The Red/Purple Line: An Alternate Method For Assessing Cervical Dilation Using Visual Cues

By Mindy Cockeram, LCCE

Today’s blog post is a repost of one of the most popular posts ever shared on our blog. It is written by Mindy Cockeram, LCCE.  Mindy explores the “mystical” red/purple line that has been observed to provide information about cervical dilation without the need for a vaginal exam. Have you seen such a line.  Do you have other ways of identifying dilation that do not involve cervical exams?  Please share in the comments- Sharon Muza, Science & Sensibility Community Manager.

When couples in my classes are learning techniques for coping in labor, such as the Sacral Rub (sacrum counterpressure), Double Hip Squeeze and Bladder32 accupressure points,  I always talk about the great position the partner is in for spotting the red, purple or dark line (depending on skin color) that creeps up between the laboring woman’s buttocks and how – by ‘reading’ that line – he or she may be able to assess more accurately the woman’s cervical progress than the health care providers!  This empowering thought is often met with smiles and laughter especially when I translate ‘natal cleft’ into more recognizable words like ‘butt cleavage’.  Strangely, I’ve never had anyone in class mention having heard of this ‘thermometer’ for accessing cervical dilation by sight and I find this interesting considering the number of medical professionals that come through my classes.

Photo CC http://www.flickr.com/photos/alexyra/214829536/

I first came across this body of research as an Antenatal Student Teacher with the National Childbirth Trust in London.  The article I was reading was in Practising Midwife and was a ‘look back’ at the original article (Hobbs, 1998) published in the same magazine.  The original Practising Midwife article was based on a letter referencing a small study by Byrne DL & Edmonds DK published in The Lancet in 1990.

In the 1990 letter to The Lancet, Byrne and Edmonds outlined and graphed 102 observations from eighteen midwifes on 48 laboring women. It states “The red line was seen on 91 (89%) occasions, and was completely absent in five (10.4%) women and initially absent in three (6.25%).”  The report then goes on to talk about the “significant correlation between the station of the fetal head and the red line length.”  Later the authors write: “To our knowledge, this is the first report of this red line.  We believe that it represents a clinical sign which is easy to recognize and which may offer valuable information in obstetric management.”

So how does this line work?  And why does this it appear?  Practising Midwife Magazine presented a graphic which I have attempted to recreate here.  Basically as the baby descends, a red/purplish (or perhaps brown depending on skin color) line creeps up from the anus to the top of the natal cleft in between the bottom cheeks.  When the line reaches the top of the natal cleft, 2nd stage is probably a matter of minutes away.  A line sitting an inch below the natal cleft is probably in transition.  A line just above the anus probably signifies early labor.

Byrne DL & Edmonds DK, the authors of the original study, surmise that the cause of the line is “vasocongestion at the base of the sacrum.” Furthermore, the authors reason that “this congestion possibly occurs because of increasing intrapelvic pressure as the fetal head descends, which would account for the correlation between station of the fetal head and red line length.”  Fascinating and logical!

Interestingly, I came across a 2nd Scottish study from 2010 published by BMC Pregnancy & Childbirth: (Shepherd A, Cheyne H, Kennedy S, McIntosh C, Styles M & Niven C) which aimed to assess the  percentage of women in which a line appeared (76%. ) The study cited only 48-56% accuracy of vaginal examinations to determine cervix diameter and fetal station.  So why aren’t clinicians using this less invasive visual measure – especially considering how much some women may dread vaginal exams in labor??  Wouldn’t the thought of using a methodology to lower infection rate after rupture of membranes has occurred enthuse Health Care Providers instead of using higher risk techniques?  Or how about using the accuracy of the line at the natal cleft to know when a women using epidural should really be coached to push?

My educated guess is that this information has not yet reached Medical Textbooks and non-standard practices can take years to become mainstream (for example. delayed cord clamping) – and then only if or when women request them or media sensation activates them.  In addition, since laboring women are only intermittently attended by Labor & Delivery staff during early and active labor and often encouraged to “stay in bed,” Health Care Providers aren’t necessarily faced with a woman’s buttocks in labor.  Also vaginal examinations are considered “accurate” so staff have no need to peek between a woman’s natal cleft.   However both these studies, paired with the roughly 50% accuracy rate of manual vaginal exams, show that there is potentially a more accurate and less invasive way ahead.

In The Practising Midwife (Jan 2007, Vol 10 no 1, pg 27), Lesley Hobbs writes “Accurate reading would seem to the key to this practice.  I sometimes notice in myself a wish to see the line progressing more quickly than it actually does; when I do this – and check with a vaginal exam – only to find the line is right, I get annoyed with myself and wish I’d trusted my observations.”  Later she goes on to say “I can now envisage a time when I shall feel confident enough to use this as my formal measurement mechanism and abandon intrusive and superfluous vaginal exams.”

Licensed Midwife Karen Baker from Yucaipa, CA commented “The purple line is a curious thing.  It’s definitely not present on everybody but is more prominent on some than others – especially right before pushing.  It tells us when she’s in full swing if we are in a good position to spot it!”

I often urge couples to send me a picture of the so called ‘purple line’ which I promise I will use only for educational purposes but so far a picture is as elusive as the Loch Ness Monster.  So, as I say in class, ‘show me your purple line’!

