During labor, the cervix changes from a tightly closed entrance to a fully open exit for the baby.
Looking at a cervix dilation chart can help people to understand what's happening at each stage of labor.
Each woman experience labor differently. In this article, we discuss in detail how the cervix is likely to change throughout the stages of labor, and what to expect at each stage.
Most of the time, the cervix is a small, tightly closed hole. It prevents anything from getting into or out of the uterus, which helps to protect the baby.
During labor, intense contractions of the uterus help move the baby down and eventually out of the pelvis, and into the vagina. These contractions put pressure on the cervix and cause it to expand slowly. Contractions tend to get stronger, closer together, and more regular as labor progresses.
Most medical guides divide labor into three stages:
- Stage one: early, active, and transition labor. Contractions begin, the cervix dilates, and the baby moves down in the pelvis. Stage one is complete when the cervix has dilated to 10 centimeters (cm).
- Stage two: The body begins pushing out the baby. During this stage, women often feel a strong urge to push. This stage ends with the birth of the baby.
- Stage three: Contractions push out the placenta. This stage ends with the delivery of the placenta, usually within a few minutes after the birth of the baby.
However, many women in labor may feel that they are experiencing many more stages than this.
Stage one: early labor
In the early stages of labor, the cervix dilates to the following sizes:
- 1 cm, about the size of a cheerio
- 2 cm, the size of a small to medium-sized grape
- 3 cm, the size of a quarter
Late in pregnancy, the cervix may have already dilated several centimeters before a woman experiences any symptoms of labor.
Some women, particularly those who are giving birth for the first time, have difficulty telling whether labor has begun. This is because contractions in early labor are often mild and irregular, growing steadily more intense as the labor progresses and the cervix dilates.
This increase in intensity may take just a few hours or can take many days. Knowing whether this is actual labor can help people to prepare.
During true labor, a person's contractions:
- are not just on one side of the body
- begin at the top of the uterus, and feel like they are pushing down
- get more intense and regular with time
- do not stop with rest or taking a warm shower
Some women may benefit from resting or eating a snack at this stage to ensure they have enough energy for the more tiring stages ahead.
Stage one: active labor
During the active stage of labor, the cervix dilates to the following sizes:
- 4 cm, the size of a small cookie, such as an Oreo
- 5 cm, the size of a mandarin orange
- 6 cm, the size of a small avocado or the top of a soda can
- 7 cm, the size of a tomato
Labor contractions become more intense and regular during active labor. Many women find that the main characteristic of active labor is that the contractions are extremely painful rather than uncomfortable.
At this stage of labor, some women may choose medication, such as an epidural to cope with the pain. Others prefer to manage the pain naturally. Changing positions, moving, and remaining hydrated can help with the pain of active labor.
Stage one: transition phase
During the transition phase of labor, the cervix dilates to the following sizes:
- 8 cm, the size of an apple
- 9 cm, the size of a donut
- 10 cm, the size of a large bagel
For many women, transition is the most challenging stage. However, it is also the shortest. Some people begin feeling an urge to push during the transition stage. It is also common to feel overwhelmed, hopeless, or unable to cope with the pain. Some women vomit.
Some women find that the coping strategies that worked well in the earlier stages of labor are no longer useful. Transition tends to be short and is a sign that the baby will soon arrive. Moving, changing positions, and visualization exercises can help.
The cervix continues dilating during transition, and transition ends when the cervix has fully dilated.
Stage two: full dilation and pushing
Once the cervix has reached 10 cm, it is time to push the baby out. Contractions continue but also produce a strong urge to push. This urge might feel like an intense need to have a bowel movement.
This stage can last anywhere from a few minutes to a few hours. It is often longer for those giving birth for the first time.
Historically, doctors told women to push according to a schedule, to count to 10, and to remain on their backs. Today, the advice is very different, and research says it is safe for women to push according to their body's cues and for as long as feels comfortable.
Pushing from a standing or squatting position may also help speed things along. Allowing people to push from a range of positions gives the medical staff better access to the woman and baby should they need to assist with the delivery for any reason.
As a woman delivers the baby, she may feel an intense burning and stretching as her vagina and perineum stretch to accommodate the baby. This sensation typically lasts just a few minutes, though some women tear during this process.
Stage three: after the birth
A few minutes after the birth, a woman may experience weaker contractions. After a contraction or two, the body should expel the placenta.
If the body does not entirely expel the placenta, a doctor or midwife may have to help deliver it. Sometimes, they will give a woman an injection of synthetic oxytocin to speed up delivery and prevent excessive bleeding.
Shortly after delivery, the cervix begins contracting back down to its previous size. This process can take several days to several weeks.
As the uterus and cervix shrink, many women will feel some contractions. Most women bleed for several weeks after giving birth.
Labor is different for each woman. It typically lasts longer with a first birth, but the length and type of labor vary greatly between individuals.
Some people experience labor that consists of a weaker type of contraction for days or weeks before giving birth. Others give birth in a matter of minutes, while some labors take days. Most fall somewhere in the middle.
Labor often starts slowly, becoming progressively more intense. It may also start and stop, or slow during moments of stress or intrusion.
Visualizing the cervix expanding might help some people understand the source of labor pain, offering a sense of control and deeper insight into the processes of labor.