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 single- and 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.