The cephalic position
In the last weeks of pregnancy, the fetus assumes the position that will later be the one in which it will cross the birth canal.
The so-called cephalic position, i.e. the one in which the baby’s head is positioned low and will therefore be the first to appear, is considered the best and safest for a traditional birth.
This for a very simple reason: the part of the baby’s body with the largest diameter is its head, and if the mother’s cervix is sufficiently dilated and allows it to pass without excessive difficulty, the rest of the body will also follow suit. a certain naturalness.
Somersaults and soccer
It usually happens in the last weeks of gestation that the fetus begins its “maneuvers” to prepare for the position in which it will be born.
There are those who are lucky enough to notice with some clarity the “somersault” of the child who turns upside down, but more often we rely on small signals. For example, kicks can indicate, if facing the top of the belly, that the feet are there and, therefore, the head is already facing downwards. Even easier to feel the shape of the feet from the outside when the fetus keeps them “pointed” for a while.
Hiccups and pressures
Another potential indicator that the baby has settled in the head position is his hiccups: if you feel it in the lower part of the belly, it is possible that the little head is there. Possible, however, certainly not: we are talking about signals to be interpreted, not incontrovertible evidence. In the same way, a certain pressure under the ribs can be connected to the cephalic position, when the baby’s pelvis, or rather his buttocks, is pressing against the upper part.
Vertex cephalic position
The ideal position for childbirth is called “Vertex cephalic position”. In this case, the baby is positioned in the easiest way for delivery, i.e., in addition to having its head downwards, it also has optimal neck flexion, while the back of the head comes out first. In addition to being the best, this position is by far the most frequent, and the one that allows for the fastest ejection.
Front presentation
Although it is, as we have seen, the best and most common position, even the cephalic position can hide its small pitfalls. If, for example, instead of the back of the head, the forehead is the first to appear (front presentation), descent along the birth canal may not be possible because the diameter is too large even for the dilated uterus.
This is a rather rare or transitory position. However, if the fetus does not bend the neck further allowing the head to position itself vertex, a cesarean delivery should be performed.
Presentation of bregma and face
Similar problems are encountered if the top of the head, where the fontanelle is located, is the first to appear: this, called bregma presentation, always derives from an incomplete flexion of the neck and can cause a dilation of the times of labor.
Even rarer is the frontal presentation, in which it is the baby’s forehead that appears first, with the head turned backwards.
Through vaginal exploration we try to understand in which direction the chin is oriented and, depending on the precise position, we can understand if it is necessary.
Katherine Johnson, M.D., is a board-certified obstetrician-gynecologist with clinical expertise in general obstetrics and gynecology, family planning, women’s health, and gynecology.
She is affiliated with the Obstetrics and Gynecology division at an undisclosed healthcare institution and the online platform, Maternicity.com.