Constancy of serum angiotensin-converting enzyme activity in normal and complicated pregnancy

Angiotensin-converting enzyme occupies a central position in the dynamics of the renin-angiotensin system. We prospectively studied serum angiotensin-converting enzyme activity in 112 women at various stages of pregnancy and in the postpartum period because converting enzyme levels have not been well documented in pregnant women with medical disorders which might be expected to influence intravascular volume or blood pressure. Enzyme activity is lower during pregnancy than it is in the same population at 6 weeks postpartum. Levels of serum angiotensin converting enzyme activity remain relatively stable during gestation but drop during the immediate postpartum period. Diabetes, chronic hypertension, and pregnancy induced hypertension fo not markedly change serum angiotensin converting enzyme activity.