The objective of this study was to determine the reliability of maternal perception of uterine contractions and the influence of gestational age and maternal training on the perception level. Three hundred fifty patients at high risk for preterm delivery were followed from 20 to 35 weeks of gestation. The average maternal perception (79%) of contractions did not significantly vary as a function of gestational age. Four groups of women were identified according to the perception index (PI) defined as the ratio of contractions felt by the mother and the contractions documented by tocodynamometer. Within each group, the PI did not significantly vary during consecutive monitoring sessions, as the women become more familiar with self detection of uterine contractions (R < .65, P > .95). Twenty-one percent (+/-5%) of all preterm uterine contractions were not perceived by the pregnant women from 21 to 35 weeks. Thirty-two patients (9.1%) fail to perceive most or all uterine contractions while 189 (54%) detect most or all at any time during the study period.