The proportion of life spent caring for dependent children is a defining feature of life courses. This study uses Swedish register data to analyze the period of life spent as parents to children no older than 18 as a salient difference between singleand multiple-partner fertility trajectories. Individuals who have children with more than one partner spend a much longer time as parents to dependent children than those who have children with one partner, on average 8.2 more years among men and 6.2 more years among women. Cross-partner birth spacing is a more powerful proximate cause of this gap than completed fertility. We argue that an extended time parenthood is part and parcel to multi-partner fertility and discuss implications of this.