Induction of labour

Reasons for induction of labour may be classified into maternal and foetal.

Maternal reasons:

• infection
• pre-existing medical conditions e.g. diabetes, cardiac valve disease, pre-eclampsia, renal disease, liver disease, autoimmune disorders
• social reasons and maternal expectations

Foetal reasons:

• severe pre-eclampsia
• diabetes
• rhesus disease
• foetal infection
• IUGR
• postmaturity
• when prenatal investigations discover a condition requiring immediate post-natal therapy - e.g. a foetus with a diaphrahmatic hernia might be induced on a day when the paediatric sugeons have a list

NICE have suggested that (1):

Induction of labour to prevent prolonged pregnancy

• explain to women that labour usually starts naturally before 42+0 weeks, based on the gestational age estimated by their dating scan
• explain to women that some risks associated with a pregnancy continuing beyond 41+0 weeks may increase over time and these include:
  • increased likelihood of caesarean birth
  • increased likelihood of the baby needing admission to a neonatal intensive care unit
  • increased likelihood of stillbirth and neonatal death
• discuss with women that induction of labour from 41+0 weeks may reduce these risks, but that they will also need to consider the impact of induction on
• if a woman chooses not to have induction of labour, her decision should be respected. Healthcare professionals should discuss the woman's care with her from then on their birth experience
• be aware that, according to the 2020 MBRRACE-UK report on perinatal mortality, women from some minority ethnic backgrounds or who live in deprived areas have an increased risk of stillbirth and may benefit from closer monitoring and additional support. The report showed that across all births (not just those induced):
• compared with white babies (34/10,000), the stillbirth rate is
  • more than twice as high in black babies (74/10,000)
  • around 50% higher in Asian babies (53/10,000)
• the stillbirth rate increases according to the level of deprivation in the area the mother lives in, with almost twice as many stillbirths for women living in the most deprived areas (47/10,000) compared with the least deprived areas (26/10,000)
• discuss with women who choose not to have their labour induced if they wish to have additional fetal monitoring from 42 weeks. Advise women that:
  • monitoring only gives a snapshot of the current situation, and cannot predict reliably any changes after monitoring ends, but provides information on how their baby is at the moment and so may help them make a decision on options for birth
  • adverse effects on the baby (including stillbirth), and when these events might happen, cannot be predicted reliably or prevented even with monitoring
  • fetal monitoring might consist of twice-weekly cardiotocography and ultrasound estimation of maximum amniotic pool depth

Preterm prelabour rupture of membranes

• if a woman has preterm prelabour rupture of membranes, do not carry out induction of labour before 34+0 weeks unless there are additional obstetric indications (for example, infection or fetal compromise).
  • offer expectant management until 37+0 weeks
• if a woman has preterm prelabour rupture of membranes after 34+0 weeks, but before 37+0 weeks, discuss the options of expectant management until 37+0 weeks or induction of labour with her. When making a shared decision, take into consideration the following factors:
  • risks to the woman (for example, sepsis, possible need for caesarean birth)
  • risks to the baby (for example, sepsis, problems relating to preterm birth)
  • local availability of neonatal intensive care facilities
  • the woman's individual circumstances and her preferences
• if a woman has preterm prelabour rupture of membranes after 34+0 weeks (but before 37+0 weeks), and has had a positive group B streptococcus test at any time in their current pregnancy, offer immediate induction of labour or caesarean birth

Prelabour rupture of membranes at term

Offer women with prelabour rupture of membranes at term (at or after 37+0 weeks) a choice of:

• expectant management for up to 24 hours, or
• induction of labour as soon as possible.

For women who choose expectant management after prelabour rupture of the membranes at term (at or after 37+0 weeks), offer induction of labour if labour has not started naturally after approximately 24 hours

If a woman has prelabour rupture of membranes at term (at or after 37+0 weeks) and has had a positive group B streptococcus test at any time in their current pregnancy, offer immediate induction of labour or caesarean birth

Previous caesarean section

• if delivery is indicated, women who have had a previous caesarean section may be offered induction of labour with vaginal PGE26, caesarean section or expectant management on an individual basis, taking into account the woman's circumstances and wishes. Women should be informed of the following risks with induction of labour:
  • increased risk of need for emergency caesarean section during induced labour
  • increased risk of uterine rupture
  • the methods used for induction of labour will be guided by the need to reduce these risks

Maternal request

• induction of labour should not routinely be offered on maternal request alone. However, under exceptional circumstances (for example, if the woman's partner is soon to be posted abroad with the armed forces), induction may be considered at or after 40 weeks.

Breech presentation

• Induction of labour is not generally recommended if a woman's baby is in the breech presentation
• consider induction of labour for babies in the breech position if:
  • birth needs to be expedited, and
  • external cephalic version is unsuccessful, declined or contraindicated, and
  • the woman chooses not to have a planned caesarean birth.

