Data on maternity leave arrangements and employment of American mothers around the time of their first birth are collected periodically in the Survey of Income and Program Participation (SIPP). Fertility statistics from the SIPP are also presented in a series of reports on program participation by mothers in the childbearing ages. The unique contribution of the SIPP data is that it is very detailed. SIPP data on Fertility are available from 1993 to present.
You can access the SIPP User Guide [PDF - 4.4M]