To the Editor We thank Skovlund et al1 for their study investigating the association between hormonal contraception and depression. The authors reported a positive association between the 2 variables following a nationwide prospective cohort analysis of Danish women.
However, we feel that the lack of adjustment for onset of menarche could be a potential confounder as previous work has showed that early menarche is associated with higher levels of estrogen and is a strong independent risk factor for depression and other psychiatric disorders.2 Previous work hypothesized that the onset of menarche marks a transition point in the adolescent female, and this associated with an increased risk for depression.3 Given that early menarche and the associated higher estrogen levels are associated with depression, it is unclear whether data collected in the study would have been affected by the inclusion of former contraceptive users, as these users will have been exposed to elevated levels of sex steroids, which may influence any conclusions drawn from the results.
Karina IM, Sivakumaran P. Hormonal Contraception and Its Association With Depression. JAMA Psychiatry. 2017;74(3):301. doi:10.1001/jamapsychiatry.2016.3350