6 Signs of Preterm Labor and What Your Doctor Might Do Next

About 10% of American babies are born prematurely. Find out more about the causes of preterm labor, and learn how to identify the symptoms.

mom holding pregnant belly
Photo: Gajus/Shutterstock

Preterm labor happens when a pregnant person goes into labor before 37 weeks of pregnancy. About 10% of babies are born prematurely in America. The majority are delivered between 34 and 36 weeks, and most of them are healthy and need little or no special care after birth.

If a baby is born before 32 weeks, however, the prognosis is less optimistic. That's because premature delivery can result in negative health consequences such as low birth weight, vision or breathing difficulties, improper organ development, and learning disabilities.

Fortunately, though, if you're at risk for preterm labor, your doctor might be able to prolong your pregnancy, which gives your baby more time to develop. Keep reading to learn more about the causes and symptoms of preterm labor, as well as the prevention measures your doctor might take.

Warning Signs of Preterm Labor

You're probably experiencing a whole range of new sensations throughout your pregnancy. So how can you tell if you're feeling a simple stomach muscle cramp or a preterm contraction? Look for the following preterm labor symptoms and warning signs.

1. The contractions feel different than Braxton Hicks

After about 30 weeks of pregnancy, many pregnant people notice occasional uterine contractions. These non-labor contractions are called Braxton Hicks contractions, and they're normal and usually painless. They tend to occur when you're tired or exerting yourself, and they usually stop when you rest.

True preterm labor contractions come at regular intervals and progressively become more frequent or more painful; Braxton Hicks contractions do not. If your contractions continue no matter what you do, such as walk around, you're more likely to be having real contractions and not just Braxton Hicks, so be sure to call your doctor right away.

2. You feel a tightening in your belly at regular intervals

Anytime you're feeling something happening at what seems like regular intervals, time them. "The contractions may be painless, but they'll be predictable," says Siobhan Kubesh, a certified midwife with OBGYN North in Austin. "If they seem to be coming every 10 minutes or [more frequently], and you can predict when they'll start and stop, you need to call your health care provider."

3. You are spotting

You may have some bleeding or discharge of bloody mucus if you're experiencing preterm labor. "Any unexplained vaginal bleeding is a concern," Kubesh says. If the vaginal discharge changes, it's worth a quick call to your doctor.​

4. Your water breaks

If you experience a sudden gush of fluid from your vagina—an indication that your water may have broken—you should call your doctor immediately.​ Your water may also break and trickle, so if you have any fluid leaking, tell your doctor about it too.

While it's common to leak urine when pregnant (and mistake it for amniotic fluid), it's better to be safe if you have any doubts. There is a simple test your doctor can do to detect amniotic fluid, and they would much rather you double-check, just in case.

5. You feel pressure in your pelvis

"If there's a feeling of fullness in your vagina—if it feels like the baby's head is in the vagina—that's a symptom of preterm labor," Kubesh says.

6. You have back pain

Early contractions or premature labor can feel like back pain for some people. The back pain can come and go, or feel persistent.

Preterm Labor Risk Factors

Any pregnant person can experience preterm labor. However, certain factors increase a person's risk, including:

  • History of preterm labor or premature birth
  • Pregnancy with multiples
  • Smoking, drinking alcohol, or using drugs
  • Being underweight or overweight
  • Health conditions like diabetes, preeclampsia, or high blood pressure
  • Problems with the placenta, cervix, or uterus
  • Certain infections, including sexually transmitted infections (STIs)
  • Certain congenital disorders
  • Short interval between pregnancies (less than 12 months)
  • A shortened cervix

Diagnosing Preterm Labor

You're considered to be in preterm labor when you have uterine contractions every 10 minutes (or more often) as well as cervical changes (dilation, thinning, softening) prior to 37 weeks gestation. Your doctor might have difficulty determining whether you're truly in labor. If you're showing signs of preterm labor, they will likely tell you to go to the hospital (if you're not already there), where you can be monitored carefully.

Two tests—one that measures hormones in the saliva and another that measures vaginal secretions—can aid in diagnosing preterm labor. Doctors may do a swab of the cervix and vagina to test for a protein called fetal fibronectin.

"Fetal fibronectin (fFN) is a protein produced during pregnancy and functions as a biological glue, attaching the fetal sac to the uterine lining," the March of Dimes explains. "The presence of fFN during weeks 24–34 of a high-risk pregnancy, along with symptoms of labor, suggests that the 'glue' may be disintegrating ahead of schedule and alerts doctors to a possibility of preterm delivery." A vaginal ultrasound, which can accurately assess cervical dilation and other cervical changes, may help too.

If your doctor determines that you are in labor and you're fewer than 37 weeks into pregnancy, they'll probably attempt to halt it, unless it's not advisable for a medical reason. For instance, doctors might not stop preterm labor if they detect maternal high blood pressure, uterine bleeding because of a problem with the placenta, or fetal distress signals like a slowed heart rate.

Treating Preterm Labor

In some cases, preterm labor can be treated (and preterm birth prevented) to give your baby more time to grow. Your doctor will likely choose between natural and medicated approaches.

Treating preterm labor naturally

"The most common cause of preterm labor is dehydration or bladder infection, so rest and hydration can help it resolve on its own," Kubesh says. Pelvic rest—which means no sex, no vaginal exams, and anything else in the vagina—is often a must if you're experiencing preterm contractions.

In some cases, your doctor may suggest sewing your cervix shut (cervical cerclage) to help avoid premature birth or even resting with your head below the level of your body to further reduce stress on the cervix.

You may also be put on bed rest, at least temporarily, to avoid having gravity put pressure on your cervix. "Bed rest is one of the few things that has been shown to help prevent preterm birth," says Bart Putterman, M.D., an OB-GYN at Texas Children's Pavilion for Women in Houston.

To try to halt your contractions, your doctor will ask you to rest on your left side (this position increases blood flow to the uterus), and if you seem dehydrated, they may give you intravenous (IV) fluids. If your contractions stop and your cervix doesn't dilate during several hours of observation, you will probably be able to go home.

Treating preterm labor with medication

Your obstetrician may decide that attempting to postpone birth through medication is the appropriate course of action. While there is no established "right" time to start treatment with medication, many doctors recommend beginning once your cervix becomes 2 to 3 centimeters dilated. These drugs don't usually don't postpone labor for long (often not more than a couple of days), but even a short delay can make a lifesaving difference to your baby.

For example, your doctor can begin treatment with corticosteroid drugs between 24 and 34 weeks of pregnancy, which are aimed at preventing or lessening complications in preterm newborns. Corticosteroids speed the maturation of fetal organs and can help reduce the incidence of the two most serious complications of preterm birth: respiratory distress syndrome and bleeding in the brain.

Corticosteroids are given by injection and are most effective when administered at least 24 hours before delivery. Other medication options for treating preterm labor include magnesium sulfate (which might reduce the risk of cerebral palsy) and tocolytics (which temporarily slow contractions).

It's important to note, though, that preterm labor medications aren't without risks. "The medications can have dangerous side effects, especially when taken for an extended length of time," Dr. Putterman says. "We don't have a really good means for prolonging pregnancy, short of getting you off of your feet."

Will I Need to Deliver the Baby?

Your contractions are unlikely to stop on their own if your cervix is dilating. As long as you're between 34 and 37 weeks and the baby already is at least 5 pounds, 8 ounces, your doctor may decide not to delay labor. Babies born under these circumstances are very likely to do well even if they're born early.

If you have concerns about preterm contractions, speak with your doctor who can recommend strategies to help you safely get to 40 weeks.

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