women aged 15-44 who currently use contraception reported using the pill as their method of choice.(1)
The most common use for oral contraceptive pills is to prevent unwanted pregnancy however, “the pill” has also been used as a band aid solution for many hormonal associated issues such as painful menstruation (dysmenorrhea), polycystic ovary syndrome (PCOS), irregular menstruation, heavy periods (menorrhagia), premenstrual dysphoric disorder (PMDD), premenstrual syndrome (PMS) and acne.
Although it's often overlooked, it's common for women to be aware of the serious health risks associated with birth control such as blood clots, stroke, breast cancer, gallbladder disease and liver disease. But when it comes to the effects that Oral Contraceptives (OC) have on the brain, women have been left in the dark.
Despite the multitude of uses of birth control amongst millions of women, many are unaware of:
- The influence of OCs on the HPA Axis reactivity and mood regulation
- The the link between OCs and changes in brain structure and function
- OC potential impact on mate selection and successful reproduction
There is so much more to know about birth control and be cautious of, aside from the common known risk of blood clots.
Oral Contraceptives and their Influence on HPA-Axis Reactivity and Mood
Ever since the introduction to the first formulation of the pill in 1960 women have expressed the experience of mood related changes such as depression and anxiety.
Oral contraceptive pills are either combined OCs which include estrogen and progesterone (progestin) or progesterone (progestin)-only OCs.(1)
Progestin (the synthetic form of progesterone) is made by altering the molecular structure of testosterone and has the ability to potentially stimulate our testosterone receptors and cortisol receptors in the body.(2) Multiple studies evaluating the influence of OCs on the HPA-Axis have concluded OCs are associated with abnormal HPA Axis reactivity.(3) Not only does the HPA-Axis play a role in many physiological functions in the body but it is responsible for how we respond to stress. Researchers have revealed that women who take OCs have elevated levels of free circulating cortisol in the blood, similar to those with chronic stress.(3)
When you think about the women you know who are on birth control or have been on birth control in the past, you may recall how common it is to hear women express how they’ve experienced negative effects in their mood and mental wellbeing. This may be due to the fact that chronic stress subsequently resulting in dysregulation of HPA reactivity is associated with mood disorders such as anxiety, depression, mood swings and irritability.
The Effects of Oral Contraceptives on Brain Structure and Function
Another reason for mood disorders while taking birth control can be linked to alterations in the structure and function of the brain while on the pill. In a recent study evaluating the brain activity of women through the use of “emotional memory testing”, which involved recalling images that were either negative, positive or neutral, along with structural and functional MRI evaluations, there were differences in results between OC users and non OC users.
Results showed that women who were on birth control showed higher activity in the prefrontal cortex when looking at the negatively-charged pictures compared to the women who had never taken birth control.(4) This shows that their brains worked harder to remember the negative images, suggesting that women's brains on birth control are more sensitive to negatively charged information.(5) It was also evident that OC use is linked to structural changes in parts of the brain involved in memory and emotional processing.(4)
Are you really attracted to him or is it just the pill?
It almost seems crazy to think that a pill can cloud your judgment when it comes to knowing who you're attracted to, who you choose to date and who you choose to enter a relationship with. Surprisingly, many women have expressed feeling less attracted to their partner who they’ve met while on the pill, once they've decided to come off it.
When it comes to women and men's attraction to one another, there is a biological innate component that plays a role in physical attraction and choosing the right partner to have children with. Genetic quality is associated with offspring survival (immune strength) and reproductive success. Oder acts as a cue for mate suitability and an indicator of compatibility between potential mates’ immune systems.
When a woman goes through her natural menstrual cycle she is more attracted to the odour of men whose immune system is dissimilar to hers.(6) This dissimilarity is preferred because the larger the dissimilarity between immune systems the more enhanced the immune system of their future child will be.
The use of contraceptives deters women from their natural menstrual cycle by mimicking pregnancy subsequently interfering with this innate mate preference. It has been evident that women using birth control actually prefer the odour of partners with similar immune systems to theirs and find these men more physically attractive.(6)
This alteration in women's mate preference may adversely affect the adaptability of the immune system in children who are born to couples who met during contraceptive pill use. A study revealed that children born to mothers who were on the pill when they met their father were more prone to infections, required more medical care and suffered from a higher frequency of common sickness, compared to children whose parents met without the mother being on the pill.
Should women avoid using birth control and seek alternatives?
Ultimately it's a woman's individual choice on what she decides to do with her body. There is power in that choice when women are educated on how certain products and medications can affect their brain health, reproductive health, mental health and overall wellbeing.
With current and growing research on the impact of oral contraceptives in women's health, women should be encouraged to include mental health and brain health in discussions with their trusted health care practitioner about contraceptive drug use. Women should always be able to make properly informed decisions when it comes to their health.
Renee Campbell, Lifestyle + Wellness Content Creator
Cooper DB, Patel P, Mahdy H. Oral Contraceptive Pills. [Updated 2022 Sep 6]. https://www.ncbi.nlm.nih.gov/books/NBK430882/
Corbyn, Z. (2019). Dr Sarah E Hill: ‘We have a blind spot about how the pill influences women’s brains’. The Guardian. https://www.theguardian.com/society/2019/oct/19/dr-sarah-e-hill-how-pill-influences-womens-brains
Hertel J et al. Evidence for Stress-like Alterations in the HPA-Axis in Women Taking Oral Contraceptives. Sci Rep. 2017 Oct 26;7(1):14111. doi: 10.1038/s41598-017-13927-7.
R. Sharma et al. Use of the birth control pill affects stress reactivity and brain structure and function. Horm. Behav. (2020)
The Royal Mental Health - Care & Research (2020). New research reveals effects of oral contraceptives on brain development. The Guardian. https://www.theroyal.ca/news/new-research-reveals-effects-oral-contraceptives-brain-development
Birnbaum, G. E. (2017, May). Can contraceptives affect the health of future children? Psychology Today. Retrieved from https://www.psychologytoday.com/ca/blog/intimately-connected/201705/can-contraceptives-affect-the-health-future-children