Another study has added to our knowledge about induction of labour at or before 42 weeks of pregnancy.
This topic has been in the news probably more than any other pregnancy and childbirth related issue in recent months. I have also spent a lot of time debunking and challenging some of the spin that has been put on this issue. The latest study has been published by Rydahl et al (2019), and their study shows that the evidence isn’t nearly as clear-cut as some people and organisations would like us to believe.
Their paper is freely available and describes a cohort study based on data from women in Denmark (Rydahl et al 2019). They looked at what happened before and after the recommended timing of induction of labour was changed from 42 weeks of pregnancy to 41+3 weeks of pregnancy. Rydahl et al (2019) looked at lots of outcomes and compared what happened during the two time periods in which the different induction of labour protocols (or recommendations) were in place.
What did they find?
The researchers found that there were no differences in stillbirths, perinatal deaths or low Apgar scores, which are considered to be the most important short-term, physical outcomes. However, in the time period in which women were offered earlier induction, there were more inductions (which one would expect) and women experienced more interventions. Not just those which are part of the induction process, but other kinds as well. This isn’t new or particularly surprising; we know that intervention tends to lead to more intervention.
In Rydahl et al’s (2019) study, earlier induction of labour was also associated with an increase in uterine ruptures. The rate went from 2.6 per thousand to 4.2 per thousand. Again, this is not entirely surprising. Iduction of labour often involves the use of powerful drugs which stimulate the uterus to contract, and these can sometimes stimulate the uterus too much. But this finding is worrying, and serves as a reminder that induction of labour is associated with possible risks and negative consequences as well as possible benefits.
So what do the findings tell us about induction of labour at or before 42 weeks?
The findings of this study show that there was no advantage to bringing the nationally recommended induction date forward from 42 weeks to 41+3 weeks (Rydahl et al 2019). This will be a moot point in many areas of the world, as induction of labour is already recommended before 42 weeks weeks. But this data is still quite important right now, not least because of a Swedish study which recently made media headlines when it was stopped because of concerns about stillbirth. The fact that the Danish data shows that stillbirth rates did not differ between 41+3 and 42 weeks is significant for women’s decision making. It highlights the very uncertain nature of our knowledge in this area and the fact that there are more factors to take into account than population-level data which is not considered in the context of the individuals concerned.
Some people and organisations are calling for earlier and earlier induction, either as a population-level policy or in certain groups of women who are deemed to be at higher risk (often without good evidence that induction of labour will do anything to lessen the chance of a problem). But it is clear that there is more to this picture than they would have people believe.
Where do we go from here?
If you would like to know more about induction of labour, I have a whole page of resources on this website and a book which helps explain the issues and the evidence.
We need more than this, though.It is also really clear to me that we need to do more to help women and families understand this topic and the evidence that relates to it.
Rydahl E, Declerq E, Juhl M et al (2019). Routine induction in late-term pregnancies: follow-up of a Danish induction of labour paradigm. BMJ Open 9:12. https://bmjopen.bmj.com/content/9/12/e032815
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