Induction of Labour
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Introduction
In different mammals, signals from either the mother or the fetus can induce labour. We do not know what the trigger is in humans, though some possibilities include:
Prostaglandins (PGE2 and PGF2alpha) are produced in the endometrium, myometrium, and chorioaminon, and levels increase near term and further in labour. PGE2 is associated with cervical ripening due to collagen lysis and water accumulation.
PGE2 analogue dinoprostone and PGE1 analogue misoprostol are used as cervical ripening agents.
Oxytocin receptors in the uterus increase in number as term approaches, but serum levels increase siginificantly only once labour has begun.
- synthetically used to induce or augment labour, but first the cervix needs to be ripe or induction will not work
Induction of labour is another use for oxytocin, in which prostaglandin PGE2 may also be used.
SOGC Clinical Practice Guideline 2001 suggests we use the minimum dose to achieve active labour, that dose intervals are no less that 30 min, and that reassessment is reasonable once a dose of 20 mU/ml is reached.
ACOG Practice Bullitin 10 1999 (2006) supports both low and high dose protocols.
RCOG (NICE guidelines) 2008 - IV oxytocin alone should not be used for induction of labour. Amniotomy and oxytocin should not be used as a primary method unless there are specific contraindications to the use of PGE2. This is due to its increased invasiveness, increased discomfort, and increased risk of uterine hyperstimulation.
Indications
Clinical Usage and Tips
Procedure
Risk Factors
Adverse Events
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