Are you a midwife, doctor, nurse or doula who has observed this in a client or patient? Partners, have you seen this when your partner was in labor? Has anyone heard of it or witnessed it?  If you are a childbirth educator, do you feel this is something that you might mention in your classes?  Do you think that the families in your classes might be likely to ask for this type of assessment if they knew about it? Please comment and share your experiences.


Byrne DL, Edmonds DK. 1990, Clinical method for evaluating progress in first stage labour.Lancet. 1990 Jan 13;335(8681):122.

Downe S, Gyte GML, Dahlen HG, Singata M. Routine vaginal examinations for assessing progress of labour to improve outcomes for women and babies at term (Protocol). Cochrane Database of Systematic Reviews 2012, Issue 9. Art. No.: CD010088. DOI: 10.1002/14651858.CD010088.

Hobbs 1998. Assessing cervical dilatation without Vaginal Exams. Watching the purple line. The Practising Midwife 1(11):34-5.

About Mindy Cockeram

Mindy Cockeram is a Lamaze Certified Childbirth Educator teaching for a large network of hospitals in Southern California.  She has a BA in Communications from Villanova University and qualified as an Antenatal Teacher through the United Kingdom’s National Childbirth Trust (NCT) in 2006.  A native of the Philadelphia area, she spent 20 years in London before relocating to Redlands, CA in 2010.





Childbirth Education, Guest Posts, Midwifery, New Research , , , , ,

  1. avatar
    Shannon Wade
    | #1

    Wow! I will certainly bring this to the attention of my clients and see if I can start my own research!

  2. avatar
    Sara Glatz
    | #2

    This was incredibly helpful. As a certified Birth Doula I encounter many women who complain that they hated the vaginal exams during labor and wished there was another way to tell how far along their labor was without the invasive procedure. The red/purple line might be the solution to this. Many of the women I support through labor are already in the hands and knees position when they are nearing the end of transition. It would be an easy position to check the line and also means the mother does not have to move for the typical vaginal exam done at that point. I do hope word of the red/purple line gains publicity and popularity. I teach Childbirth Education and intend on mentioning it in my classes. If enough women start asking about it when they are in labor, maybe we will start a new trend in our hospital.

  3. | #3

    I am a Lamaze certified child birth educator
    I teach this in my class and send them to this website for more information
    I as a Doula have used this and it is amazing how well it works
    not all moms have it but those who do it has been Spot on!

  4. avatar
    Breanna Jewell
    | #4

    Im a nurse, and though I did not learn about the purple line in my education, I did hear about it while researching natural childbirth during my pregnancy. In labor with my second baby, I was preparing to get in the shower after crazy inconsistent labor, and when I glanced in the mirror I saw the line!!! I ran out of the bathroom and showed my husband, and my friend came over and I showed her too. It was awesome! I could feel baby low in my pelvis, like a baseball between my legs, so I knew she was coming soon. Unfortunately I didn’t get a picture. But it was definently there!!!

  5. avatar
    Elen Capucine
    | #5

    Thank you so much for this great informations! I am a midwife student actually writing an essay about the use of vaginal examination during labour and it’s alternatives so your article really helps. As a way to improve my research I am wondering if you could send me the article you’re citing: Hobbs 1998. Assessing cervical dilatation without Vaginal Exams. Watching the purple line. The Practising Midwife 1(11):34-5, I have been looking everywhere for it and did not find it. Thanks in advence. Elen Capucine

  6. avatar
    Uriah Suskey
    | #6

    Hello, my name is Uriah. I am 34 weeks pregnant. I have the purple line and called a nurse. She’s unaware of the study. I live an hour away from my chosen OB. I’ve heard of it for a while now. I’ll keep doing research. I’ve had 2 kids and I’ve never dilated on my own before. Seeing that line leaves me with excitement! Maybe this will be a normal labor. I hope its accurate! Since I was 30 weeks I’ve began to have Braxton hicks contractions. They are small but noticeable because I lose my breath. I also feel how low my son is and there are times when I just want to drop. Also he pushes down so hard I feel like he’s going to tear me. Anyways, when I spoke to one of my nurses, I had just got out of a warm/hot bath and she said that may be why the line is there. Who knows! I guess I’ll find out in two weeks.

  7. avatar
    Uriah Suskey
    | #7

    Maybe mine is the wrong shade of purple. If I had a way, I’d send you a picture and I’d love to hear what you have to say!

  8. avatar
    | #8

    I am in labour, about 5.5cm dilated. Asked my husband to check my reddish line and it is just over half way up between my anus and the end of my “crack”. Before telling my husband how dilated I am, he said “if true, you must be about 6cms dilated”!!

  9. | #9

    I had a home birth client 3.5 hrs away from me. We used the purple line to detect progress. It was accurate in determining that she WAS progressing, but the lines did not match up to the progress exactly (i.e. she showed 8cm dilation when I arrived she was 6 cm)

  10. avatar
    | #10

    So the line I have my husband says reaches the top of my bottem but I am only 35 weeks I feel lots of pressure down there so what do recommend I do at this point

  11. avatar
    | #11

    Do you still need a picture? Because I have an INCREDIBLE one from my water birth. Shoot me an email if you’re interested. Happy to share!

  12. avatar
    Heidi K.
    | #12

    As a doula I have seen this many times and it’s been accurate every time. I mentioned it to a nurse onc and she looked at me like I was crazy, lol.

  13. avatar
    | #13

    Yes! And I have a photo! I am a photographer and captured the red line during a water-homebirth!

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