The protective effect of pregnancy on risk for suicide attempt in a Swedish national cohort.

We used national Swedish registry data to investigate the nature of the association between pregnancy and decreased risk for suicide attempt (SA). Analyses included pregnant individuals aged 18-35, biological fathers, and matched controls born 1975-1995. Data were available for between 366,125 and 2,129,244 females (depending on the model) and 359,622 males. We evaluated risk for SA as a function of pregnancy status using three methods designed to strengthen causal inference: a matched cohort design, co-relative analyses, and within-individual analyses. In within-individual analyses, we also examined potential moderators of the pregnancy-SA association, and we conducted separate analyses in the unborn children's biological fathers. Across all analyses, pregnancy was associated with a lower risk of SA (ORs = 0.15-0.30). Moderation analyses indicated that the potentially protective effect of pregnancy was stronger in unmarried individuals, those with prior registration for externalizing or internalizing disorders, and younger individuals. Decreased SA risk was also observed during the postpartum period (ORs = 0.16-0.31) and in biological fathers (ORs = 0.67-0.82). These findings suggest that risk for non-fatal SA is substantially lower during pregnancy in expectant mothers and fathers, and the association between pregnancy and reduced SA risk may be causal.