Creatine kinase (EC-No.2.7.3.2) and creatine kinase isoenzymes during pregnancy and labor and in the cord blood.

Total CK and CK isoenzyme activity in serum was investigated during pregnancy, labor and after delivery as well as in cord blood. Total CK was decreased in the second trimester of pregnancy but increased in late pregnancy. Low CK-MB activity in serum was found in patients with early labor pains. CK-BB activity could never be detected during pregnancy. Total CK and isoenzyme activity increased after delivery. The rise of total CK and CK-MB in maternal serum is directly correlated with the following: type of delivery, duration of labor, parity of the mother, and birth weight. From this it can be deduced that postpartum CK levels depend on skeletal muscle activity as well as on the activity of uterine muscle. Prematures and infants "small for date" have significantly lower total CK and slightly more elevated CK-BB activity in cord blood than children of normal maturity. CK-BB activity is much more pronounced in high risk patients with low Apgar score.