There is lots of ongoing debate about the breast cancer-depression link. For example, one study published in Cancer Research found a higher risk for breast cancer among women taking high-dose estrogen birth control pills. A review of 54 studies in 1996 found that women have a slightly higher risk of breast cancer while they’re taking birth control pills that contain both estrogen and progestin and during the 10 years after they stop taking the pills. And results from the 2010 Nurses’ Health Study found that use slightly increased risk, especially among women taking triphasic pills, which alter doses of hormones over three stages of the monthly cycle.
Hormonal contraceptives (the pill, the patch, and the vaginal ring) all contain a small amount of man-made estrogen and progestin hormones. These hormones work to inhibit the body's natural cyclical hormones to prevent pregnancy. Pregnancy is prevented by a combination of factors. The hormonal contraceptive usually stops the body from ovulating . Hormonal contraceptives also change the cervical mucus to make it difficult for the sperm to go through the cervix and find an egg. Hormonal contraceptives can also prevent pregnancy by changing the lining of the womb so it's unlikely the fertilized egg will be implanted.