A further difficulty is how to define the onset of labour. As discussed in Chapter 36, the timing is important as it allows decisions to be made about the progress and ongoing management of labour yet it is difficult to establish with accuracy. Gibb (1988) discusses the concept of pre-labour, meaning the changes that occur in the last few weeks of pregnancy. It is often difficult to decide when the transition from the painless uterine contractions of pre-labour develops into true labour. This is reiterated by Simkin & Ancheta (2005), who argue that most slow labours do progress into normal labour patterns so it is difficult to accurately state that a labour is dysfunctional until the active phase. A slow labour before women become established is sometimes referred to as a ‘hesitant labour’.

The uterine contractions are weak and short and there is slow dilatation or no dilatation of the cervix. The woman does not find the contractions too painful or distressing. The fetus remains in good condition. If hypotonic contractions occur from the commencement of labour, they are said to be primary. The cause of primary hypotonic uterine action is unknown but is more commonly seen in primigravidae. If they begin after a period of normal uterine action, they are said to be secondary and there may be abnormalities of labour such as CPD, malposition of the occiput, a malpresentation, maternal dehydration or ketosis. The commencement of epidural analgesia sometimes causes hypotonic uterine action (Church & Hodgson 2004) due to the relaxation of the pelvic floor, which interferes with the mechanisms of labour.

There is loss of polarity and an increase in resting tone of the uterus. The contractions are frequent and painful and the woman feels pain between contractions. The woman feels the contraction before and after it is palpable abdominally. The cervix dilates slowly or not at all. Placental blood flow is decreased, which might lead to fetal distress. This type of uterine action is associated with malpositions of the occiput. If there is not maternal problems or fetal distress it is important to alleviate the woman’s anxiety and try mobilisation first, which might aid progress in labour prior to active management and introduction of interventions (Church & Hodgson 2004).

A Syntocinon infusion is used to manage prolonged labour when progress is slow but otherwise normal. This is acceleration or augmentation of labour. Once delay has been diagnosed and abnormalities of presentation or CPD ruled out, the membranes are ruptured and an intravenous infusion of Syntocinon is commenced to stimulate labour contractions. Any abnormality of fluid and electrolyte balance is corrected and both mother and fetus are monitored carefully. Adequate pain relief should be provided. Findings regarding the progress of labour should be recorded graphically on a partogram (Fig. 41.1) so that deviations from normal can be immediately recognised. There should be good psychological support of the woman. This should include explanation of what is happening and reassurance that everything is going as planned.

The condition of mother and fetus should be carefully assessed and as long as progress is being made, although slowly, more time may be given. Adopting an upright position, kneeling, standing or squatting may enlarge the pelvic outlet (Simkin & Ancheta 2005) and direct the presenting part against the posterior vaginal wall, utilising Ferguson’s reflex with the release of oxytocin. If the maternal or fetal condition becomes worrying or there is no obvious progress, an assisted vaginal delivery or, more rarely, a caesarean section may be needed.

A precipitate labour occurs when the uterine contractions occur frequently and are intense. There is rapid completion of the first and second stages of labour and delivery normally occurs within an hour. This condition is much more common in the multigravid woman and is usually caused by lack of resistance of the maternal soft tissues. There may have been minimal pain in the first stage of labour and the woman becomes aware of imminent delivery when the head is about to be born.

Administration of facial oxygen was common practice; however, there is no evidence to support either prophylaxis or short-term use of oxygen for fetal compromise (Fawole & Hofmeyr 2003, NICE 2008).

Cervical dystocia, where the cervix dilates slowly if at all, may be congenital or acquired. Congenital problems may be fibrosis, stenosis or poor cervical development. Acquired cervical dystocia may be due to fibrosis and scarring of the cervix following surgery, cautery or irradiation. In the past when there was failure to recognise the condition, prolonged pressure would result in ischaemia and there would be annular detachment of the cervix.