Going ‘overdue’

You tell anyone you’re pregnant, and after a broad smile and a flash of congratulations, you are asked the inevitable, predictable question, ‘When’s it due?’

There is only one answer to this: a very precise, one-in-365 date, the date at which it has been decided that you are exactly 40 weeks pregnant. On your notes, and in your head, that magical date becomes etched. Of course you know very well that almost no babies actually arrive on their due date, but it still becomes the focus of all forward planning in this pregnancy.

Then the date comes, and, the chances are, you’re still pregnant – 58% of women are still pregnant on their due date. You go to bed that night – still pregnant. You wake up in the morning – you’re still pregnant. Only now you are Overdue. And if you have the temerity to carry on being Still Pregnant for another seven days – between 19 and 24% of women are – you are plunged into the conundrum of whether or not to accept the induction that’s urged on the vast majority of postdates women.

Only, hang on a sec. The World Health Authority defines term pregnancy as 37 to 42 weeks after the last monthly period, so could it be that you’re not overdue at all? That anything up to 42 weeks is perfectly normal and nothing to worry about? How does that sit with the shroud-waving that might have begun – your baby is in trouble, your placenta is failing and you are doubling your chance of a stillbirth by choosing to continue the pregnancy?

This is where the can of worms is well and truly opened. In 2001 the National Institute for Clinical Excellence (NICE) published its guidelines on induction of labour which, based on the available evidence and very carefully researched, stated that a woman should be offered induction at 41 weeks pregnant, and that, if she declined such an offer, she could be monitored and levels of amniotic fluid would be checked after 42 weeks.

The research upon which the guidelines was based has since been rubbished; in 2002 Menticoglou and Hall stated in the British Journal of Gynaecology that, ‘the higher risk that routine induction at 41 weeks aims to reduce is dubious, if it exists at all.’

The argument rumbles on; most recently, in October 2006, another report published online at www.cochrane.org reiterated NICE’s suggestion that induction at 41 weeks appeared to prevent deaths.

Informed choice is always a good idea in maternity. Yet when it comes to postdates pregnancy, the information is all over the shop, mutually contradictory and confusing. Let’s take a look at some of the facts, while recognising that some of these are disputed, that surround a pregnancy at 41 weeks.

  • A woman who is 41 weeks pregnant has a 60% chance that she will labour spontaneously within the next three days, and a 90% chance that she will do so within the next seven days.
  • A baby at 41 weeks may be at a slightly higher risk of stillbirth than a baby at 40 weeks, but the data is not clear on this. What is undisputed is that a baby at 43 weeks has double the chance of stillbirth of a baby at 40 weeks – but that in both cases, the risk is miniscule: 0.2% compared with 0.4%. Some studies suggest that the risk is around 0.3% at 42 weeks, but we don’t know how the rates increase over the three weeks from 40 to 43 weeks.
  • If a baby is small-for-dates, the risks of stillbirth become higher. Some studies suggest that where a baby is of normal size, the risks up to 42 weeks are almost negligible.
  • Many studies suggest that induction at 41 weeks does not affect the rate of caesarean; some go further and suggest that neither does it affect the rate of assisted delivery (use of forceps or ventouse) or epidural.
  • Instinctively, however, many people dispute this: if an induced labour may be longer and more painful, they argue, how can it not affect the rate of interventions?

It’s all very well talking about 41 weeks, but for many women, they may end up with varying due dates (ie the date at which they are 40 weeks pregnant). These can depend on whether they are counting it from the first day of their last period, or from an early scan, which is widely accepted to be more accurate – NICE recommends a dating scan as one weapon in its armory to avoid the problem arising. The average discrepancy between the two dates is three days, and researchers in Sweden have therefore suggested that if the due date was considered to be 40+3 rather than 40+0, the early scan would no longer be necessary.

So, let’s imagine that you’re 41 weeks – which is, broadly speaking – the stage at which most NHS hospitals start suggesting induction (although the specific date varies according to hospital, and circumstances of the woman and the labour ward). You have two options: to go for the induction, or to decline it. Mary Newburn, Director of Policy for the NCT, says, ‘women can decline if they don’t want the treatment. There’s no need to make an immediate decision – they can review every few days if that’s what they want to do.’

