Continues from previous page
What is abnormal labour?
To understand what is meant by the term "abnormal labour", one has to know what normal labour is. This can be described as a process of labour which lasts for an optimum length of time, neither too long nor too short, passes without causing undue distress to the mother, and the baby is delivered in good condition. Any departure from this can be termed an abnormal labour.
Many people will take issue with rapid labour being classified as abnormal. What is wrong with it?
Extremely rapid labour is potentially dangerous. This is because it can lead to injury to the baby because of its rapid passage through the birth canal. The injuries - especially to the brain - can be quite serious.
Very rapid labour (also termed "precipitate labour") may also lead to heavy, even dangerous bleeding after delivery (postpartum haemorrhage or PPH). There is also the fact that the labour may start when the mother is not in hospital, not even at home. She may therefore have no help, a potentially dangerous scenario. Rapid labour may also cause injuries to the birth canal. Nasty tears to the perineum have been known to result from precipitate labour.
What are the causes of prolonged labour?
Arguably, the most common cause of prolonged labour is inefficient contractions. If the contractions are weak, irregular or uncoordinated, they may be unable to facilitate dilatation of the cervix and push the baby further down the birth canal.
This problem is most often overcome by using an oxytocin infusion. Oxytocin is actually the natural chemical that is produced in the brain to stimulate contractions.
Are there any other causes of prolonged labour?
If the fetus is of above average size and if it is large relative to the size of the mother's pelvis, there is potential disproportion. If the disproportion is only slight, the strength of the contractions may overcome it. Sometimes, however, the disproportion is considerable and labour fails to progress beyond a certain point.
It is usually not easy to accurately predict that vaginal delivery is not achievable during labour. The realization that there was disproportion is usually retrospective after a prolonged labour culminating in a caesarean section.
Apart from size, are there any other fetal causes of prolonged labour?
Yes. An abnormal position of the baby's head can make for slow progress of labour.
Normally, the head will be facing downwards with the neck of the baby bent forward and the chin resting on the chest. If the head descends into the pelvis with the neck extended and facing upwards (‘star-gazing’), there could be trouble in the form of a protracted labour. This state of affairs increases the possibility of instrumental delivery (forceps or ventouse) or caesarean section.
Can the cervix be to blame in prolonged labour?
Yes. Occasionally, in spite of strong, regular contractions, the cervix does not continue to dilate beyond a certain point. In most cases, the cause of this is obscure.
Occasionally, the cervical resistance may be due to scarring resulting from previous surgery or injury.
When labour has been induced, it is important to ensure adequate cervical preparation before stimulating contractions. If contractions are stimulated before the cervix is ready (i.e. while it is still long, firm and closed), there is a risk that it may not dilate, a situation that could culminate in an otherwise unnecessary caesarean section. This is why application of prostaglandin preparations (gel, tablets or pessaries) is sometimes necessary before stimulating contractions.