Birth Control Pills May Disrupt a Woman's Response to Stress

Scientists found that women taking oral contraceptives may respond to stress differently than those not on the pill, which could impact their risk for inflammation-related health conditions.

Hormonal contraceptives like the birth control pill can alleviate the stress and worry about unintended pregnancy. However, a new study suggests that the pill may also change a woman's biological response to stressors, and this disruption could lead to chronic inflammation.

The study, published in the January 2024 issue of Brain, Behavior, and Immunity, examined the stress responses of women taking birth control pills versus those who did not take the pill.

To conduct the research, scientists from the UCLA Department of Psychiatry and Biobehavioral Sciences' Laboratory for Stress Assessment and Research recruited 127 American women ages 18 to 37 from a private university between 2021 and 2022. Sixty participants reported currently using first, second, or third generation combined oral contraceptives, and 67 said they did not take the pill.

The scientists collected the participants' saliva samples before they took a social stress test, which included giving a 5-minute speech about why they deserve their dream job in front of a researcher who offered no positive encouragement and displayed no reactions to the speaker.

Then, the women took a timed mental math test, which required them to count backward from 1,022 by intervals of 13.

After the stress tests, the researchers collected another saliva sample and asked the participants to rate their stress levels and mood.

The researchers analyzed the saliva samples and found that cortisol levels — a hormone released during stress — increased in both groups. However, women taking birth control pills had a stress response that differed from those not taking the pill.

Specifically, before and after the stress test, oral contraceptive users showed increased levels of TNF-α — an inflammatory cytokine that accompanies cortisol release. In contrast, those who did not take the pill showed increases in interleukin-6 (IL-6) —another proinflammatory cytokine.

In addition to these molecular differences, the participants who used the pill also reported feeling more stressed out and experienced a more negative mood than those not taking oral contraceptives, which may indicate a less adaptive stress response.

The researchers say that TNF-α may be associated with a male-like response to stress, while IL-6 may accompany a more female-typical stress response. Moreover, they suggest that hormones in the birth control pill may bind to testosterone receptors, which could explain the differences in inflammatory stress responses found in the study.

These differences could also impact health, as a 2021 study found that higher TNF-α levels may play a critical role in the development of certain autoimmune disorders.

Though the study suggests some birth control pill users may have potentially harmful responses to stress, researchers will need to investigate their findings further in order to better understand how this impacts the health of millions of women.