Urinary steroids in the periparturient and postpartum periods through early pregnancy in llamas.

Urinary steroids were determined daily in the periparturient and postpartum periods, including early pregnancy, in the female llama. Estrone sulfate (E(1)S) and pregnanediol glucuronide (PdG) concentrations were determined by enzyme immunoassay with values corrected for variations in urine concentration by creatinine. Estrone sulfate concentrations, elevated during the last 20 days of gestation through 12 hours before parturition, were declining at the time of delivery. Pregnanediol glucuronide concentrations followed a pattern similar to that of estrone sulfate except that values began to decrease 5 days before parturition. Values for both E(1)S and PdG were basal by 24 hours after delivery. The first significant elevation of estrone sulfate, indicative of initial follicle development, was observed 5 days after parturition. Pregnanediol glucuronide concentrations were low during the postpartum period until 4 to 5 days after breeding. The PdG values rose steadily following copulatory-induced ovulation, which was initiated at about 2 weeks postpartum; values continued to increase through the first 15 days of pregnancy.