For many women, 'the purple line' appears during childbirth. This is how midwives use it.

This post contains nudity.

Traditionally, the birthing process was kept behind a veil of ‘secret women’s business’ type mystery and privacy.

Thankfully, in the 21st century we realise that this approach has been helpful to precisely no one. 

We are now encouraged to find out everything there is to know about childbirth from the experts accompanying us on our pregnancy journey, as well as books, informative websites and support groups.

Watch: Questions about childbirth answered by mums and non-mums. Post continues below.

It is therefore pretty surprising to read something that relates to childbirth that even after having two kids of my own, I knew nothing about.

I refer to the purple line that can appear down a woman’s butt crack when she is in labour.

This line doesn’t just show up for fun like a stretch mark – oh no. It can actually be used by midwives as an indicator for how your labour is progressing.

How amazing are humans?!

According to a recent Facebook post by baby first aid and education service Tiny Hearts Education, this purple (or silver, red, pink or brown depending on skin colour and tone) line appears during labour on the butt of around 75 per cent of mums.

Image: Supplied/Tiny Hearts Education.

While vaginal assessments during labour are the gold standard for finding out what is happening with baby, the purple line on our backsides can be used as an alternative and less painful or invasive option.

The same post says that according to research, as the line between the butt crack gets bigger, the cervix is dilating and baby’s head is moving down in the pelvis. Once the line has reached the very top of the butt crack, it indicates that mum is fully dilated and ready to push.

British midwife and best-selling author Dr Sara Wickham says that while there has not been much research conducted on the purple line, it can be useful during certain labours.

“In early labour, the line is short, and it gets longer as labour progresses,” Dr Wickham writes in an article on her website.

“Some midwives are good at telling how far along a woman is in her labour by looking at the purple line.

“A couple of other important things to know about this are that it is seen far more easily in women with lighter skin, it is sometimes more red than purple, and it is far easier to observe if the woman is leaning forward or on all fours.  

“Which means that it is not quite so useful when women choose positions other than this and/or if they don’t want to have someone staring at their bottom – which I don’t think is at all unreasonable!”

I discovered that because of the invasive and sometimes painful nature of vaginal assessments, research on the purple line and its effectiveness at showing labour progression was conducted in 2010 by Ashley Shepherd and colleagues for BioMed Central. 

Their research proved that the line did indeed exist on 76 per cent of the women they worked with, and that it was far more likely to appear when a woman was in spontaneous labour as opposed to being induced.

Side note: Listen to Leigh Campbell's birth story. Post continues below.

The conclusion made by Ashley and her research team, however, was that while the purple line was a useful guide for midwives and doctors, more research needed to be done before it can completely replace vaginal assessment in labour.

For us women, it seems there are no easy wins when it comes to childbirth. But the more we know, including about this remarkable purple line on many of our butts, the better informed our decisions can be around our future birthing options.

And as the Tiny Hearts Education team point out - birthing is more a marathon than a sprint, and purple line or not, our bodies work damn hard to bring beautiful babies into the world.

Feature Image: Facebook/@tinyheartseducation