Fetal growth restriction

• do not induce labour if there is fetal growth restriction with confirmed fetal compromise. Offer caesarean birth instead ****

History of precipitate labour

• induction of labour to avoid a birth unattended by healthcare professionals should not be routinely offered to women with a history of precipitate labour

Intrauterine fetal death

• in the event of an intrauterine fetal death, healthcare professionals should offer support to help women and their partners and/or family cope with the emotional and physical consequences of the death. This should include offering information about specialist support
• in the event of an intrauterine fetal death, if the woman appears to be physically well, her membranes are intact and there is no evidence of infection or bleeding, she should be offered a choice of immediate induction of labour or expectant management, and respect the woman's decision
• in the event of an intrauterine fetal death, if there is evidence of ruptured membranes, infection or bleeding, offer immediate induction of labour or caesarean birth
• intrauterine fetal death - women with a non-scarred uterus
  • If a woman with an intrauterine fetal death chooses an induced labour, offer:
    • oral mifepristone 200 mg followed by vaginal dinoprostone or oral or vaginal misoprostol. Base the choice and dosage of drug used on clinical circumstances and national protocols, or
    • a mechanical method of induction
• intrauterine fetal death - women who have had a previous caesarean birth
  • Advise women who have intrauterine fetal death, and who have had a previous lower segment caesarean birth, that:
    • induction of labour could lead to an increased risk of uterine rupture
    • the methods used for induction of labour will be guided by the need to reduce these risks (for example, by using mechanical methods)
    • some methods used for induction of labour may not be suitable (for example, both dinoprostone and misoprostol are contraindicated in women with a uterine scar)

Suspected fetal macrosomia

• options for birth are expectant management, induction of labour or caesarean birth
• there is uncertainty about the benefits and risks of induction of labour compared to expectant management, but:
  • with induction of labour the risk of shoulder dystocia reduced compared with expectant management
  • with induction of labour the risk of third- or fourth- degree perineal tears is increased compared with expectant management
  • there is evidence that the risk of perinatal death, brachial plexus injuries in the baby, or the need for emergency caesarean birth is the same between the 2 options
  • will also need to consider the impact of induction on their birth experience and on their baby

Notes (1):

• membrane sweeping involves the examining finger passing through the cervix to rotate against the wall of the uterus, to separate the chorionic membrane from the decidua. If the cervix will not admit a finger, massaging around the cervix in the vaginal fornices may achieve a similar effect
  • in their guidance (1) NICE note that membrane sweeping might make it more likely that labour will start without the need for additional pharmacological or mechanical methods of induction
  • Bishop score is a group of measurements made by doing a vaginal examination, and is based on the station, dilation, effacement (or length), position and consistency of the cervix
    • a score of eight or more generally indicates that the cervix is ripe, or 'favourable' - when there is a high chance of spontaneous labour, or response to interventions made to induce labour
• membrane sweeping
  • at antenatal visits after 39+0 weeks, discuss with women if they would like a vaginal examination for membrane sweeping, and if so obtain verbal consent from them before carrying out the membrane sweep
  • discuss with women whether they would like to have additional membrane sweeping if labour does not start spontaneously following the first sweep
• pharmacological and mechanical methods
  • discuss with women the risks and benefits of different methods to induce labour. Include that:
    • both dinoprostone and misoprostol can cause hyperstimulation
      • hyperstimulation is overactivity of the uterus as a result of induction of labour
        • is variously defined as uterine tachysystole (more than 5 contractions per 10 minutes for at least 20 minutes) and uterine hypersystole/hypertonicity (a contraction lasting at least 2 minutes)
        • may or may not be associated with changes in the fetal heart rate pattern (persistent decelerations, tachycardia or increased/decreased short term variability)
    • when using pharmacological methods of induction, uterine activity and fetal condition must be monitored regularly
    • if hyperstimulation does occur, the induction treatment will be stopped by giving no further medication, or by removal of vaginally administered products when possible
    • there are differences in the ease with which different vaginal products can be removed (for example, dinoprostone controlled-release vaginal delivery systems can be more easily removed than gel or vaginal tablets)
    • hyperstimulation can be treated with tocolysis, but hyperstimulation caused by misoprostol may be more difficult to reverse
    • mechanical methods are less likely to cause hyperstimulation than pharmacological methods
  • for women with a Bishop score of 6 or less, offer induction of labour with dinoprostone as vaginal tablet, vaginal gel or controlled-release vaginal delivery system or with low dose (25 microgram) oral misoprostol tablets
  • for women with a Bishop score of 6 or less, consider a mechanical method to induce labour (for example, a balloon catheter or osmotic cervical dilator) if:
    • pharmacological methods are not suitable (for example, in women with a higher risk of, or from, hyperstimulation, or those who have had a previous caesarean birth), or
    • the woman chooses to use a mechanical method
  • for women with a Bishop score of more than 6, offer induction of labour with amniotomy and an intravenous oxytocin infusion
    • advise women that they can have an amniotomy and can choose whether or not to have an oxytocin infusion, or can delay starting this, but that this may mean labour takes longer and there may be an increased risk of neonatal infection

Reference:

• (1) NICE (November 2021). Induction of labour.