The Association Between Same-Sex Marriage Legalization and Youth Deaths by Suicide: A Multimethod Counterfactual Analysis

Purpose: To estimate the association between same-sex marriage legalization and deaths by suicide among youth.

Methods: The study used country-level suicide data sourced from the Global Burden of Disease Study for all 36 Organisation for Economic Co-operation and Development countries for the period 1991-2017. We analyzed the suicide rates of all youth, male youth, and female youth aged 10-24 years using multiple policy-evaluation methods-difference-in-differences, matrix completion, and generalized synthetic control via expectation-maximization-to estimate the impact of same-sex marriage legalization at the country level. Secondary analysis considered several covariate specifications, evaluated the immediacy and persistence of the estimated associations, and assessed whether any observed association was limited to early adopters of same-sex marriage.

Results: The state-of-the-art matrix completion analysis indicated that same-sex marriage legalization was associated with a decline in the youth suicide rate of 1.191 deaths per 100,000 individuals (95% CI = -1.66, -.64; p < .001), corresponding to a reduction of 17.90% compared to the youth suicide rate at the time of legalization. This decline was most pronounced in males for whom the suicide rate fell by 1.993 (CI = -2.76, -1.12; p < .001) compared to a decrease of .348 for female youth (CI = -.60, -.06; p = .02), corresponding to decreases of 19.98% and 10.90%, respectively. These associations persisted after legalization, but to differing degrees depending on model specification.

Conclusions: Developed countries that are yet to legalize same-sex marriage have an opportunity to put downward pressure on youth suicide.