The finding: This Danish prospective cohort study from the University of Copenhagen combines data from two national registers and follows more than one million women and adolescents, aged 15 to 34 years, who did not have a prior depression diagnosis, did not redeem a prescription for antidepressants, did not have other major psychiatric diagnoses, cancer, venous thrombosis, or infertility treatment, from January 2000 to December 2013. Adjusted incidence rate ratios were calculated for first use of an antidepressant and first diagnosis of depression at a psychiatric hospital. After analysing the data, the researchers concluded that use of hormonal contraception, especially among adolescents, was associated with subsequent use of antidepressants and a first diagnosis of depression, suggesting depression as a potential adverse effect of hormonal contraceptive use.

Strength and weaknesses: The sheer number of women and adolescents followed is an obvious strength. Also, the study is clear that only an association exists between the use of hormonal contraception and depression, which is appropriate considering the study type is not able to prove cause and effect. Along these lines, the researchers believe further studies are warranted to examine depression as an adverse effect of hormonal contraceptive use. A weakness of the study is that not all patients prescribed antidepressants are depressed; antidepressants are commonly prescribed for anxiety disorders as well. Furthermore, only a very small percentage (2%) of the users of hormonal contraception were diagnosed with depression for the first time, suggesting that if the risk of depression exists with such use, it is still very low.

Relevance: This research is highly relevant to the field of Women’s Mental Health given the prevalence of hormonal contraceptive use. If we uncover a clear cause-effect relationship between depression and hormonal contraception, it could have quite an impact on the way we presently prescribe contraception.