An induction would begin with a stretch and sweep – where a midwife or doctor inserts a finger into the vagina to feel the cervix (neck of the womb), and, having stretched the cervix slightly open, sweeps the membranes (amniotic sac). This can result in the release of a flood of hormones which can, if you’re lucky, be enough to start labour off with no further intervention. Studies suggest that three sweeps on consecutive days is the most effective course of action. Some women report that sweeps are slightly uncomfortable. After a sweep you can go home and carry on as normal.

The next option is to insert a pessary of prostaglandin – one of the hormones associated with the onset of labour – into the vagina. Again, sometimes this is enough to start labour off with no further intervention, and can be repeated up to three times at 12 hour intervals. Generally you will be advised to stay in hospital once an induction with pessary has begun, although there have been occasions reported where women have been sent home after this procedure.

If neither the sweep nor the pessary has had an effect, the next step may be to rupture the membranes (waters), or to set up a drip of artificial hormones. Which step is taken varies from unit to unit and even from woman to woman. From here on, there’s no turning back – you are finally in labour and your baby is on its way! However, it may not be plain sailing, and once you are induced, continuous monitoring is strongly recommended (which in turn is believed to increase the rate of caesarean). Hertfordshire midwife Lynn Walcott says, ‘I think that an induced labour may well be more painful than a spontaneous one, particularly if the woman was not “ready”. But not necessarily: if the body was about to labour anyway – and in that case it’ll often take very little intervention to labour.’

The other option is to wait and see what happens. The NICE guidelines suggest that where women decline induction at 41 weeks, daily monitoring is offered from 42 weeks – but many hospitals will begin monitoring earlier than this anyway. Again, it is your choice whether or not you agree to daily monitoring. Later, a scan might be offered to assess the level of fluid that remains around your baby. There might also be the option of a Doppler Scan, which tests the functioning of the umbilical artery, although technology is still in its infancy.

There is some suggestion that the position of your baby – particularly one that is posterior – is likely to stay inside longer than an anterior baby. The neat solution to avoiding an unwanted induction here, then, is to practise optimal fetal positioning (OFP). Imagine that your uterus acts like a hammock, and the baby will lie on his or her back in that hammock. You want to make the hammock the front of your body, then, not the back – and to do that you need to lean forwards as much as possible, and avoid reclining positions. It’s not always that straightforward. ‘A posterior baby is more likely to go post dates,’ says Lynn Walcott. ‘I am, however, not convinced at the benefits or effectiveness of OFP.  There is much logic about it, but I am concerned at women blaming themselves if their baby does not get into the “right” position. Also, frankly, we do not always get it right on palpation! I believe that should a pregnancy go way beyond “dates” owing to OP position, all the same “rules” apply with regard to “is it ok?” – that is, closer surveillance of the pregnancy.’

There is no conclusion, then: no clear course of action that the research would state we should take. The arguments pro and con induction at 41 weeks are batted back and forth. Lynn Walcott: ‘If there was one intervention I would like to see ended, it’s induction of labour for post-dates! Independent midwives have an induction rate of around 2 per cent, versus a UK rate of over 20 per cent… what does that say to you? Choosing the best option is not dependent on risk or outcome, but, I believe, philosophy – individual circumstances and those of the people the woman surrounds herself with. This is especially true of induction.’




~ by Kedi Simpson on March 18, 2011.

5 Responses to “Going ‘overdue’”

  1. This is a piece I wrote for a magazine about three years ago. I still think it’s rather good, and worth sharing. The rate of induction for ‘post dates’ WHEN THERE IS NO OTHER INDICATION THAT THERE’S ANYTHING AMISS still bothers me!

  2. Both times, I was offered an induction date for bang on 42 weeks and not 41 weeks. During my labour, a student m/wife told me how she had declined an induction and went to 43 weeks. My husband asked her what colour her placenta was and she answered ‘grrey’. Not the best promotion!

  3. thank you (yet again!) Kedi for a well written peice putting things into plain English! You are rapidly becoming my childbirth Guru!

  4. I’ve just written an article that will be in the June edition of midwifery today on the issue that having a “due date” causes. It’s also one of my personal bug bears and so frequently skirted over.
    Thanks Kedi x

  5. Thanks for a very comprehensive & reassuring article from a fellow NCT teacher!

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