Serum oestradiol, progesterone, chorionic gonadotrophin and prolactin concentrations during pregnancy in the Bolivian squirrel monkey (Saimiri sciureus).

Concentrations of chorionic gonadotrophin gradually increased during early pregnancy, reached maximum values at mid-gestation, then declined to low levels. Oestradiol-17 beta concentrations were relatively low (300-600 pg/ml) during early pregnancy, increased thereafter to high levels (10-35 ng/ml), and then appeared to decline towards term. Concentrations of progesterone were constant (100-200 ng/ml) for the first 15 weeks of gestation, suggesting that sequential measurements of progesterone could be used to diagnose early pregnancy. Prolactin concentrations rose during pregnancy, reaching maximum values at term.