Lactate dehydrogenase isoenzymes in human myometrium during pregnancy and labor

Myometrial lactate dehydrogenase isoenzymes were investigated in 32 pregnant women and in 21 women during labor. During pregnancy and labor the H-type LDH isoenzymes were found to preponderate in contrast to M-type LDH isoenzymes. Both H-LDH and M-LDH isoenzyme activities showed a tendency to increase in normal pregnancy. In severe pre-eclampsia and in chronic hypertension, the uterine M-LDH level decreased. In normal labor, M-LDH activity declined in both the uterine and the rectus abdominis muscles.