Starting in 2025, China is gradually increasing the statutory retirement age for male and female employees. However, little is known about how parental retirement delay affects the fertility intentions of adult children. This study investigates this issue using a 2 × 4 factorial survey experimental design (N = 773) and a difference-in-differences method to identify causal relationships. It further examines the mediating roles of grandparental economic support and childcare. The results show that the Delayed Retirement Policy significantly reduces both grandparental childcare and the fertility intentions of their adult children. The mediating pathway through reduced grandparental care is supported, whereas grandparental economic support plays no significant role. The magnitude of these effects varies by the duration of parental retirement delay, the gender of the parent affected, and whether both parents are impacted. Policy recommendations include promoting flexible retirement age options, expanding parental leave, and increasing the provision of childcare services to supplement intergenerational support.
