Over the course of the 20^th century, many industrialized societies experienced increases in life expectancy and in the mean age at first birth (MAFB). These trends had an impact on the time that parents share with their children, i.e., the parental lifespan. While increasing life expectancy contributed positively, increasing MAFB led to a reduction in time spent as a parent. Using harmonized fertility and mortality data for 37 countries, we provide estimates of parental lifespan under a period perspective. Parental lifespan varies between 50-58 years for women and tends to be 10 years shorter for men. However, trends over time are country-specific and depend on the onset of fertility postponement relative to gains in life expectancy. By means of decomposition, we study the extent to which each of its two components where responsible for the observed changes in parental lifespan over time.