The exact physiology for the initiation of labour is still not fully understood but is considered to be the result of several interactions within the woman and baby’s bodies as the baby approaches maturity. There are many physiological and biological changes that occur in the last weeks of   pregnancy which prepare both the woman and her baby for labour and supports the baby to be ready for the transition to life outside the uterus/womb.

Labour and birth can be ‘medically induced’ but this is generally only done when there is a medical/obstetric reason – such as high blood pressure or concerns about the baby’s welfare. The woman and her maternity practitioner have to balance the risks of induction of labour against the risk of continuing with the pregnancy when determining whether the labour should be induced.

The decision to induce labour requires a consultation with the obstetric service.

When starting an induction it can take from a few hours to a few days to get labour underway.  The date of induction does not mean that your baby will necessarily be born that day.

Induction of labour is a two stage process:

• Ripening of the cervix to prepare it for the change it needs to undergo to thin and open

and

• Bringing on of labour by stimulating contractions to start

One or more of the following methods to induce labour may be recommended for your situation;

• Stripping the membranes – also called a membrane sweep or stretch and sweep
• Breaking your water – also called an amniotomy or ARM (artificial rupture of the membranes)
• A balloon catheter – This is a small tube that is inserted through the cervix, and a tiny balloon inflated. The pressure of the balloon can assist in softening your cervix
• Inserting the hormone prostaglandin vaginally to help ripen the cervix or
• Giving  oral misoprostil regularly over a number of hours until able to break the waters or labour starts
• Giving the hormone oxytocin via an IV  to stimulate contractions – usually only given after the waters have been broken

• Induction of labour is an intervention – and if the woman’s body is not ready to labour – that can result in more interventions. Women who have their labours induced are more likely to need epidural for pain relief, forceps/ventouse or a caesarean section birth. Their babies are also more likely to be admitted to a neonatal intensive care unit.
• If your cervix is not ready for labour or if this is your first baby, there is a chance that starting the labour process can take a number of days. This may make a difference to how much and what type of pain relief you may need.
• Women and babies respond in different ways to the medications/hormones to try to start labour and sometimes your baby may not cope well with induced labour, or you experience too many contractions which may affect you and your baby. This means that the baby’s heart rate will need to be closely monitored.  Sometimes this needs to be continuous for the whole labour and may restrict your ability to move about or in some cases to use water during labour.
• When the first part of labour is actively managed by an induction, women /wāhine are more likely to experience a heavier blood loss after the birth.