Why Do Babies Prefer LOA?
It is generally accepted that, given a chance,” ready- to- be- born” babies will choose the “head down, back to the left” position for birth.
What’s so special about this position?
1; There is more space in mother’s abdomen for the large back.
2; It is simple to curl up until the smallest diameter of their head is the leading part. The skull bones are able to slide under one an other at the sutures, making the head even smaller.
3; It is easy to slide under the pelvic sacral prominence into mother’s pelvis.
4; When labour starts the contraction pressure moves down baby’s spine, to end smoothly on the maternal cervix.
5; If mother is upright and mobile, the uterus can tilt forward with each contraction, applying maximum energy to opening the cervix. (No waste lifting baby, uterus, and liquor as when mother is reclining).
6; Once second stage occurs, baby has only to lift his/her head to emerge.( No need for deliberate maternal pushing.)
7; The whole process is straightforward, as baby is able to make use of all the available space in the maternal pelvis, and the uterus can use all the contraction pressure.
The ROA position works almost as well, but the modified banana / pear shape of the primigravida’s uterus means that it is an option only for second or later babies, but few of them choose it
What Are The Difficulties With ROP
Today many babies are failing to settle into the LOA position for birth. This means that the journey will be harder and slower for both baby and mother.
Why won’t just any “head down” position work.
1; A baby in the ROP position is facing forward in the military, or upright position.
2; He has the longest diameter of his head presenting.
3; As he is above the lower segment of the uterus, he fails to stimulate the maternal cervix to soften and shorten.
4; He is very likely to become post mature, or overdue.
5; Until his bottom and the uterus comes forward during labour, he will be unable to get his head under the maternal sacral prominence.
6; As his head is still to upright, he must try to come straight through the middle of the maternal pelvis
7; His skull bones don’t fold, but the parietal bones must change their shape to allow his head to fit. ( the sugar loaf head )
8; Pressure from contractions is on the lower uterine segment instead of the cervix, so dilatation may stop at about 5cms.
9; If he succeeds in getting through the cervix, he may rotate to bring his back forward, and descend more easily.
10; If he fails to rotate far enough he may become a “transverse arrest”
11;He will need maternal effort to be born.
There are other difficulties for a baby in the OP position, but this will be enough to think about.
The “passage the powers and the passenger” function very well when, and only when, the baby is able to make use of all the available pelvic space, and his mother is free to respond to his signals.