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Understanding the data around induction and being overdue

The Facts Around Induction


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23/09/2017

Understanding the data around induction and being overdue

Inductions are one of the most common interventions that women experience during birth; and the rate of inductions carried out in Australia is slowly climbing higher.

If you are faced with an induction the first important question to ask is why? and then dig a bit deeper to see if the reason for induction is justified. So, what determines a valid reason for inducing labour? The answer lies in doing some research and then weighing up the pros and cons for yourself.

A medically indicated Induction may be needed for complications such as as pre-eclampsia, failure to thrive (FTT) or faltering weight of the baby and/or concern about the mother's health. However, the other common reason for inductions that we are seeing these days is for 'prolonged pregnancy' i.e. being overdue.

Rachel Reed from MidwifeThinking lays out the pros and cons of induction because of prolonged pregnancy:

Understanding Risk

"I don’t particularly like the concept of ‘risk’ in birth. There are all kinds of problems associated with providing care based on risk rather than on individual women. However, risk along with ‘due dates’ is here to stay, and women usually want to know about risks. Risk is a very personal concept and different women will consider different risks to be significant to them. Everything we do in life involves risk. So when considering whether to do X or Y there is no ‘risk free’ option.

All women can do is choose the option with the risks they are most willing to take. However, in order to make a decision women need adequate information about the risks involved in each option. If a health care provider fails to provide adequate information they could be faced with legal action. Induction for prolonged pregnancy is not right or wrong if the choice is made by a woman who has an understanding of all the options and associated risks."

The Risks of Waiting

"In theory, after term (i.e. 42 weeks) the placenta starts to shut down. There is no evidence to support this notion. There is also a good physiological explanation of the development and ageing of the placenta, which concludes that: 'There is, in fact, no logical reason for believing that the placenta, which is a fetal organ, should age while the other fetal organs do not…' I have seen signs of placental shut down (ie. calcification) in placentas at 37 weeks and I have seen big juicy healthy placentas at 43 weeks. There is also the idea that the baby will grow huge and the skull will calcify making moulding (when the bones in the baby’s skull adjust), and therefore birth difficult. Again there is no evidence to support this theory and babies are pretty good at finding their way out of their mother's expandable pelvis. It is interesting that these two common assumptions about post-term pregnancy contradict each other. If the placenta stops functioning, how does the baby continue to grow so well?

The real concern with waiting beyond 41 weeks is the increased chance of the baby dying (perinatal death). And women need these statistics in order to make an informed decision. A Cochrane review summarises the quantitative research examining induction versus waiting: 'There were fewer baby deaths when a labour induction policy was implemented after 41 completed weeks or later.' However, it goes on to say: '…such deaths were rare with either policy…the absolute risk is extremely small. Women should be appropriately counseled on both the relative and absolute risks.'

Essentially, according to the available research, if you are induced at 41 weeks your baby is less likely to die during, or soon after birth. However, the chance of your baby dying is small either way – less than 1% or 30 out of every 10,000 for those waiting versus 3 in every 10,000 for those induced. This research article reports the relative and absolute risk of stillbirth at various gestations with waiting vs induction. The authors state that 1476 women would need to have an induction to prevent 1 stillbirth at 41 weeks gestation. The substantial increase in risk occurs at 42 week onwards with a stillbirth rate of 1 in 1000 (Decker 2016).

Reviews are only as good as the research they review and there are some concerns about the quality of the available research. The World Health Organization (WHO) recommends induction after 41 weeks based on this review but acknowledges the evidence is “low-quality evidence. Weak recommendation”.  Another review of the literature in the Journal of Perinatal Medicine (Mandruzzato et al. 2010) concluded: “It is not possible to give a specific gestational age at which an otherwise uncomplicated pregnancy should be induced.”

One of the main problems with quantitative research is that it rarely answers the question why, and rather focuses on what (happens). For example, congenital abnormalities of the baby and placenta are associated with post-term pregnancy and this may account for the increased risk rather than the length of gestation (Mandruzzato et al. 2010). Quantitative research also takes a general perspective rather than addressing the risk for an individual woman in a particular situation. For example, is the prolonged pregnancy as sign of pathology or does this woman come from a family of women who have a longer gestation timeframe?

Anyhow – to pretend there are no risks associated with prolonged pregnancy (in general) is not helpful for women trying to make decisions about their options. These general risks should be part of the information a woman uses to decide what is best for her. "

The Risks Associated With the Induction Procedure

"The induction process is a fairly invasive procedure which usually involves some or all of the following. There are a number of minor side effects associated with these medications/procedures (eg. nausea, discomfort etc.) There are also some major risks:

  • Prostaglandins (prostin E2 or cervidil) to ripen the cervix – may lead to hyperstimulation resulting in fetal distress and c-section;
  • Rupturing the membranes – may lead to fetal distress and c-section;
  • IV syntocinon / pitocin – may lead to (mother) rupture of uterus; post partum haemorrhage; water intoxication leading to convulsions, coma and/or death; reduced breastfeeding rates; increased postpartum depression/anxiety; and (baby) – hypoxic brain damage; neonatal jaundice; neonatal retinal haemorrhage; death. There is also research suggesting that there may be a link between the use of syntocinon/pitocin for induction and ADHD (Gregory et al. 2013; Kurth & Haussmann 2011). For mothers syntocinon/pitocin is associated with reduced breastfeeding and increased depression and anxiety at 2 months postpartum (Gu et al. 2015).

The most extreme of these risks are rare, but fetal distress and c-section are fairly common. The potential effects of uterine hyperstimulation on the baby are well known (Simpson & James 2008) – which is why continuous fetal monitoring is recommended during induction. This may also explain the association between induction and cerebral palsy (Elkamil et al. 2010)"

Considering the Woman's Experience of an Induced Labour.

"Induced labour is usually more painful than a physiological labour. Syntocinon produces strong contractions often without the gentle build up and endorphin release of natural contractions. In addition unlike natural oxytocin, syntocinon does not cross the blood-brain barrier to create the spaced-out, relaxed feelings that help women to cope with pain.

Not surprisingly, first time mothers are more than 3x more likely to opt for an epidural (Selo-Ojeme et al. 2011) during an induction. A Cochrane review found that: 'Women who used epidurals were more likely to have a longer delivery (second stage of labour), needed their labour contractions stimulated with oxytocin, experienced very low blood pressure, were unable to move for a period of time after the birth (motor blockage), had problems passing urine (fluid retention) and suffered fever and association between epidural analgesia and instrumental birth.' The review also found an increased risk of instrumental delivery and c-section for fetal distress with an epidural.

Summing it All up

"A significant minority of babies will not be born by 41 weeks gestation. Whilst the definition of a prolonged pregnancy is 42 weeks+, induction is usually suggested during the 41st week. Women need to be given adequate information about the risks and benefits involved with either waiting or inducing in order to make the choice that is right for them. There is no risk-free option. The risk of perinatal death is extremely small for both options. I know women who have lost a baby in the 41st week of pregnancy, and women who have lost a baby as a result of the induction process. For first-time mothers the induction process poses particular risks for themselves and their babies. Each individual woman must decide which set of risks she is most willing to take – and be supported in her choice."

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