Types of the pelvis and their relationship in childbirth

Muhammad Usman Babar
4 min readJan 6, 2021
Types of the pelvis

The types of pelvis favor or hinder childbirth, but they are not the only factors that influence this. The female body also releases hormones during pregnancy to make the pelvic area more flexible.

The different types of pelvis influence the development of labor. Let’s start by saying that the pelvis is a set of bones that are located in the lower part of the torso. Specifically, between the lower back and the thighs.

The pelvis performs important functions, such as supporting the upper body and connecting it with the lower extremities. Besides, it protects the organs located in that area and allows movements, such as standing or running.

In principle, there are two main types of the pelvis: the male and the female. The usual thing is that the women are wider and open since this facilitates natural childbirth. However, the female pelvis can also have various forms. Let’s see.

What are the 4 types of the pelvis?

The types of female pelvis have been defined based on the three straits that exist within this boneset. The straits are, as the name implies, notches in the bones in that area. The baby has to go through them at the time of delivery.

According to the traditional classification, there are four types of the female pelvis. However, it has been suggested that many women do not fully fit either of these, but instead present combinations of two or more. Despite everything, the conventional classification developed by Caldwell and Moloy in 1930 is still used.

Gynecoid

50% of women have this type of pelvis, which is why it is considered the most common. It is also the bone form that most favors vaginal delivery. It is characterized because it has a rounded or slightly oval shape and has wide straits.

Android

The android pelvis, also known as the infundibuliform, is similar to the male. It is estimated that it is present in 25% of women and is characterized by being narrow and with narrow diameters. Still, this is one of the types that allow vaginal delivery on many occasions.

Anthropoid

The anthropoid pelvis has an oval shape and a narrow diameter at the top. This makes it very difficult for the baby to pass during birth. Therefore, it does not favor vaginal delivery, although it does not eliminate that possibility either. It is estimated that 10% of women have this type of pelvis.

Platipelooids

It is the least frequent modality and is characterized by its very small diameter that does not favor natural birth in any way. Typically, this configuration delays labor and requires a cesarean section.

How can pelvic types influence childbirth?

It is important to note that the female pelvis is not static, but moves. In fact, it is possible to make it more flexible through training. Therefore, pelvic types are a point of reference, but they do not always have to determine the type of delivery to be had.

That said, it should be noted that the narrow pelvis gives rise to areas known as Hodge planes. There are four of them and they are numbered from top to bottom. Thus, the first plane is the highest and the fourth the lowest.

The baby has to go through a strait and occupy each of the planes in succession. It descends and rotates through the birth canal to finally reach the outside world. In principle, all types of pelvis allow natural childbirth, however, each one prints certain variations.

Types of pelvis and childbirth

The types of pelvis determine the characteristics of the narrow and the planes. In this way, they favor or hinder the baby’s passage:

  • Gynecoid: its wide and open shape is the most conducive to vaginal delivery. The baby has a wide space to go from one plane to the other.
  • Android: This type of pelvis makes labor difficult. The usual thing is that the baby has to move very slowly from one plane to the other. May require a cesarean section.
  • Anthropoid: it is more spacious in the front plane than in the back. Allow vaginal delivery, but it may be more time-consuming and difficult.
  • Platypeloid: the baby has great problems passing through the pelvic inlet and this makes delivery very difficult. This is one of the types of the pelvis that usually requires a C-section.

How to identify the type of pelvis?

The types of pelvis do not always fully conform to the classification we have described. Likewise, hormones are released during pregnancy that helps the pelvic ligaments and joints to relax more, to facilitate delivery.

Now, there is information on the internet and other sources that, apparently, allow us to determine what type of pelvis each woman has. However, those data are not very reliable. The best way to establish this is with your doctor or midwife.

A knowledgeable person performs a pelvic exam in which the bones are measured. This examination is known as pelvimetry and it allows us to determine what type of pelvis corresponds to each particular case.

Not only the types of pelvis matter

The types of pelvis are not the only factors that affect the ease or difficulty of childbirth. Other elements influence, such as the position of the baby, the condition of the umbilical cord and the placenta, the presence of several fetuses, and the anatomical state of the mother.

It is important to have a regular check-up with the obstetrician and report any pain, pressure, or discomfort in the pelvic area. Some guided exercises during pregnancy help to make this area even more flexible, thus favoring vaginal delivery.

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