Uterine activity in labour

Reproductive success, the birth of a healthy child, may be seen in mechanical terms as the uncomplicated filling, enlargement and subsequent emptying of the uterus: a quite remarkable organ. Much clinical activity by obstetricians concerns the need to prevent premature emptying of the uterus and in turn causing it to expel the fetus at the appropriate time. Many believe a successful conclusion preferably includes the expulsion of the fetus safely per via naturales. Currently concern is expressed in many countries about the increasing frequency of Caesarean birth. An understanding of uterine activity is important for effective management of several pregnancy complications. However, this thesis is restricted to the birth process itself: the intra partum period. Several investigations have documented uterine activity at various times. However, detailed analysis correlated with the various phases of labour had not been undertaken. Previous workers had omitted to study normal events before abnormal ones effectively working without a normal range. The progress of labour has to be understood within the context of the nature of its onset and subsequent documentation of dilatation of the uterine cervix on a partogram: a graphic representation of labour. Preliminary work was undertaken to clarify types of labour progress and subsequent outcome of the labour according to the cervical dilatation pattern (cervimetric progress). The next step complemented this with a study of intrauterine pressure changes and the evolution adequately undertaken bearing in mind the important variables of parity and actual cervical dilatation at the time. Uterine activity profiles during labour were generated and significant differences shown according to parity. Induced labour was then studied documenting comparative profiles and the cumulative uterine activity as labour progressed. This led to the development of the concept of the total uterine activity in labour reflecting the resistance to the fetus passing through the birth canal: the cervical and pelvic tissue resistance. These results may be applied in the rational management of difficult labours permitting the appropriate use of oxytocic drugs and providing the data to determine the appropriate use of Caesarean delivery.