A study of the effect of meptazinol on fetal heart rate patterns.

A study was carried out in 40 women undergoing labour to investigate the effect of 100 to 150 mg meptazinol intramuscularly, given alone for the relief of labour pain, on fetal heart rate patterns. Patients were monitored continuously using a fetal scalp electrode attached to a fetal monitor, and fetal heart rate patterns recorded on the cardiotocograph. Traces were interpreted for 2 hours preceding and 2 hours after administration of meptazinol using a 12-point scoring system to quantify the variables of baseline rate and variability and the presence or absence of variable or late decelerations. All babies were born live and, except for 1 delivered by emergency caesaraen section under general anaesthesia, none had an Apgar score less than 8 at 1 minute. Analysis of the cardiotocograph traces showed that adverse changes, such as loss of variability, were not significantly associated with the use of meptazinol.