Patterns of oestrogen and testosterone excretion during pregnancy in a gorilla (Gorilla gorilla).

Oestrogen and testosterone concentrations in the urine were determined by radioimmunoassay. Total oestrogen concentrations rose from 25 ng/mg creatinine in the non-pregnant animal to a mean of about 2 microgram/mg creatinine in the 50 days before term. There was a significant (P less than 0.001) correlation between oestrogen and testosterone concentrations until 11 days before parturition.