Urinary estrogen excretion during pregnancy in the gorilla (Gorilla gorilla), orangutan (Pongo pygmaeus) and the human (Homo sapiens).

Urinary estrogen components were separated, identified and quantified throughout the pregnancy of the gorilla (Gorilla gorilla) and orangutan (Pongo pygmaeus) and compared to estrogen levels in normal human pregnancies. Fetal and neonatal adrenals from each species were also compared in terms of weight and relative amounts of fetal zone. The results demonstrate that gorillas and chimpanzees excrete 4- to 5-fold less estrogen during pregnancy than the human and orangutan which are similar to each other. The lower estrogen excretion appears to be related to a smaller fetal adrenal in both the gorilla and chimpanzee which reveal both a reduced adrenal weight and increased definitive to fetal zone ratio when compared to either the human or orangutan.