As you near your due date, you might be wondering when labor will start. The textbook series of events usually involves:

  • your cervix getting softer, thinner, and opening
  • contractions starting and growing stronger and closer together
  • your water breaking

Your doctor may start checking how you’re progressing at each prenatal checkup during your last trimester. When might you go into labor if your doctor tells you you’re already 1-centimeter dilated? Here’s what to expect.

What does dilation mean?

Your cervix is the passageway from the uterus to the vagina. During pregnancy, hormones in your body cause many changes. One change is that the mucus gets thicker in the opening of the cervix, causing a plug. This prevents bacteria and other pathogens from reaching the developing baby. Your cervix typically remains long and closed (around 3 to 4 centimeters in length) until you get closer to delivery day.

During the first stage of labor, your cervix will start to open (dilate) and thin out (efface) to allow your baby to move through your birth canal. Dilation starts at 1 centimeter (less than 1/2 inch) and goes all the way to 10 centimeters before there’s enough space to push your baby into the world.

Dilation and labor

You may have no signs or symptoms that your cervix has started to dilate or efface. Sometimes, the only way you’ll know is if your doctor examines your cervix at a routine appointment late in your pregnancy, or if you have an ultrasound.

The cervix of first-time moms may remain long and closed until delivery day. Moms who’ve had a baby before may be dilated for weeks leading up to their delivery day.

Contractions help the cervix dilate and efface from the beginning stages to the full 10 centimeters. Still, you may be dilated slightly without noticeable contractions.

Other signs of labor

Being 1-centimeter dilated doesn’t necessarily mean you’ll go into labor today, tomorrow, or even a week from now — even if you’re close to your due date. Fortunately, there are other signs you can look out for that might indicate your baby is on their way into the world.

Lightening

You may have heard that your baby will drop close to your due date. This process is called lightening. It describes when your baby starts to settle lower in your pelvis to prepare for delivery. Lightening may happen in the weeks, days, or hours before you go into labor.

Mucous plug

Your cervix protects your baby during pregnancy, and this includes your mucous plug. As your cervix begins to dilate, bits and pieces of the plug may start to fall out. You may notice mucus on your underwear when you use the restroom. The color can range from clear, to pink, to blood-tinged. Labor may happen the day you see your mucous plug, or several days later.

Contractions

If you feel your belly tighten and release, you may be experiencing practice contractions (Braxton-Hicks), or the real deal. The key is to time whatever tightening you’re feeling. Time if they’re coming randomly, or in regular intervals (every 5, 10, or 12 minutes, for example). Usually, if these contractions are infrequent and painless, they’re practice contractions.

Read more about Braxton-Hicks vs. real contractions.

If they grow stronger, longer, and closer together and are accompanied by cramping, it’s a good idea to let your doctor know what’s going on.

You may also feel contractions start in your back and wrap around your abdomen.

Rupture of membranes

One of the more classic labor signs is your water breaking. If this happens, you may experience a large gush, or a trickle of fluid. The liquid is typically clear and odorless. It’s important to call your doctor if you suspect your waters have broken. Take note of how much fluid you experienced and any secondary symptoms (contractions, pain, bleeding) you have.

When to call your doctor

Preterm labor (before 37 weeks)

If you’re experiencing bleeding or leaking of fluid at any point in your pregnancy, call your doctor or midwife right away.

Also call your doctor if you’re having frequent contractions, pelvic pressure, or other signs of labor weeks (or months) ahead of your due date.

Term labor (37 weeks or more)

Let your doctor know about any symptoms of labor you’re experiencing. Contact your doctor if you think you may have dilated early (for example, if you lose your mucous plug or have bloody discharge).

Call your doctor right away if you experience contractions that are closer than three to four minutes apart, lasting 45 to 60 seconds each.

The takeaway

Being 1-centimeter dilated means that your body may be on its way to preparing for your little one’s arrival. Unfortunately, it’s not a reliable indicator of when the whole process will truly kick into high gear. Try to remain patient, keep in close contact with your doctor, and monitor yourself for any other labor symptoms. Call your doctor if you notice changes they haven’t discussed with you before.