Two studies were undertaken (1) to determine whether human mothers undergo a change in maternal responsiveness during pregnancy before the birth of the baby, as shown for other mammalian species, and (2) to establish whether a relation exists between changes in maternal feelings and attitudes and changes in hormones. In both studies prospective first-time mothers completed an extensive set of questionnaires, covering a broad range of issues, including a set of 76- to 100-item likert scales concerning attitudes toward infants, childbirth, pregnancy, caretaking, and other interpersonal relationships. In the first cross-sectional study, mothers completed the questionnaires at one of seven time points, ranging from prior to pregnancy to 3 months postpartum. In the longitudinal study, questionnaires were completed repeatedly throughout this same time period. In addition, blood was taken at these same time points and assayed by RIA for plasma concentrations of the steroids, estradiol, progesterone, testosterone, and cortisol. The primary findings are (1) feelings of nurturance grow during pregnancy and from pregnancy to postpartum; in the cross-sectional study, for most of the factors relating to infants or mothering, pregnancy and postpartum responses were more positive than prepregnancy responses; in the longitudinal study, many of these factors also showed elevations across pregnancy itself, as well as further elevations with the birth of the infant. (2) Pregnancy hormones were not related to the growth of attachment to the infant across pregnancy. (3) However, the pattern of change in the ratio of estradiol to progesterone from early to late pregnancy was related to postpartum attachment feelings. (4) Finally, hormonal correlates of attachment feelings may reflect effects both on feelings of nurturance directly and, indirectly, on mothers' feelings of well-being.