Preterm Labor

Reviewed by James Brann, MD
When you’re having preterm labor, it means you’re having regular contractions beginning before pregnancy week 37. These contractions will result in changes of the cervix including dilation. This is when the cervix opens allowing the fetus to go into the birth canal. Other changes include effacement. This is when your cervix thins out prior to birth.
Preterm birth is when you deliver your child between pregnancy weeks 20-37.

Preterm birth is concerning for doctors because babies born too early may not have fully developed yet. This could lead to some serious health issues including cerebral palsy, which may be a lifelong condition. Other health issues including learning disabilities, which may come about either later in childhood or even as an adult.

Babies born before pregnancy week 34 are most at risk of having health problems, but babies born between weeks 34-37 also have some risk.

Preterm birth risk factors

  • A short cervix
  • Previous preterm births
  • Short time between pregnancies
  • Pregnancy complications including vaginal bleeding and pregnancies with multiples
  • Prior surgeries on the cervix or uterus
  • Smoking cigarettes during pregnancy
  • Substance abuse during pregnancy
  • Low pre-pregnancy weight


Preventing preterm birth

If you’ve already had a preterm birth before and you want to have another child, you’ll want to go in for a preconception care checkup before becoming pregnant. Once you are pregnant, you want to start with prenatal care right away. You may need to see a doctor with experience in high-risk pregnancies. If you have risk factors, you may also need certain medications or treatments for helping to prevent a preterm birth. Treatments are based on risk factors and individual situations.

Symptoms of preterm labor

You’ll want to call your doctor immediately if you have any of these symptoms of preterm labor:
  • Changes in vaginal discharge (bloody, mucus or watery)
  • Vaginal discharge increases
  • Continuous dull, low backache
  • Abdominal pressure that’s low or pelvic
  • Mild case of abdominal cramps, may include diarrhea
  • Your water breaks
  • Frequent or regular contractions, may be painless

Diagnosing preterm labor

Preterm labor is only diagnosed when the cervix starts changing. Your doctor may want a pelvic exam to see if your cervix is changing. You may actually need several exams over a period of several hours to tell. Your doctor will also be monitoring your contractions.

Your doctor may want to do some tests to see if you need to have specialized care or need to go to the hospital immediately. A transvaginal ultrasound exam can measure the length of your cervix. Doctors may also measure the fetal fibronectin, a protein found in vaginal discharge. This protein is linked to preterm birth.

Does preterm labor = preterm birth?

It’s not easy for doctors to know whether women having preterm labor will also have a preterm birth. About 10% of pregnant women having preterm labor actually deliver over the next week. With about 30% of these women, the preterm labor simply stops.

When preterm labor continues

If your preterm labor doesn’t let up, the next step is based on your baby’s health, and your health. When there’s a possibility your baby will do better with delaying delivery, your doctor may give you certain medications. These could include magnesium sulfate, tocolytics and corticosteroids.
  • Magnesium sulfate - You may receive this medication if you haven’t reached pregnancy week 32, if you’re at risk of delivering over the next 24 hours, or if you’re in preterm labor. This may reduce the risks of cerebral palsy that early preterm birth includes.
  • Tocolytics - These drugs may delay delivery for only up to 48 hours. This sometimes gives time for you to take magnesium sulfate or corticosteroids, or time for you to be sent on to a hospital offering specialized preterm baby care. Magnesium sulfate may also be used as a type of tocolytic drug.
  • Corticosteroids - These drugs cross the placenta and help speed up your baby’s lung development, as well as digestive organs and brain. They help the most between pregnancy weeks 24-32.

When labor doesn’t stop

If your labor doesn’t stop, and you’re headed towards an early delivery, a team of doctors will usually be involved. This may include a neonatologist. This type of doctor specializes in treating newborn problems. The type of care your baby will need depends on how early your child is born. High-level neonatal intensive care units, also called NICUs, specialize in preterm infant care.


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