Peripartum sex steroid profiles and endocrine correlates of postpartum maternal behavior in captive gorillas (Gorilla gorilla gorilla)

An association between pregnancy levels of estrogen and progesterone and ma ternal behavior has been demonstrated in several taxonomic orders of nonpri mate and primate mammals, but has not so far been investigated in the goril la. In this study we investigated whether prepartum titers of urinary estro ne conjugates (E1C) or pregnanediol-3 alpha -glucuronide (PdG) were related to postpartum maternal behavior in eight multiparous Western lowland goril la females (Gorilla gorilla gorilla) housed in four zoological gardens. Uri ne samples were collected from each study animal for 14 days prepartum and 14 days postpartum, and measures of maternal responsiveness were scored dur ing the first 15 days postpartum. Urine samples were assayed with radioimmu noassay for E1C and PdG. Results for the peripartum profiles of urinary E1C , as well as postpartum profiles of PdG, agree with previous findings for t he gorilla, while results for late-pregnancy profiles of urinary PdG were i nconclusive in confirming a prepartum increase or decrease. Neither prepart um levels of E1C or PdG, nor the E1C/PdG ratio were found to be related to measures of postpartum maternal behavior. This lack of association between late-pregnancy E1C titers per se and postpartum maternal behavior is contra ry to findings in nonprimate and other primate species. (C) 2001 Elsevier S cience.