Sixty-six of 390 patients studied at LAC/USC Women's Hospital between 1970 and 1973 had positive oxytocin challenge tests (OCT). Twenty-four percent of patients who were allowed direct monitored labor after a positive OCT showed no late deceleration and must be assumed to have had false-positive tests. Patients with positive OCT's had significantly increased incidences of perinatal mord late deceleration in labor when compared to patients with no positive OCT. The combination of a positive OCT and abnormal 24-hour urinary estriol excretion should be considered ominous.

The effects of ritodrine hydrochloride were evaluated in 25 toxemic patients in active labor utilizing continuous electronic monitoring of fetal and maternal cardiovascular systems and uterine activity. Fetal scalp blood and free flowing maternal antecubital venous blood was obtained for pH, Po2, Pco2, base deficit and blood glucose determinations prior to and immediately following the study period. The initial ritodrine dose was 50 mug/min for 15 minutes. The dose was increased by 50 mug/min each 15 minutes until there was a clinically apparent reduction in uterine activity. Once this was accomplished, the infusion was maintained for 30 minutes. There was a consistent increase in the maternal heart rate (MHR) and a significant rise in fetal heart rate (FHR) late in the infusion and in the postinfusion period. There was a widening of the maternal pulse pressure mainly due to a reduction in diastolic pressure with little change in the mean blood pressure. Maternal and fetal pH decreased and base deficit increased during the study although the PO2 and PCO2 remained unchanged. Maternal and fetal blood glucose rose significantly following ritodrine infusion.

The effects of ritodrine hydrochloride were evaluated in 10 patients in active labor with continuous electronic monitoring of fetal and maternal cardiovascular systems and uterine activity. Ritodrine infused at 150 μg per minute significantly decreased uterine activity and increased maternal heart rate with only minimal blood pressure changes. During the period of increased maternal heart rate, nonspecific changes in the maternal electrocardiogram were noted and thought to be rate related. The drug has no demonstrable effect on the fetal heart rate, fetal electrocardiogram, or acid-base status. The effects of ritodrine hydrochloride were evaluated in 10 patients in active labor with continuous electronic monitoring of fetal and maternal cardiovascular systems and uterine activity. Ritodrine infused at 150 μg per minute significantly decreased uterine activity and increased maternal heart rate with only minimal blood pressure changes. During the period of increased maternal heart rate, nonspecific changes in the maternal electrocardiogram were noted and thought to be rate related. The drug has no demonstrable effect on the fetal heart rate, fetal electrocardiogram, or acid-base status.