The Pelvic Floor’s Role During Labor

When we think about birth, we often picture contractions, pushing, and eventually meeting the baby. But there’s a key player in this process that doesn’t get nearly enough attention: the pelvic floor.

As a pelvic floor and sports physical therapist, I spend a lot of time helping people understand how this group of muscles works for daily life, pregnancy, labor, and postpartum recovery. Let’s walk through the basics of pelvic floor anatomy and what actually happens during labor.

External Anatomy: What You See

When people say “vagina,” they’re often referring to the whole outside area, but technically that’s the vulva. The vulva includes the clitoris in the front, the inner and outer labia, the urethra, and the vaginal opening. The perineum is the space between the vaginal opening and the anus.

In total, there are three separate openings:

• The urethra, where urine comes out

• The vaginal opening, where a baby is born

• The anus, where stool passes

Internal Anatomy: The Muscles You Don’t See

Inside, the pelvic floor is made up of two layers of muscles that span the entire bottom of the pelvis. These muscles support your internal organs like the bladder, rectum, and uterus. They also control the opening and closing of the urethra, vagina, and anus.

On a daily basis, the pelvic floor helps you hold in urine or stool until you’re ready to go, and then it relaxes so you can empty your bladder or bowels.

There are two regions of the pelvic floor:

• The urogenital triangle in the front, around the vulva

• The anal triangle in the back, around the anus

Both work together to give support, control, and stability.

What Happens During Labor

Here’s the important part: the pelvic floor does not push the baby out. That job belongs to the uterus.

The uterus is made of smooth muscle, which contracts automatically (you can’t consciously control it). During labor, the cervix dilates (opens) and thins out, and the uterus contracts to push the baby down and out.

The pelvic floor’s job is to relax and lengthen so the vaginal opening can expand and allow the baby to be born.

The A-Frame House Analogy

One way I explain pelvic floor function is by picturing an A-frame house.

• Neutral (First Floor): Your pelvic floor is working in its normal supportive role, holding up organs and maintaining control.

• Contraction (Attic): When you need extra support—like if you cough, laugh, or lift something heavy—the pelvic floor contracts. It closes off the openings and lifts upward, like going up into the attic.

• Relaxation (Basement): To go to the bathroom or give birth, the pelvic floor has to relax open and move downward, like going down into the basement.

During labor, the uterus provides the pushing force, while the pelvic floor goes into the “basement” so the baby can pass through.

Takeaway

The pelvic floor is a dynamic system that contracts and relaxes depending on what your body needs. During labor, its most important role is relaxing so the uterus can do its job and push your baby out.

Understanding this balance between contraction and relaxation helps prepare you for birth and sets the stage for recovery afterward.