Intrapartum fetal heart rate patterns in pregnancies complicated by hypertension. A cohort study

Intrapartum fetal heart rate patterns were investigated in pregnancies complicated by hypertension in a cohort study. The total number of live births was 2400 and the frequency of hypertension was 8.8%. The study group comprised 2023 normotensive and 200 hypertensive deliveries. Dates of all pregnancies were established at an ultrasound examination in week 17. Ominous intrapartum fetal heart rate patterns were significantly more common in hypertensive deliveries than in normotensive deliveries (20.5% versus 7.6%). The women with hypertension were compared with a group of control women matched for age, parity, induction of labor, and gestational week (20.5% versus 6.5%). In hypertensive women ominous fetal heart rate tracings were frequently associated with primiparity, induced labor, epidural block, delivery of a growth-retarded fetus, and beta 1-adrenergic receptor blockers. Ominous fetal heart rate patterns were less common in hypertensive women without these risk factors; still the significant differences in comparison with normotensive women remained. The hypertensive pregnancies accounted for no less than 21.0% of all ominous intrapartum fetal heart rate patterns, whereas 13% of all cases of ominous intrapartum fetal heart rate patterns could be attributed to the excess frequency in hypertensive pregnancies.