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Membranes usually rupture spontaneously towards the end of the first stage labour. But during the 1970s the advent of the partogram and the idea of the ‘active management of labour’ made artificial rupturing of membranes (ARM) common practice. This was seen as a useful way of ‘speeding things up’, being able to see the colour of the amniotic fluid and enabling the application of fetal scalp electrodes.

However, the artificial rupturing of membranes often results in more painful and distressing contractions. Women increasingly don’t want it to be done and midwives are also questioning its merits as a practice, stimulating further research.

Facts and fiction

Some research suggested that ARM could decrease the length of labour, but it was also associated with an increase in ‘fetal distress’, increased likelihood of caesarean section and greater need for analgesia.

Other evidence points to the physiological benefits that intact membranes provide in buffering the baby’s head from the intensity of the contractions. Protruding membranes also form a circular area of pressure over the cervix, which helps with its dilatation. This can be equally effective as the baby’s head in stimulating and stretching the cervix, but less aggressive. And it can be particularly helpful where a baby is presenting with a deflexed head.

A large trial conducted by the National Childbirth Trust found that the great majority of women found labour harder to cope with following amniotomy and felt the physiology of labour had been disturbed. Fortunately, the practice of performing ARM without a woman’s knowledge or agreement has given way to obtaining informed consent. But although we may now ask women for their consent, we need to ensure that they really do understand the implications. This communication should begin in pregnancy. We also need to be sure that there is a valid clinical reason for ARM.

Rupturing membranes not only commits you to delivery within a certain timeframe but also exposes the baby and woman to an increased risk of infection. This intervention can also cause an increase in pain, in some cases making labour unmanageable without analgesia - in turn, increasing the likelihood of further intervention. This can affect maternal psychological well-being, and delay the onset of maternal affection.

Routine amniotomy should therefore not be considered to be a part of normal labour.

Tips and tricks

• Ask yourself “Is rupturing membranes necessary in this case?” - what clinical reasons would you record to justify this course of action. Don’t have an amniohook near you

• Learn by observation - watch the character of the labour, and how the woman copes with it. What is the state of the baby? Is the baby born with a caput succedaneum or develops cephalhaematoma?

• Does your organization have a guideline on ARM? - if so, whose interests does it serve? Do you feel there is a more appropriate way this could be approached? Express your views to those involved in formulating policy. It is also useful to maintain a personal/team/unit audit of the number of ARMs performed, so that you can compare the number of women having normal births with and without ARM.

Further reading

Henderson C. Artificial rupture of the membranes. In Alexander J, Levy V, Roch S (eds) (1990). Intrapartum Care-A Research Based Approach. Macmillan Education, Hampshire

National Childbirth Trust (1989) Rupture of the Membranes in Labour: Women’s Views. National Childbirth Trust, London

Royal College of Midwives (2004) Evidence-based guidelines for midwifery-led care www.rcm.org.uk

Walkinshaw SA (1994) Is routine active intervention in spontaneous labour beneficial? Contemporary Review of Obstetrics & Gynaecology 6: 13-17