Updated: Nov 14, 2020
Cervical dilation: a modern obsession
In a technical hospital setting, cervical dilation is often at the center of the staff's preoccupations. While it can give serious information about the progression of labour, it is not the only criterium that predicts the imminence of the baby's crowning.
If you are at all familiar with Spinning Babies®, you know how the position of the baby has a great importance and how focusing on the cervical opening only is counterproductive.
Normal labour progress assessment used to be dictated by Friedman's curve. This "gold standard" is outdated and should no longer be a reference for assessing what is normal or abnormal labour. Too many labours labelled "failure to progress" consequently led to unnecessary C-sections and birth traumas.
Each birthing person labours on a different pattern, each birth follows a different scheme. Labour can pause in a totally healthy and normal way and resume on its own.
Labour often stalls when it is disturbed: induction, epidural, lack of privacy, stress, pressure, restricted movements, incessant vaginal exams.
What do you need to know about vaginal exams?
Vaginal exams have been used to assess the cervical ripening, effacement and dilatation, as well as to check for the baby's station and an eventual cervical lip at the time of "pushing". Some birthing people can feel encouraged to know that they are already reaching 8 cm. It can help them to distribute their remnant efforts. These could be considered as the benefits of such an internal exploration.
What are the risks? Once the water has broken, each vaginal exam carries a risk of infection, even if sterile gloves are used. Indeed, bacteria at the border of the cervix can be accidentally pushed inside. Another risk is discouraging the labouring person. If, after long hours of labour, the midwife announces 5 cm, this can be welcomed with a lot of disappointment. There is also a small risk of a "wrong" assessment. It happens that a first midwife says the cervix is 7cm dilated and a second midwife coming one hour later finds out 6-6,5 cm. How disturbing and confusing for the birthing person! These different assessments are understandable. People have different finger size or position can affect the evaluation.
So the question is: What are the alternatives?
Gentle alternatives to "fingers in the cervix" or non-invasive ways to know your labour is progressing
I found a lot of information while reading The Doula Guide to Birth: Secrets Every Pregnant Woman Should Know by Ananda Lowe and Rachel Zimmerman. I recommend this book written by two dedicated doulas, with all my heart.
1. Change in contraction Contractions are regular, become closer to each other or contractions become more intense. The behaviour and moves of the birthing person can change in function of the intensity or phase of labour. Different sounds, chants or moans can as well indicate the progress of labour.
2. Belly is higher With labour progressing, the fundus goes higher. In the beginning of labour, you can place a full hand between your plexus (bra line) and your fundus (belly top). The more the labour progresses and the less fingers you can fit. At 3 fingers, you are about 5 cm dilated. At one finger you are probably fully dilated.
3. Bloody show What is tenderly named "bloody show" is actually a small tinted (pinkish, red or brownish) vaginal discharge. All birthing folks are different, of course, but some experts tend to notice two types of bloody shows. One bloody show would appear before the onset of labour (one week, 24-hours, or on the D day) when the cervix is about 2 cm dilated, and a second bloody show would appear in the heat of labour when the cervix is about 8cm dilated. These are general notes.
Just a tiny amount of bloody discharge, although the smallest amount might seem scary at first. If it's more than a little, consult immediately.
4. The Purple Line I never meant to cause you any sorrow I never meant to cause you any pain I only wanted one time to see you birthing I only wanted to see you birthing with a purple line Purple Line, Purple Line...
Just like the "linea nigra" growing on the pregnant belly, the "linea purpura" grows habitually between your butt cheeks during labour. The colour varies from red in pale skin tones to purple or even silvery in darker skin tones. Some call it the "bottom line" and the bottom line is that it can indicate your labour progress.
The appearance of the purple line is caused by the vasocongestion in the sacrum resulting from the baby's head putting pressure on the cervix. The first mention of the purple line goes back to 1990 with Byrne and Edmonds who sent a letter to The Lancet. They attributed the first observation of the purple line to Sister H. Lake. Their little study focused on 48 women. 89% of them had a visible "purple" line. Some had no line at all. Fast forward to 1998: This is the turn of Lesley Hobbs, a British independent midwife, to write about the phenomenon. Last update about the mysterious line dates from 2010 when Shepherd et al published the results of their research study. They observed 144 women in labour and noticed the presence of the line in 76% of them. Their findings showed a medium positive correlation between the length of the purple line, the dilation of the woman’s cervix and the station of the baby’s head.
5. Descent of the baby through external palpation Experienced midwives can palpate the abdomen with their hands and identify the baby's station in the pelvis.
6. Descent of the baby through external foetal monitoring When the baby goes down, their heartbeat can be caught lower on the birther's abdomen.
7. Spontaneous Rupture Of Membranes (SROM)
SROM is the spontaneous rupture of membranes. When "the water breaks". This term describes the normal, spontaneous rupture of the membranes at full term (after 37 weeks). The rupture usually causes a gush of fluid. This gush may be quite small or significantly large depending on the amount of fluid in the amniotic sac, and to what extent the foetal head is plugging the hole and retaining fluid in the sac.
The membranes don't always rupture. Sometimes, rarely, the baby is born delicately in its little amniotic cushion, "en-caul".
Not that Niagaresque IRL. Is that the Parliament House?
For twins or other multiples, ultrasounds are used during birth to identify the position of the babies. For singletons, ultrasounds are used with more parsimony.
9. Rectal pressure
With the baby's head descending in the pelvis, a significant pressure will be felt, followed soon enough by an irresistible urge to push and the famous "ring of fire" next door (burning sensation in the vagina when the baby is crowning).
10. Involuntary bowel movement Yes, we talk about "uncontrolled poop". The baby's head is pressing like a thumb on an almost empty toothpaste tube. Such a beautiful omen.
11. Opening of the back The tail bone sticks out. Sometimes the rhombus of Michaelis (a kite-shaped/diamond-shaped area in the lower back) is visible if the birthing person is in an upright position or on all-four. This opening enables extra space for the baby's passage, which is impossible if the birthing person is lying on the back.
12. Seeing the head! (Or the bum or the feet of the baby)