Effects of hypertension on pregnancy monitoring and results. The effect of severity of hypertension on fetal heart rate tracing changes and neonatal outcomes was evaluated on all patients with hypertension seen in 1980 and 1981 (666 cases, 10% of the pregnant population) in the Chicago-Lying In Hospital. The patients were grouped according to severity of hypertension, and the fetal heart rate monitoring, drugs administered, mode of delivery, and neonatal outcome were analyzed. Half of the patients (326) had mild hypertension and 13% (87) had severe hypertension; the remainder (253) had moderate hypertension. There were 49% primiparous and 51% multiparous women. The diagnosis of preeclampsia was made in 76% of cases, and chronic hypertension in 19%. Only 12% of the total were premature by dates, but 47% of this group were among the severe group. Oxytocin was given to 50%, whereas delivery was spontaneous in 56% of cases, and by cesarean section in 22%. This was higher among the severe hypertension group (37%), and the prematurity rate was 47%. Nonstress testing was done in one third of cases and only nonreactivity was associated with neonatal death. Neonatal depression (Apgar score less than 6 at 5 minutes) was significantly associated with intrapartum fixed baseline and late decelerations; these were the best predictors of fetal outcome. The administration of magnesium sulfate, hydralazine, meperidine, or morphine did not predictably affect the fetal heart rate pattern. The perinatal mortality was 21% in the mild group and 36% and 138%, respectively, among moderate and severe cases of hypertension. Close antepartum and intrapartum surveillance, including proper fetal monitoring, should help to reduce risks for mother and fetus through timely intervention. 