The Wisconsin Maternity Leave and Health (WMLH) Project is a large-scale, longitudinal study of women and their families from pregnancy through one year postpartum (Hyde, Klein, Essex, &. Clark, 1995). The focus of the WMLH Project is on women, work, maternity leave, and health (defined to include physical health, mental health, and the health of social relationships with husband or partner and child). The focus here is on data from a brief sex questionnaire that was administered during the interviews.

The data reported here have a number of substantial advantages over previous studies: (a) the respondents were not recruited for sex research, but rather for a study on a far less sensitive topic: maternity leave, work, and families; (b) the data include questions on behaviors other than in­tercourse (e. g., masturbation); (c) the data are longitudinal, following the same persons from pregnancy through 12 months postpartum; and (d) the data set includes reports from both mothers and fathers.