Cervical dilation is how open your cervix is, measured in centimetres from 0 (closed) to 10 (fully open, ready for pushing). A single number — "you're 3 cm" — tells you where you are on that scale, but not how fast you'll get to 10, because every labour moves at its own pace.
What each number generally means
- 1 cm. Early cervical changes may be starting. This can happen days before labour actually begins, especially in a first pregnancy.
- 3 cm. Early labour for many women. Contractions may still be irregular and manageable.
- 5 cm. Active labour usually starts around here. Contractions tend to get stronger, longer, and closer together.
- 7 cm. Labour is progressing well. This stage can move faster than the earlier centimetres.
- 10 cm. Full dilation. Your cervix is completely open and your body is ready for the pushing stage.
Why the number alone doesn't tell the whole story
Dilation is only one piece of what your doctor or midwife is tracking during labour. They're also watching:
- Cervical effacement — how thin the cervix has become, not just how open
- The baby's station — how far down the baby has moved into the pelvis
- Contraction pattern — frequency, duration, and strength
- Cervical position and consistency — whether it's soft and forward-facing or still firm
- The baby's heart rate and your overall progress
Two women can both be "5 cm dilated" and be in very different places in labour, depending on these other factors. That's why your doctor looks at the whole picture, not the centimetre count in isolation.
Some women go from 3 cm to 10 cm in a few hours. Others take much longer. Both can be completely normal — don't compare your labour to someone else's.
Why progress isn't linear
Dilation often speeds up as labour goes on. The early centimetres (0 to 3-4 cm) can take the longest, especially in a first pregnancy, while the stretch from active labour to full dilation can move noticeably faster once your body is in rhythm. This is a general pattern, not a guarantee — some labours progress steadily throughout, and some stall and restart.
What actually tells you labour is close
Rather than fixating on a single dilation number, your doctor is watching for:
- Contractions that are regular, strong, and getting closer together
- Steady change in dilation and effacement on repeat checks, not just one reading
- The baby's station moving down
- How you're coping and how the baby's heart rate looks through contractions
If you're checked and told a number, ask what it means for what happens next, rather than trying to calculate a timeline from the centimetres alone.
Frequently asked
If I'm 3 cm dilated, how long until I deliver?
There's no fixed timeline. Some women progress from 3 cm to full dilation in a few hours; others take much longer, especially in a first labour. Your doctor's assessment of your overall progress matters more than the raw number.
Does 1 cm dilation before labour mean it's starting soon?
Not necessarily. Some women walk around 1-2 cm dilated for days or even weeks before labour actually begins, particularly with a first baby. It's a sign of preparation, not a countdown.
Is dilation faster in a second or later pregnancy?
Often, yes — but it varies. See our guide on why the cervix can dilate faster in a second delivery for what tends to change and why.
Can dilation go backwards?
True regression is uncommon, but dilation can appear to stall for a period before progressing again — particularly in early labour. This is one reason your doctor tracks the trend over repeat checks rather than reacting to a single reading.
What's the difference between dilation and effacement?
Dilation is how open the cervix is; effacement is how thin it has become. A cervix can efface significantly before it starts to dilate much, or the two can progress together — your doctor tracks both.