Pre- and postpartum sex steroids in female marmosets (Callithrix kuhlii): Is there a link with infant survivorship and maternal behavior?

Recent studies in primates have suggested that pre- and peripartum sex ster oid hormones may be important determinants of maternal behavior and motivat ion, since higher levels of prepartum estrogen are associated with maternal competency and infant survivorship. To test the cross-species generality o f this finding, we monitored excreted profiles of estradiol (E-2), progeste rone metabolites (pregnanediol glucuronide; PdG), and E-2: PdG ratios throu ghout pregnancy in black tufted-ear marmosets (Callithrix kuhlii). Addition ally, we wanted to determine the extent to which variability in maternal ca rrying effort was related to hormonal factors and relative levels of matern al experience. For six females, hormonal profiles were determined by enzyme immunoassay for two pregnancies, one in which infants survived at least 2 weeks postpartum and one in which infants did not survive. Our within-subje cts analyses revealed significant differences in mean prepartum E-2 levels for females in the different infant survival conditions. In contrast to pre vious findings, however, females exhibited significantly higher prepartum E -2 levels when their infants did not survive a minimum of 2 weeks postpartu m, relative to when their infants did survive. Maternal carrying effort was also negatively and significantly correlated with prepartum E-2 levels. Un like previous reports in callitrichid primates, then, our data suggest that high concentrations of prepartum E-2 in callitrichid primates are not nece ssarily associated with competent maternal behavior and may instead be asso ciated with poor infant survivorship and inadequate maternal care. Further, our results appear to be convergent with research focusing on human mother s and may represent a common underlying mechanism linking prepartum estroge n and postpartum affect and behavior in some primates. (C) 2000 Academic Pr ess.