How Dilated Am I? by Gina Potts
3 June 2017
I had a great hypnobirthing session today with a really lovely couple who will soon become parents for the first time. We discussed the question of how one knows how dilated a woman is during labour? And whether an internal vaginal exam (VE) is the only way of knowing?
There are several external signs that indicate how advanced a woman's labour is. Most experienced midwives should be able to observe these, so VEs are not always essential. These external signs are summarised with references below:
The Purple Line
(Hobbs L (2007) 'Assessing Cervical Dilatation without VEs: watching the purple line revisited' IN The Practising Midwife 10 (1) 26 : 27)
A bluey/purpley line [or silvery on women with darker skin] creeps up between the woman's buttocks as labour progresses from the anus upwards. When it reachs the top of the buttocks the woman is normally fully dilated. This happens in 89% of women and is best observed when a woman is on all fours or kneeling.
The Rhombus of Michaelis
(Sutton J (2003) 'Birth without active pushing and a physiological second stage of labour' IN Wickham S ed Midwifery Best Practice Edinburgh: Books for Midwives)
The lowest three lumbar vertebrae and the sacrum move backwards and the ilia fan outwards increasing the pelvic capacity. Only happens in second stage if the woman is upright or on all fours. If naked you can see it, if clothed then you can feel a 'lump' (diamond shaped) on her lower back - around the area a lot of women with OP babies want pressure adminstered. [This provides a little bit of extra space for baby coming out, but not if the woman is on her back]
The Smell of Birth
(Wickham S, Roberts K, Howard J & Waters S (2004) 'body wisdom ~ smelling birth' IN The Practising Midwife 7 (1) 30 : 31)
As the woman enters transition smell in the room changes however not many people can smell it. To some it smells of sex, normally tend to notice it outside of hospitals though, maybe there are too many other smells in hospitals.
Angle of the Body During a Contraction
(Lemay G (2005) 'To push or not?' IN Midwifery Today 74 p7)
As a woman progresses in labour she'll align her upper body with her pelvis and as her labour progresses if she is standing then she'll lean further forward than before (so by tranisition she'll be nearly bent in two at the waist.
Vocalising of the Birthing Mother
Many people who attend births observe that the sounds the woman makes change as labour advances. This does not necessarily equate to screaming or yelling. A birthing woman naturally experiences a turning inward into herself, and her primal instincts can kick in. So women and the birth attendants report animal-like sounds, moaning, mooing, groaning, humming and other sounds. As labour advances, birth attendants can look out for changes in how the birthing mother sounds as another sign of baby's arrival coming closer.
You can read more here, along with discussion amongst midwives about their observations of the above occuring. For me, the above is further remarkable proof of how amazing and perfectly designed a woman's body is to birth a baby, without unnecessary interference and intervention.
My hope is that as women learn more about how amazing and powerful their bodies are, they will be filled with the confidence to give birth without fear or anxiety. And to approach birth with joyful anticipation, not just of meeting one's baby, but also of being able to fully experience this most empowering and beautiful experience.
Wishing you a calm, gentle birth.
Gina Potts is Director of ZenBirth UK. She comes from an academic research background, focusing on women's history, writing and feminism. Since 2009 has spent much of her time researching into all aspects of maternity care, pregnancy, birth and women’s postnatal health. In 2011, she founded ZenBirth and has helped hundreds of couples have a positive birth experience.