Based on the conservation of resources model we examined the trajectories of work–home conflict (WHC) for women and their partners in the context of the major life event of having a(nother) child and mothers’ subsequent return to work.We further examined how these trajectories relate to both parents’ mental health. In the context of a cohort study (the “DResdner Studie zu Elternschaft,Arbeit undMentaler Gesundheit”–Dresden Study on Parenting, Work, and Mental Health), we examined 347 women and 223 men at three measurement points: during pregnancy (Time 1), 14 months after birth (Time 2), and 2 years after birth (Time 3; when all women had returned to work). We found three WHC profiles for women: (a) a low-WHC profile, (b) an average-WHC profile, and (c) a high-and-increasing-WHC profile. All profiles differed in their starting levels. Overall, women with a low-WHC profile reported the best mental health, while the other profiles showed poorer mental health. Partners of women with these latter profiles (b and c) reported comparable mental health, but partners of women with low-WHC profile reported partly poorermental health. Similar patterns were found for subsamples of coupleswhere the women had returned to work prior to Time 2 and a subsample of first-time parents. We conclude that high and average initial levels of WHC are required for the birth of a child to trigger a resource loss which manifests in worse mental health among women. We integrate the findings with respect to conservation of resources model theory and identify the advantages and limitations of the resource perspective in interpreting WHC trajectory outcomes.