Birth control pills may alter how women perceive fear. Here’s how

Birth control pills may affect the brain's fear-regulating regions in women, potentially increasing the risk of anxiety and stress-related disorders, according to a study.

Birth control pills may adversely affect the brain’s fear-regulating regions in women, potentially increasing the risk of anxiety and stress-related disorders, according to a recent Canadian study.

The peer-reviewed study out of Quebec and published in Frontiers in Endocrinology on Tuesday found that the ventromedial prefrontal cortex, a brain region critical for regulating fear and emotions, was thinner for women currently taking oral contraceptives versus for men and women who never used the pill.

“This part of the prefrontal cortex is thought to sustain emotion regulation, such as decreasing fear signals in the context of a safe situation. Our result may represent a mechanism by which oral contraceptives could impair emotion regulation in women,” Alexandra Brouillard, a researcher at Université du Québec à Montréal and first author of the study, said in a Tuesday media release.

More than 150 million women worldwide use oral contraceptives, according to 2019 United Nations data. In Canada, 2015 data showed that nearly three-quarters of Canadian women use oral contraceptives at some point during their reproductive lives. Data from the Society of Obstetricians and Gynaecologists of Canada shows that oral contraceptive pill use declined among those aged 15 to 19 from 69 per cent in 2006 to 32 per cent in 2016.

Combination birth control pills are the most common type of oral contraceptive, and they contain forms of the hormones estrogen and progestin. These hormones are known to modulate the brain network involved in fear processes, the authors of the study state.

In order to find the long-lasting effects oral birth control may have on the fear-related brain region, researchers recruited women ages 23 to 35 who were currently using oral birth control, women who used to be on it, women who never used any form of hormonal contraception, and men.

They found that women who were currently using oral birth control had a thinner ventromedial prefrontal cortex.

The researchers also pointed out another finding: the potential reversibility of the impacts of birth control pill use once a person stops taking them. This is because the effect on the ventromedial prefrontal cortex was seen exclusively in current users and not in past users, the study stated.