Validated protocols for evaluating maternally mediated mechanisms of early pregnancy failure in rodents are needed for use in the risk assessment process. To supplement previous efforts in the validation of a panel of protocols assembled for the purpose, bromoergocryptine (BEC) was used as a model compound because it is known to inhibit pituitary prolactin secretion. BEC was tested using the early pregnancy protocol (EPP), the decidual cell response technique (DCR), the pre- vs postimplantation protocol (PPP), and embryo transport rate analysis (ETRA). These protocols evaluate the effects of chemicals on multiple endpoints following exposure during (1) the first 8 days of pregnancy, (2) early pseudopregnancy accompanied by decidual induction, (3) the pre- and postimplantation intervals of early pregnancy, or (4) the period of embryo transport. In the EPP, dosing with BEC during Days 1-8 of pregnancy reduced the number of implantation sites found on Day 9 as well as serum progesterone. The DCR technique revealed a dose-dependent inhibition of decidual growth concomitant with decreased serum progesterone as a result of BEC treatment. A modified DCR technique using hormone-supplemented ovariectomized rats demonstrated that BEC did not impair decidual growth in the presence of adequate progestogenic support. (Copyright (c) 1991 by the Society of Toxicology.)