Early labor contractions pull on the cervix, which looks a bit like the neck of a turtleneck sweater. Contractions shorten or thin the cervix. This process is called effacement and is measured in percentages.
Your cervix starts out three to four centimeters long. When it is 50 percent effaced, it is about two centimeters long. When it is 100 percent effaced, it is "paper-thin."
Effacement can happen over days before labor starts. Or, it can happen over hours as labor progresses. With a first labor, it can take quite a while for the cervix to completely efface.
First stage active labor
Labor may start slowly because the cervix first thins and then dilates.
Dilation is measured in centimeters, one to 10. Dilation to three to four centimeters is considered to be part of early labor. After four centimeters, labor is considered to be active and contractions are more intense.
In early labor, you may only need to use distraction and relaxation techniques. Active labor, however, requires more coping skills.
When contractions become longer, stronger, and closer together, the key to coping is to relax between the contractions. During the contractions do whatever technique helps you deal with them.
The first stage of labor ends when the cervix is fully dilated and your baby's head slips through the cervix.
The last two to three centimeters of dilation are called transition because it is the transition between the first and second stage of labor.
This is the time that contractions are the most intense.
First stage transition
Second stage is the work of pushing your baby through your vagina (birth canal).
It is more difficult than the distance suggests because your baby must turn to fit through your pelvis.
The drawings below show your baby's journey to birth.
Cervix thins and dilates during labor. As your baby moves through your pelvis, her head usually rotates to face your spine.
As your uterus pushes your baby through your pelvis, her head begins to show, or "crown."
After most of your baby's head is born, her shoulders move through your pelvis and she begins to rotate again.
After your baby's head and shoulders are born, the rest of her body slips out.
The third stage is the shortest and easiest. It is the birth of the placenta.
Each phase feels different. Contractions are mild to strong. You may feel comfortable between contractions. You may feel nervous, nauseated, or excited.
Try to relax and work with the rhythm of your body.
Allina Health's Patient Education Department, Beginnings: Pregnancy, Birth and Beyond, sixth edition, preg-ahc-90026, ISBN 1-931876-25-8
Allina Health's Patient Education Department experts
If you have had a previous labor, your cervix will start opening or dilating while it is effacing. This is why a second labor is often shorter than the first labor.