Many side effects of birth control pills are well known -- nausea, headaches, mood changes and weight gain -- but new research shows oral contraceptives actually change women's brains.
More than 150 million women worldwide use oral contraceptives, the most common of which are made of synthetic hormones. Considering their widespread use, the researchers set out to better understand the current and long-term effects of birth control pills on brain anatomy and emotional regulation.
The findings, published in the journal Frontiers in Endocrinology, indicate that the synthetic hormones in contraceptive pills might impair fear-regulating regions in women's brains.
"In our study, we show that healthy women currently using [oral contraceptives] had a thinner ventromedial prefrontal cortex than men," lead author Alexandra Brouillard said in a statement. "This part of the prefrontal cortex is thought to sustain emotion regulation, such as decreasing fear signals in the context of a safe situation."
The study recruited women who were currently using the pills, women who used them previously but not at the time of the study, women who never used any form of hormonal contraception, and men. Researchers utilized MRI scans to analyze participants' brains and found that only women who were currently on the pill had thinning in part of the brain that's responsible for processing risk and fear, and controlling emotions.
"Our result suggests that [oral contraceptives] may confer a risk factor for emotion regulation deficits during their current use," Brouillard said.
Researchers said the findings are significant given that many teenage girls start using oral contraceptives during adolescence, a sensitive period in brain development.
The study noted that impacts to the brain from use of the pills may be reversible once intake is discontinued, and that there appears to be no lasting effects.
"The objective of our work is not to counter the use of [oral contraceptives], but it is important to be aware that the pill can have an effect on the brain," Brouillard said. "Our aim is to increase scientific interest in women's health and raise awareness about early prescription of [oral contraceptives] and brain development, a highly unknown topic."