Several studies have demonstrated that stepfamily couples have a higher risk of childbearing than couples in a stable union with the same total number of children. Analysing retrospective data from a nationally representative sample of Swedish adults, we find that the risk of a second or third birth is higher when it is the first or second child in a new union. We also find a faster pace of childbearing after stepfamily formation than after a shared birth. The risk of a second birth (in total) is only a little higher in the first two years after stepfamily formation than in the first two years after a shared birth, and thereafter the risk is lower for stepfamilies. The risk of a third birth (in total) is particularly high early in the stepfamily union and remains higher than that of couples with two shared children for at least five years. The stepfamily difference was lower after than before 1980, when the Swedish government introduced parental leave incentives for short birth intervals.