True or false: the risk of stillbirth is highest after 42 weeks

Time for a true or false… is the risk of stillbirth at its highest after 42 weeks? This isn’t a clear cut one to answer, but that in itself may surprise a lot of people who may assume the answer is plainly true.

As you approach 40 weeks, the discussion around induction of labour is likely to enter the conversation, and you may be told that you need to be booked in for an induction if you haven’t gone in to labour naturally by around 41 weeks to prevent risk to baby. But what IS the actual risk? What does the research say? And what IS the absolute risk of continuing with your pregnancy?

The research Various studies and meta-analyses have been carried out looking at the risks of expectant management (waiting for labour to start naturally) versus induction of labour. A Cochrane review published in 2018 found that the risk of stillbirth increased with the length of pregnancy, but that the risk of stillbirth was very low and that you would need to induce 426 women around 41 to 42 weeks to avoid one stillbirth (Middleton P. et al. May 2018).

However, there have been multiple other studies and reports which have shown that the risk of stillbirth post dates does not increase. The Confidential Enquiries reports (CESDI, CEMACH, CMACE and MBRRACE) include data collected over a period of 10 years from 20,000 people who continued with pregnancy post 42 weeks. These reports show the risk of stillbirth and neonatal death is lower at 42 weeks than it is for those who birth at term. Data collected from the Office for National Statistics ‘Birth Characteristics’ reports also backs this conclusion.

Another commonly cited research study is the ARRIVE trial which included just over 6,000 births. Although this study is arguably flawed because of the small sample size and potential selection bias, some findings are worth noting:

What did the ARRIVE trial find?
They found that inducing labor at 39 weeks did not improve the primary outcome of death or serious complications for babies. For mothers, induction at 39 weeks was linked to a lower rate of Cesarean compared to those assigned to expectant management.

Do you have to be induced after 42 weeks? No! It’s important to make an informed decision, weighing the following:

  • the potential risks of waiting for labour to start

  • the potential risks of the induction itself to you and to baby

  • the possible benefits of an induction

  • the benefits associated with letting labour start naturally

Legally no one can force you to be induced. They can make recommendations, but it’s your choice to consent or decline.

Where to go for more information:

This AIMS U.K. journal article contains a fantastic break down of the research and evidence around the associated risk of prolonging pregnancy:

“Labour Induction at Term – How great is the risk of refusing it?

AIMS Journal, 2019, Vol 31, No 1

Evidence based birth also has a very detailed in-depth review worth reading: “Evidence on: Inducing for Due Dates”

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