A connection between oral contraceptives and depression has been established in a study which examined a vast number of subjects - 250,000 women were tracked from birth until menopause - performed by Uppsala University in Sweden.
Those who start birth control pills in their teens were found to have a nearly 130 percent higher rate of depressive symptoms. A similar pattern has emerged among adult birth control pill users with a solid rate of 92 percent.
Seen for all women in the study, the risk of receiving a regular depression diagnosis increased by 73 percent during the first two years of contraceptive pill use.
The particularly strong impact of birth control pills on teenagers can be attributed to the hormonal changes caused by puberty, according to the study's author, Therese Johansson, a PhD student of Uppsala University's Department of Immunology, Genetics and Pathology, Genomics and Neurobiology. Because women in that age group have already undergone significant hormonal change, they are more susceptible not only to hormonal changes but also to other life experiences.
Teenage pill users were found to have an increased rate of depression even after they stopped using the pill. A similar effect was not observed in adult users.
"Although contraceptives have many benefits for women, both medical professionals and patients should be informed of the side effects identified in both this and previous research," Johansson said in a statement, admitting that because the study is observational, there are limits to what may be concluded regarding causation.
How the Research Was Carried Out
The study focused on the use of so-called combined oral contraceptives (in everyday life often referred to as "The Pill") launched in the Sixties and commonly regarded as one of the driving forces of the sexual revolution. The contraceptives contain progestin, a compound that mimics the hormone progesterone, and estrogen. Progestin prevents ovulation and thickens cervical mucus to prevent sperm from passing into the uterus. Estrogen, in turn, thins the lining of the uterus to make implantation of a fertilized egg more difficult.
In the study, medical information from UK Biobank was used. The bank harbors extensive data from questionnaires, interviews, physical health measures, biological samples, and imaging, as well as participants' health records, including hospital inpatient data, primary care data, cancer, and death registry data.
The researchers focused on collecting data on the women's use of contraceptives when they were first diagnosed with depression, and when they first experienced depressive symptoms without necessarily receiving a diagnosis.
Though internationally, many women are known to stop using birth control pills because of perceived mood effects, scientific research has so far not provided a clear picture of why birth control pills cause poor mental health and depression and further studies are needed.
So far, educating users of oral contraceptives, screening for depression and informing primary healthcare practitioners of related depression is also necessary, the study concluded.