Using Spanish Social Security records, we document the channels through which mothers fall onto a lower earnings track, such as shifting into part- time work, accumulating lower experience, or transitioning to lower-paying jobs, and are able to explain 71 percent of the unconditional individual fixed- effects motherhood wage gap. The earnings trajectories' analysis reveals that "mothers to be" experience important relative earnings increases several years before giving birth but this earnings' advantage falls right after birth, taking in average nine years to recover. Heterogeneity matters as most of the motherhood dip is driven by workers with permanent contracts. (Contains 4 tables, 2 figures, and 21 footnotes.)