Although research in the STEM field has extensively examined its gendered characteristics, the vast majority of the literature has concentrated on educational transitions and young adults. More limited attention has been devoted to the longer-term work-family trajectories of STEM majors, and how these are linked to gender earnings gaps. In response, we exploit Finnish register data to identify the most common work-family trajectories followed by college educated men and women with STEM majors in ages 30–40 (N=150,796). Given marked differences in gender proportions across STEM fields, we distinguish computer science and engineering majors from natural science majors. In a second step, we assess gender differences in the returns to distinct work-family trajectories and within-gender differences. We report three main findings. First, women are able to combine a career in computer science and engineering and having children. Second, across occupations, mothers earn considerably less than fathers. This suggests that even though women can combine work and family, they do not benefit in terms of earnings. Third, beyond uncovering gender gaps, we show that a major mechanism underlying parental gender gaps is that men receive notable fatherhood premiums across work trajectories. For women, findings reveal more heterogeneous patterns. Among computer science and engineering majors, women have similar earnings across trajectories. Conversely, women with natural science majors gain from working in computer science and engineering.