Induction of Labour Update 2020: Induction for all at 39 weeks?

Written by

Rob Buist

Published on

Blog, Resources

It has long been an axiom of obstetrics that induction of labour increases your risk of undergoing a caesarean – hell even my information sheet on the topic says this. But is this really true? And increased compared to whom?

Well observational studies in this area show that if you compare two women in the birth suite at the same gestation and one is being induced and the other is in spontaneous labour (and all else is equal; baby size etc) then yes, absolutely, the woman in spontaneous labour has a lower risk of a Caesar than the woman being induced. No question. But let’s take a different – and possibly more relevant – scenario…

Let’s say two women having their first baby who are at 38+ weeks gestation (and again all else is equal) visit their obstetrician on the same morning and the first asks for her labour to be induced at 39+ weeks because her husband is playing in the Grand Final in a couple of weeks. The second woman says I don’t want to have my labour induced until the last possible moment (say after 41 weeks).

Now until a year or so ago I would have told the first woman that by being induced at 39+ weeks she is increasing her risk of a Caesar compared to, say, the second woman. But a couple of large high-quality clinical trials have shown this not to be true. These two studies – both published in the prestigious New England Journal of Medicine – have shown the following:

  • The first trial looked at women over 35 year of age having their first baby. It found that induction – compared to waiting and seeing – made no difference to the caesarean rate. It also found no difference in the rate of harm to babies around the time of birth between both groups.
  • The second trial looked at women of any age having their first baby. This study showed a significantly lower risk of caesarean birth WITH induction of labour (18.6% versus 22.2%) when compared to waiting.
  • Both trials essentially showed no differences in terms of adverse outcomes for babies (stillbirths, being born in poor condition, needing to go to the baby unit etc). The second trial showed a possible (i.e. not statistically significant) small reduction in the number of babies coming to harm around the time of birth.

These trials can be added to our prior knowledge which is that, in essence, induction of labour after 41 weeks gestation does not increase the risk of a Caesar in women of that gestation and it improves – by an admittedly small margin – outcomes for babies born at 41+ weeks (most of us would consider going beyond 42 unwise as the risk of harm to the baby definitely increases then.

It is very important that we all understand that – for a variety of reasons – induction of labour IS associated with a risk of a Caesar. We can overstimulate the uterus and cause fetal distress, we can break the waters and cause the umbilical cord to pop out or we can simply fail to get you into labour. However, (and this is the important bit) the magnitude of these risks is definitely not greater – and could even be lower – than the risk of a Caesar (for what ever reason) if your pregnancy continues.

So where does this leave us?

  • I’ve said it before and I will say it again. Fortunately, we give birth and practice obstetrics in an age – and place – where the risk of significant harm to mothers and babies is extremely low, whatever way we choose to give birth.
  • When compared to waiting and seeing induction of labour at 39+ weeks DOES NOT increase your overall risk of a Caesar. If anything, it reduces it.
  • Induction of labour MAY be associated with a slight reduction in the risk of babies being born in poor condition when compared to waiting and seeing. However, if this difference exists it is small.
  • The term “social induction” is pejorative and should not be used particularly given the state of the scientific evidence. The choice to be induced at 39+ weeks gestation should be available if women so wish. Equally women should not be strongly advised, coerced or otherwise Jedi mind tricked into an induction at 39+ weeks if they do not wish it and they and their baby are fine.



  1. Randomized Trial of Labor Induction in Women 35 Tears of Age or Older. Walker KF et al. N Engl J Med 374: 9; 813 –
  2. Labor Induction versus Expectant Management in Low-Risk Nulliparous Women. Grobman WA et al. N Engl J Med 397: 6; 513 –