Objective: The association between a first, second, and third childbirth and in-work poverty in the short-and medium-term were assessed across age groups in the US and Germany. Background: Previous research on in-work poverty has concentrated on structural and ascriptive characteristics, while family processes-especially childbirths-received less attention. This gap was filled by adopting a processual life course approach. Method: Longitudinal data from the US and Germany were applied to between-within random effects models to estimate within-individual change in the probability of in-work poverty up to six years following a first, second, and third childbirth across age groups. Results: First, second, and third birth were associated with an immediate increase in the probability of inwork poverty (up to 10 and 5 percentage points in the US and in Germany, respectively). Among US adults aged 30 and younger probabilities increased in the medium term (from 9 to 15 percentage points for a first, 6 to 15 for a second, and 9 to 18 for a third birth), but remained unchanged for older adults in the US and all adults in Germany. Conclusion: There was no recovery in risk of in-work poverty in the medium-term following childbirth in the US and Germany. Increasing the labor market participation of adult household members via more and lowcost childcare options remains crucial. However, higher levels of income support and child benefits may be needed to avoid poverty.