Researchers have found that women taking oral contraceptives, commonly known as birth control pills, had significantly smaller hypothalamus volume, compared to women not taking the pill. Located at the base of the brain above the pituitary gland, the hypothalamus produces hormones and helps regulate essential bodily functions including body temperature, mood, appetite, sex drive, sleep cycles, and heart rate.

Structural effects of sex hormones, including oral contraceptive pills, on the human hypothalamus, have never been reported, according to the researchers. This may be in part because validated methods to quantitatively analyse MRI exams of the hypothalamus have not been available.