Women have been using birth control pills since the 1960s, but researchers still don’t know everything about the body’s complex response to the hormone-laden little pill. A new study warns that birth control pills can affect the body’s ability to regulate stress.

Researchers from Aarhus University in Denmark and the United States studied the stress response of 131 young women when they took a blood sample. Some of the women were taking birth control pills, others were not, reports News.ro.

The researchers specifically measured the level of the stress hormone ACTH in the women’s blood.

A study found that 15 minutes of social activity after a blood draw reduced stress hormone levels in women not taking birth control pills.

In contrast, ACTH levels do not decrease in women taking birth control pills.

To avoid additional stress for the participants, a small intravenous catheter was inserted during the first blood sample collection. In this way, the researchers were able to collect blood after social activity without having to repeatedly prick the women with a needle.

The average age of the participants was 20.5 years. After the blood sample was taken, they could participate in one of six different group activities, such as playing board games, getting to know each other during a group activity, singing together, or participating in a religious service.

It has long been known that birth control pills affect a woman’s response to stress. However, looking at the stress hormone ACTH in relation to social activity is a new approach.

“Being with other people is one of the most effective ways to reduce stress. Our results are very important because they indicate that people who take birth control pills do not experience the same reduction in stress hormone levels in relation to social activity as people who do not use the treatment,” says Michael Winterdahl, visiting researcher in the department of neuropsychiatry. translator of the Department of Clinical Medicine and one of the authors of the study.

More guesswork

The recent study differs from previous ones, which focused mainly on cortisol, the stress hormone, under extreme circumstances.

In this study, the researchers measured the stress hormone ACTH, which changes much faster than cortisol, and allows for the observation and analysis of rapid changes in a person’s response to stress.

“By studying ACTH levels, we’re taking another step toward understanding how the brain regulates stress, because ACTH acts as a neurotransmitter from the brain to the adrenal cortex, which produces cortisol,” says Michael Winterdahl.

By studying the level of ACTH, the researchers gained insight into the rapid response mechanism that controls the body’s response to stress.

Birth control pills are known to affect the hypothalamic-pituitary-adrenal (HPA) system. As the name suggests, the stress signal travels from the hypothalamus in the brain through the pituitary gland, which secretes ACTH, to the adrenal glands, which secrete cortisol.

Researchers still need a final explanation for why birth control pill users don’t experience the same reduction in the stress hormone associated with social activities as people who don’t take the pill.

“There are several competing hypotheses that try to explain the lower cortisol levels in people taking birth control pills. Our research has pushed us closer to an explanation that focuses on the brain and ACTH dynamics. The biochemistry is complex, but we work from the hypothesis that birth control pills can suppress the body’s own production of progesterone,” says Michael Winterdahl.

Progesterone is cleaved into the hormone allopregnanolone (ALLO), which is involved in a wide range of sedative effects and can influence the stress response.

Different phases of the menstrual cycle

Women who used birth control pills and women who did not participate in the study. Women had different phases of the menstrual cycle.

The study found that the stress response of women who did not take birth control pills depended on their monthly menstrual cycle.

The group’s stress-reduction activities had no effect on ACTH levels in women who were in the proliferative phase of their cycle — right after menstruation ends and the body begins to produce hormones to trigger ovulation.

“Progesterone levels are very low during the proliferative phase of the natural cycle. This leads to minimal conversion of progesterone into the hormone allopregnanolone. Because allopregnanolone is important for activating receptors that regulate the stress response, we did not see a decrease in ACTH levels in naturally cycled women who had just menstruated,” explained Michael Winterdahl.

He notes that women are also typically more physically active during the proliferative phase, and this can be seen as an adaptation where stress responses and behavior change with the cycle.

Women who take birth control pills have a “disabled” stress response, meaning they cannot adapt to a certain situation.

Research still can’t explain exactly how it affects women. Therefore, further research is needed to elucidate the complex mechanisms involved in the correlation between hormone levels and stress response.

“It is also worth emphasizing that birth control pills are not just contraceptives. There are different generations of pills, each with its own chemical structure due to the hormones used, which means the pills have different side effect profiles. Therefore, it is very important that our experiments are repeated with a larger and more diverse group of subjects,” says Michael Winterdahl.