Initiation of labour is a complex process that involves fetal-maternal communication. Although the mechanism of the initiation of preterm labour has not been elucidated fully, it may differ from that in normal labour. The aim of this research was to study the effect of amniotic fluid from term and preterm deliveries on human myometrial contractions. The amniotic fluid was obtained from 45 women, who underwent caesarean section preterm (18) and at term (27) for routine obstetric indications. The influence of preterm and term amniotic fluid on spontaneous and oxytocin stimulated by in vitro isometric myometrial contractions was evaluated. Repeated measured ANOVA was performed for statistical analysis. Amniotic fluid from preterm delivery successfully inhibits myometrial contractions stimulated by oxytocin, so it may play role in maintaining normal pregnancy and preventing preterm delivery.