Background: Marriage is consistently identified as a protective factor for suicidality, but it remains unclear whether this relationship varies by time elapsed since the transition to marriage.

Methods: Participants were 15,870 individuals (52 % female, mean age = 44.63 years, age range = 18-99 years) from the Collaborative Psychiatric Epidemiology Surveys. Cox proportional hazards models were used to test the relationship between marriage, as well as time elapsed since the transition to marriage (0-5 years, 6-10 years, or 11+ years), and suicidal ideation. Years of education and race and ethnicity were included as covariates, and analyses were stratified by sex. Separate hazard ratios were estimated for individuals aged <30 years and 30+ years to address violations of the proportionality assumption.

Results: Being married was associated with lower risk for suicidal ideation across age and sex. Among individuals aged <30 years, marriage was reliably associated with lower risk for suicidal ideation, regardless of the time elapsed since marriage. For individuals aged 30+ years, being married for 0-5 years or 6-10 years was associated with increased risk for suicidal ideation, particularly in females. Being married for 11+ years was associated with decreased risk across sex.

Limitations: Analyses focused on participants' first marriage and did not examine mediators of the association between marriage and suicidal ideation.

Conclusions: Overall, being married protects against suicidal ideation. However, among individuals aged 30 years or older, the first 10 years of marriage are associated with elevated risk for suicidal thoughts, and clinical outreach may be warranted.