Pelvic Inlet vs Outlet? Let me tell you what you need to know!

As a pelvic floor PT, I love helping women, and their partners, understand their bodies during pregnancy, birth, and postpartum recovery. When it comes to labor and delivery, understanding the anatomy of your pelvis, the process of descent through the birth canal, and tools for pain modulation can help you feel more confident and prepared for birth.

In this post, we’ll explore the pelvic inlet and outlet, define the different stations of labor, and highlight some highly effective comfort measures like pelvic squeezes and other pain modulation techniques that I often teach my patients to help the baby along their journey into the world!

The Pelvis During Birth

The pelvis is not a rigid structure which many people don’t realize. The pelvic bones connected in the front and back and air as a mobile foundation playing a critical role in birth. The bony pelvis is made up of the two innominate bones (ilium, ischium, pubis) joined at the front by the pubic symphysis and at the back by the sacrum and coccyx. The pelvic inlet and outlet are thus definite by these bones.

Pelvic Inlet vs. Pelvic Outlet

When we talk about labor and delivery, we often focus on the pelvis as having two important "gateways": the pelvic inlet and the pelvic outlet.

The Pelvic Inlet

The pelvic inlet is the upper opening of the pelvis, shaped somewhat like an oval or heart depending on your pelvic type. It’s bordered by the sacral base and the pubic symphysis in front. This is the entry point into the pelvis that the baby must navigate first. The inlet tends to be wider side-to-side which is why babies often enter the pelvis looking sideways.

The Pelvic Outlet

The pelvic outlet is the lower opening of the pelvis (think the area between the sit bones and tailbone. The outlet is generally wider front-to-back, which facilitates the final stage of delivery as the baby rotates and extends the head to pass under the pubic bone. You can imagine now why changing positions during birth is imperative to help the sacrum and tailbone move for baby to exit the outlet!

Understanding Fetal Stations in Labor

Stations describes how far the baby’s head has descended into the pelvis and readiness for birth.

Here’s a breakdown:

• -5 station: Baby’s head is floating above the pelvic inlet.

• -3 station: Baby’s head is entering the pelvis (engagement).

• 0 station: Baby’s head is at the level of the ischial spines considered "engaged."

• +3 station: Baby’s head is low in the pelvis, elongating the pelvic floor.

• +5 station: Baby’s head is crowning, ready to be born.

Understanding stations helps you visualize progress and can also guide position changes during labor!

How Hip (Pelvic) Squeezes Help

One of my favorite hands-on techniques for supporting labor comfort is a double hip squeeze, often taught to partners or doulas.

How to:

• The support person places hands on the outside of the birthing person’s hips (over the iliac crests).

• By squeezing inward and slightly upward, pressure is applied that temporarily narrows the pelvic inlet but widens the pelvic outlet.

• This not only provides space for the baby to descend, but also gives the mother a sense of counterpressure that can relieve the deep ache of contractions, especially in the sacrum and lower back.

Other Pain Modulation Techniques

1. Position Changes

Changing positions every 20–30 minutes can improve comfort, facilitate rotation of the baby, and optimize pelvic diameters.

• Forward-leaning over a birth ball

• Squatting or kneeling in early labor

• Side-lying with knee in and foot out to open outlet

2. Breathing and Vocalization

Slow, controlled exhalations or low, open sounds (like mooing or moaning) encourage the pelvic floor to stay soft and responsive rather than tightening in response to pain.

3. Warmth and Water

A warm compress over the perineum, a shower, or laboring in a tub can provide pain relief by calming the nervous system and relaxing muscles.

4. Rebozo Sifting

Using a rebozo around the hips and belly with gentle rocking movements relax tight muscles and can position the baby for smoother descent.

If you’re pregnant and curious about preparing your body for labor, consider working with a pelvic floor physical therapist. Together, we can practice labor positions, practice pushing, educate your partner and even discuss early postpartum topics.

If you are looking for pelvic floor physical therapy in Centennial, Cherry Creek, Wash Park, Platt Park, Cory Merrill, Hilltop, Castle Pines, Castle Rock, Cherry Hills Village, The Highlands, Arvada, Littleton or beyond, you know where to find us! I specialize in pregnancy, labor preparation, and postpartum recovery. Reach out to learn more about how PT can help you have a more comfortable and confident birth.