Unraveling the Mystery of Non-Engagement

Did either baby have any molding on the head? Molding would typically only be seen after many hours of very strong and frequent uterine contractions. Actually, many babies that haven’t engaged even with strong, frequent contractions show no molding of the head. But its a clue that may help if it is present.

Sometimes if a woman’s outlet is quite wide, the inlet is narrowed, by a torque that closes the brim and opens the outlet. Think of a clothes pin and as you open the clothes pin the top of the sticks get closer together. This can be corrected if it is the case. A spasm in the ligaments is the cause. The right kind of body work is necessary.

How would you know if you have a wide outlet?

The lines represent (from the top) the pelvic inlet, the midpelvis, and the outlet diameters.

A posterior baby remains on the pubic bone and not engaged.

Pelvimetry means measuring the pelvis. We can do a simple approach to get a general idea of pelvic shape. The following is a just for fun self test. The test is not detailed enough to be definitive. See an experienced midwife, obstetrician, or labor and delivery nurse for verification of your pelvic size and shape. MRI measurements may help, but really, labor decides if the pelvis is big enough.
Let’s talk about three places in the pelvis for a self-check.

I include this because many women ask, not because I think that the answers tell whether or not you can have a baby through your pelvis. This is a guide, a beginning. The land is not the journey, however. Let’s start the self test.

Lie down, wearing thin stretch pants or undies to do these first two checks. Stand for the last check.
1. )  The Sitz bones, or Ischial Tuberosities, make up the side limits of the outlet.

If the outlet is pulled wide by ligaments and chronic muscle tension (you don’t have to feel tense emotionally for this to have happened over the years), it may be that the inlet is pulled narrow.

To find out see if your own fist fits easily between your sitz bones (externally!).

Image from https://library.jefferson.edu/Collections/DVDs/obgyn101/Text/Abnormal%20L&D/fetopelvic_disproportion.htm
You can lay on your side and use your own fist from behind you. Or, ask your mate.

Closing your hand, place your fist between the tuberosities and choose the best description:

A. You can feel both sitz bones at once on the edges of your fist, or a slight tilt brings you in touch with the second sitz bone.

B. You can easily feel space around your fist in addition before your sitz bones are touched by your fist. Roomy.

Now,

2.)  Feel for your pubic arch.

Pubic arch in red

Laying on your back with knees bent, wrap your fingers around your pubic arch. It’s like a kid grabbing themselves to avoid peeing their pants. You don’t have to smash your fingers into your urethra, be kind. The measuring place is between the top and the sitz bones at the bottom of the pubic arch.

A. Is there room for three fingers or 1 and a bit more?
B. Or is the arch very wide, even four of your own fingers fit across?

This second check verifies the first check.

Now stand,

3. )  Approximate the depth of your inlet.

Have a helper measure the visual distance between your pubic bone and top of your sacrum.

They kneel next to you and by just eyeing the distance, not wrapping the measuring tape,

they hold one end to the front and one end horizontally to the back. This is very simplistic.

A. My distance is about 9 inches

B. My distance is about 7 inches

This is a rather subjective measurement. If you have a girlfriend about your size, you can measure each other and compare.

By far, most people measure 9 inches or a little more. Remember, you aren’t measuring fat or clothes,  find the bones and approximate. A measurement of about 7 inches, more or less, might mean the front to back distance is a short distance. See more in pelvic shape.
An alternate way of assessing if one has a Platypelloid Pelvis
4.)  Approximate distance between hips
Stand and measure the distance from hip to hip (ASIS). Use a tape measure or ruler.

Image from https://www.activeortho.com/store/how_to_measure_si_belt.html
I also like the Serola Sacroiliac belt https://www.serola.net/serola-sacroiliac-belt

Your hip to hip bone measurement is
A. 11-13 inches
B. 15-17 inches between boney hips.
The fourth measurement verifies the 3rd.
Outcomes of Your Pelvimetry

In that case, you find close tuberosities (Sitz bones) and a very narrow pubic arch of only 1.5 or maybe 2 fingers across.
Not engaging from a posterior position is common for this pelvic shape. Helping baby be in an ideal LOA position usually brings about engagement and labor progress. It is not uncommon for birth providers not to know how to help engage baby in an android pelvis. Walking the halls is unlikely to engage or rotate a posterior baby in this pelvis.

Another possibility to lack of engagement is a narrow front-to-back pelvic diameter, called the Platypelloid pelvis, which can make engagement an agony when baby starts posterior. Helping this baby into a Left Occiput Transverse position is the only way for baby to engage. That will immediately relieve the brim pain and labor will likely stop so the uterus can rest and then after a meal, labor will resume and bring the baby in 6-8 hours. If the uterus doesn’t need a rest (maybe because baby started LOT then labor may be 24 hours or less in this pelvis, a second baby may come in 6-8 hours total if starting LOT.)
When pelvic shape is the issue, we see that skills in supporting a labor with a pelvis that is not round is of key importance. Skills to support labor are slipping away from the world. Spinning Babies is determined to bring them back!