By Tracy G. Cassels

“Failure to progress” – a term far too many women have heard during their birthing experience.  What does it mean?  It means your body isn’t dilating or getting your baby out based on a predetermined schedule.  What is this schedule?  It’s Friedman’s Curve, and it looks like this:


A depiction of Friedman’s curve, based on data from Friedman, E. A. (1955). “Primigravid labor; a graphicostatistical analysis.” Obstet Gynecol 6(6): 567-589. and Friedman, E. A. (1956). “Labor in multiparas; a graphicostatistical analysis.” Obstet Gynecol 8(6): 691-703.  From Evidence Based Birth.

The data is based on 500 labouring women from 1954.  There are many, many reasons why the curve itself is out of date and a wonderful article from Evidence Based Birth (found here) on the topic is incredible and in all seriousness, go read it because it’s unbelievably comprehensive.  But it misses one thing that I want to add and address:  How we think of averages.

Based on Friedman’s curve, the amount of time to reach each stage is as follows:


 Time to reach (Standard Deviation)


 8.6 hrs (6 hrs)
4.9 hrs (4 hrs)
1 hr (0.8 hrs)

Now, although there are lots of reasons to ignore this data completely, what if we don’t?  What if we assume we could take 500 women today and get the same results (which we probably wouldn’t for reasons EBB provides)?  What does this mean?

Well, if we think of it statistically,  the amount of time needed to define failure to progress should be based on the top 5% of births which is the equivalent of a standard deviation of 1.65.  Before we calculate it, let’s just remember that birth falls on a normal curve as well which looks like this:

normal curve

Okay, so for a woman to have not progressed based on being in the top 5%, she would need to have taken 18.5 hours to get to 4cm dilation or 11.5 hours to get from 4 to 10cm dilation or have been pushing for 2.32 hours (a woman at the edge could take 32.32 hours and have it be in the “normal” realm).  I don’t know about you, but when a doctor first came in to suggest I wasn’t progressing fast enough during the pushing stage, I’d only been pushing an hour.   At an hour, 50% of women will have finished pushing and are hopefully holding their babies.  But 50% of women are still pushing.  And for those who are told they aren’t progressing after 8 hours of early labour, there’s not a single shred of evidence to suggest that.  In fact, based on old data, 40% of women wouldn’t have reached 4cm after 10 hours.

The problem is when people assume that because a number is an average, most people will fall towards that.  It’s nothing of the sort.  It’s just a mid-point with people falling on both sides equally and sometimes falling rather far away while still being completely normal.  When it comes to birth and the potential for problems, we usually err on the side of caution, but if we err too far to the side, we end up with problems, like rocketing c-section rates and the complications that go along with those.  Or myriad interventions that aren’t called for.

We need to be very clear when we start throwing around the term “failure to progress” that we should be talking about a very specific limit barring no other problems.  It can be serious and a symptom of other complications that need dealing with, but not at the stages a lot of women are being told they’ve hit it.  Let’s also not forget the current standards don’t even consider that we need updated data on averages based on current birthing practices (e.g., with and without an epidural, first time versus experienced birthers).  And for mothers, if you think you’re going into birth with an “average” total labour and pushing time of 12 hours, think again.  You could labour for 3 hours or 32 and still fall in the range of what’s normal.