During the last three decades, the "working mother" has become the norm rather than a rarity. In 1960, fewer than one in five mothers with children under age six (18.6 percent) were in the labor force. By 1987, this percentage had tripled, reaching 57 percent (U.S. Bureau of the Census, 1987, Table 624). Current participation levels for mothers of younger children are even more striking. Fifty-three percent of married mothers with children 1 year old or under are in the labor force (U. S. Bureau of the Census, 1987).
Previous research has consistently found that women with young children are less likely to participate in the labor force than those with only older children (Mincer, 1962; Gronau, 1973; Heckman, 1974). Today labor force activity reaches high levels soon after the birth of a child, and many women interrupt work for only short periods of time. Although half the new mothers have returned to work within a year after giving birth, the factors that affect the timing within that year are not well understood. Similarly, the factors that influence how long women work during their pregnancies have not been fully explored.
The analysis of women's increased work effort during pregnancy and rapid return to work after childbirth call for a research strategy using data that can distinguish among work patterns by month of return to work rather than by year. This paper uses panel data from the National Longitudinal Surveys of Youth (NLS-Y) to examine whether perinatal labor supply is positively related to women's real wages. We also expect to find a negative relation between mothers' work efforts and other household income.
This paper is organized into five sections: The first section reviews the previous work on this problem. The second section outlines a conceptual model of employment choice, and the third section describes the data and the empirical methods used. The fourth section presents results. Our conclusions are summarized in the final section.