Serum cystyl aminopeptidase activity in the 36th week of pregnancy.

Serum cystyl aminopeptidase (CAS) activity was estimated at 36 weeks' gestation in 209 normotensive pregnancies. The highest activity was found in 31 women who had spontaneous deliveries before 38 weeks' gestation and the lowest in 76 women who were induced after term. The enzyme levels in 117 women who developed hypertension of pregnancy were higher than for normotensives; the highest levels were found in 32 women with pre-eclampsia. A correlation was found between serum CAS activity at 36 weeks' gestation and the birth weight of babies of women who went into spontaneous labour at term (277 to 283 days' gestation).