What Is the Meaning of the Numbers During Labor Dilation?

As the end of pregnancy approaches, the process of cervical dilation begins.

As birth approaches, a pregnant woman may be told she is beginning to dilate. Dilation numbers are given in centimeters, measuring the degree of cervix opening.

The Cervix

The cervix is the part of the uterus surrounding the opening at the base. Also called the "neck" of the uterus, the baby will pass through it during vaginal delivery.

Before Delivery

Before labor begins, the cervix is described as long and hard. Its opening is completely closed.

Dilation

The cervix must open before birth; this process occurs during labor and is called dilation. Dilation is measured in centimeters; 10 cm (about 4 inches) is considered fully dilated and ready for birth.

Effacement

A related change, the shortening and softening of the cervix, is called effacement. It is measured in percentages according to how the cervix feels to the health practitioner.

Stages of Labor

Dilation and effacement may begin several weeks before birth. Early dilation is no more than 1 to 2 cm; the contractions of active labor open it the rest of the way within a few hours.

References

• American Pregnancy Association: Signs of Labor
• Mayo Clinic: Signs of Labor