Labour - Active Management and Induction

The active management of Labour was pioneered by K O'Driscoll in 1969,¹ as a means of reducing the number of prolonged labours. Its aim was to keep labour to less than 12 hours and operative delivery rates to a minimum. Even in diluted form it has been shown to be effective in reducing labouring time in randomised controlled trials.^2,3 It was originally designed for primiparous women with singleton pregnancies at term, in spontaneous labour.
It has been modified significantly over time, but the core principles remain:

Induction is the process of starting labour by uterine stimulation. It should be used when it is thought that the baby will be safer delivered than it is in utero. [Needs to be clearly distinguished from augmentation of labour, which is the enhancement of uterine contractions once labour has started.]
RCOG and NICE guidelines^10,11 define its use in clinical practice:

• It should be offered to women with healthy pregnancy after 41 weeks. Risk of stillbirth increases from 3/3000 at 42 weeks to 6/3000 at 43 weeks.
• It should be offered to women whose pregnancy is complicated by diabetes, before term.
• In women with pre labour ruptured membranes after 37 weeks,(6-19% of pregnancies), they should be given a choice of either immediate induction, or watchful waiting for up to maximum of 4 days.¹² 84% labour within 24 hours, increasing by a further 5% every 24 hours after. Beyond 4 days, risk of infection outweighs any potential benefit to mother or child.¹³

Commonest reasons for inducing labour are:

• Prolonged pregnancy - 70% of such cases are induced after 41 weeks often at the mother's request. Obstetrician will usually agree if cervix is ripe.
• Suspected fetal growth retardation
• Hypertension and pre-eclampsia; approx. 50% women with this problem are induced
• Planned time of delivery in best interests of baby e.g. cardiac abnormalities which may need immediate surgery after birth

Check prior to induction:

• Need to check lie and position of fetus
• Volume of amniotic fluid
• Tone of uterus
• Ripeness of cervix; this is best predictor of readiness for induction and can be scored using Bishop's system¹⁴: If score >8, probability of successful delivery with induction as same as spontaneous onset of labour.

Contraindications

These are the same as for vaginal delivery. Absolute contraindications include:

• Severe degree of placenta praevia
• Transverse fetal lie
• Severe cephalopelvic disproportion
• Cervix <4 on bishop's score - can be overcome by ripening with prostaglandins

Relative contraindications include:

• Active primary genital herpes infection
• High and floating fetal head (risk of cord prolapse)

Induction Procedure

Procedure should be fully discussed with mother; explaining technique to be used and any possible side effects and consequences of failure (caesarean section). She needs to give her informed consent, possibly in writing or if not a signed note made in the woman's records.

• Assess fetal maturity
• Recheck presentation and position of fetus just before induction

Methods used include:

• Membrane sweeping
• Prostaglandin gel or pessary
• Oxytocin with/ or without artificial rupture of membranes

Commonest method of induction in UK is placing prostaglandin gel or pessary high in vagina (not cervix). Drug is absorbed through vaginal and cervical epithelium and delivered to the uterus via the blood stream. Obstetrician or midwife should stay with women for 20-30 minutes with cardiotocographic monitoring of fetus in case of myometrial overreaction.

Complications of Induction

May fail and require caesarean section.
All the complications of a normal vaginal delivery, plus:

• Uterine hyperstimulation; fetal distress and hypoxic damage to the baby¹⁵
• Uterine rupture, especially in multiparous women
• Intrauterine infection with prolonged membrane rupture without delivery (less likely if labour occurs within 12 hours)
• Prolapsed cord can occur with first rush of amniotic fluid, if presenting part not well engaged
• Amniotic fluid embolism
• 1.5x increased risk of operative vaginal delivery and 1.8x increased risk of caesarean section