A total of 570 pregnant women and 550 of their husbands or partners (all partners were men) were recruited for participation in the WMLH Project (for a more detailed description of recruiting procedures and char­acteristics of the sample, see Hyde et al., 1995). Attempts were made to recruit as diverse a sample as possible. Approximately 78% of the sample resided in the Milwaukee area, and 22% in the Madison, Wisconsin, area. To be included in the sample, female participants had to be over the age of 18, and married to or living with the baby’s father at the time of entry into the study. The latter criterion was instituted because we did not want to make maternity leave just a women’s issue, but wanted to include men fully in the study.

The average age of the mothers at the beginning of the study was 29 years, ranging between 20 and 43 years; 95% of the mothers were married to the father. Ninety-three percent of the mothers were White (not of Hispanic origin); 2.6% were Black (not of Hispanic origin); 1.8% were Hispanic; 1.9% were Native American; and 0.7% were Asian Amer­ican. In regard to education, 1.8% had less than a high school education; 15.4% graduated from high school or had a GED; 9.6% received some technical training beyond high school; 19.8% had some college; 34.9% had earned a college degree; 7.5% received some education beyond the college degree; and 10.9% had completed a masters, doctoral, or profes­sional degree.

At the time of the first interview, 81.5% of the women were em­ployed. For 38% of the women this was their first child, and for the re­maining 62% it was a second or later child.

Mothers were interviewed in their homes by a female interviewer on each of four occasions: (a) during the fifth month of pregnancy (Time 1); (b) 1 month after the birth (Time 2); (c) 4 months after the birth (Time 3); and (d) 12 months after the birth (Time 4). In addition, mothers com­pleted mail-out questionnaires on their own in advance of the interview and returned them to the interviewer. Fathers were interviewed by tele­phone and completed a mail-out questionnaire on each of the same four occasions.[12]

One page of questions about sexual behavior was part of the mothers’ home interview. About halfway through the interview, the page was handed to the woman, who filled it out in privacy, placed it in a sealed envelope, and returned it to the interviewer.[13] For fathers, the page of questions about sexual behavior was included in the mail-out question­naire.