Purpose This paper investigates the effects of childbirth on female employment in Vietnam from 1989 to 2019. Design/methodology/approach Using Vietnam census data from 1989 to 2019, this study constructs a pseudo-event panel by matching parents at different stages of the parenting lifecycle with demographically similar counterparts without children. Findings The results show a sharp and persistent decline in female employment following childbirth, with no comparable effect on men. This paper further documents significant variations in the magnitude of the child penalty across regions and over time and finds that women who are married, live in urban areas, belong to the ethnic majority, are more educated or have migrated face a significantly greater child penalty. In contrast, women who co-reside with their child's grandparents or work in agriculture or the public sector appear to have a lower child penalty. Originality/value This study is among the few to measure and analyze the child penalty in a developing country. In particular, it provides the first systematic province-level analysis of the child penalty in Vietnam. Moreover, this study has policy implications for a developing country during a period of economic transformation amid rising gender inequality.