Objective To finely depict the longitudinal associations between sex‐specific reproductive factors and dementia or cognitive decline.

Background Sex difference exists in the prevalence of dementia and cognitive decline. The impacts of sex‐specific reproductive risk factors across the lifespan on the risk of dementia or cognitive decline are still unclear. 

Methods PubMed, EMBASE, and Cochrane Library were searched up to January 2023. Studies focused on the associ‐ ations of female‐ and male‐specific reproductive factors with dementia or cognitive decline were included. Multivaria‐ ble‐adjusted effects were pooled via the random effect models. Evidence credibility was scored by the GRADE system. The study protocol was pre‐registered in PROSPERO and the registration number is CRD42021278732. 

Results A total of 94 studies were identified for evidence synthesis, comprising 9,839,964 females and 3,436,520 males. Among the identified studies, 63 of them were included in the meta‐analysis. According to the results, seven female‐specific reproductive factors including late menarche (risk increase by 15%), nulliparous (11%), grand parity (32%), bilateral oophorectomy (8%), short reproductive period (14%), early menopause (22%), increased estradiol level (46%), and two male‐specific reproductive factors, androgen deprivation therapy (18%), and serum sex hormone– binding globulin (22%) were associated with an elevated risk of dementia or cognitive decline. 

Conclusions These findings potentially reflect sex hormone‐driven discrepancy in the occurrence of dementia and could help build sex‐based precise strategies for preventing dementia.