C H A P T E R 1 9 Prolonged pregnancy and disorders of uterine action

1. C H A P T E R 1 9Prolonged pregnancy and disorders of uterine action

2. This chapter examines the evidence relating to prolonged pregnancy,induction of labour, prolonged labour and precipitate labour. Any decision with regards to the management of a pregnancy that continues beyond term is based on discussion between the woman and obstetrician, but the midwife is in a unique position to help the woman make sense of

3. such discussions, thereby enabling her to make an informed decision based on informed choice. • When labour is induced, when there is failure to progress in labour or when labour is prolonged, with or without further complications, the midwife remains in a key position to ensure the woman is kept care of the woman will be discussed throughout.

4. informed so that she is enabled to continue to exercise her ability to be autonomous in the plan of care of her own labour and birth and the execution of that plan.

5. The chapter aim s to: • explore the issues relating to prolonged pregnancy with reference to research and other evidence. • outline the indications for the induction of labour and examine the methods used to induce labour in contemporary practice • describe the process where there is perceived failure to progress in labour or labour is prolonged and review the current evidence

6. used to support the management and care in such cases • describe the serious complication that is obstructed labour and discuss the importance of competent midwifery management and care of women during the antenatal and intrapartum period if such complications are to be avoided • highlight the significant events in a precipitate labour.

7. Prolonged pregnancy • on pregnancies that go beyond the expected date of birth (EDB) and more specifically beyond 42 weeks (294 days) lies in the terms used to describe such pregnancies such as post-term pregnancy, prolonged pregnancy and postdates.

8. According to post- term pregnancy is defined as a pregnancy where the gestation exceeds 42 completed weeks (294 days). as both post-term and postdate.

9. What is clear is that all these terms refer to a specific gestation of the pregnancy and not the fetus or neonate. For the purposes of this chapter the term prolonged pregnancy will be used to describe a pregnancy equal to or beyond 42 weeks. Postmaturity refers to a description of the neonate with peeling of the epidermis, long nails, loose skin suggestive of recent weight loss and an alert face The relationship, if any, between prolonged pregnancy and postmaturity will be explored later in the chapter.

10. If prolonged pregnancy is defined by weeks of gestation, whether this is based on a calculation of the EDB using Naegele's rule or by ultrasound scan no later than 16 weeks, is to consider women as a homogenous group and neglects, among other things, the racial variations with shorter gestational age in South Asian and Black women If the anxiety pertaining to prolonged pregnancy is possible adverse neonatal

11. outcome then perhaps we need to consider how prolonged pregnancy is defined for these groups of women. suggest the notion of prolonged pregnancy as ‘a normal variation of human gestation’. According to only a small proportion of prolonged pregnancies have babies that are postmature as described above.

12. Incidence • the frequency or incidence of prolonged pregnancy is between 5% and 10%. • the number of women where EDB is uncertain and different induction policies Based on a definition of equal to or more than 42 weeks a true incidence of prolonged pregnancy is difficult to assess because in many cases women's labour is

13. induced before reaching that time for specific complications in the pregnancy, for maternal request or because the pregnancy has gone beyond the EDB.

14. The use of an early ultrasound scan to date the pregnancy whether or not there is uncertainty with the last menstrual period (LMP), is thought by many to reduce the number of pregnancies categorized as prolonged Both accurately defining prolonged pregnancy and the accurate dating of a pregnancy is important if the woman is to be advised appropriately regarding the possible risks when discussing the options of expectant management or IOL where pregnancy is prolonged in order to avoid unnecessary intervention in an otherwise ‘low-risk’ pregnancy.

15. Possible implications for mother, fetus and baby • increase in perinatal mortality and morbidity as the pregnancy goes beyond 41 weeks

16. if a pregnancy continues beyond 41 completed weeks the risks for the mother are associated with : • a large for gestational age • or macrosomic infant such as shoulder dystocia, • genital tract trauma, • operative birth

17. and postpartum haemorrhage (PPH). • with the risks of IOL, such as increased need for epidural anaesthesia, • uterine hyperstimulation, • operative birth, • PPH and • failed induction

18. the possible risks for the fetus and neonate in a prolonged pregnancy appear to be two-fold: placental dysfunction linked to oligohydramnios, • restricted fetal growth, • meconium aspiration, • asphyxia • and still birth; • conversely the cases where growth continues resulting in • a macrosomic infant at risk of bony injury, soft tissue trauma, hypoxia and cerebral haemorrhage.

19. suggests that the changes in the placenta over the course of pregnancy are part of a process of maturation and an increase in functional efficiency as opposed to a decrease in functional efficiency.

20. Given that few post-term neonates exhibit signs of postmaturity, possible changes in placental function might be more appropriately linked to pregnancies where the neonate displays such characteristics rather than in prolonged pregnancies