Uterine contraction regularity during labour in White and Black patients

Irregularity of uterine contractions during labour was compared in 50 White and 50 Black patients. The standard deviation of distances between contractions as seen on cardiotocography and of maximal pressures was used to compare contraction regularity in the two groups of patients. A small standard deviation (SD) indicated regular contractions; a larger SD signified irregular contractions. Mean SDs of peak-to-peak and of base-to-base measurements were both 6,3 mm for White patients and both 7,6 mm for Black patients. The mean SD for maximal uterine pressures was 9,5 mmHg for White patients but 12,7 mmHg for Black patients. All these differences were statistically highly significant, and this implies that uterine contractions are more irregular in Black patients.