All pregnancy you look forward to the big day. And maybe, when in the throes of heartburn and swollen feet and pregnancy insomnia, you hope the days fly by a teensy bit faster. But as much as we may want to rush to get to the big day, an early labor isn’t ideal.  Preterm labor—when contractions begin before 37 weeks of pregnancy—can sometimes lead to premature birth, which might impact a baby’s health. While early labor doesn’t always mean an early delivery, understanding what causes it, who’s at risk, and what signs to watch for can help you feel more prepared and in control.

What causes preterm labor?

While experts can’t pinpoint one single cause of preterm labor—research suggests that there are multiple factors at play—some common triggers include:

• Inflammation and infections: Conditions like bacterial vaginosis can cause inflammation that may lead to labor.
• Placental abruption: When the placenta detaches too soon, it can cause contractions.
• An overdistended uterus: If you have too much amniotic fluid (polyhydramnios) or are carrying multiples, your uterus might be stretched too far.
• Cervical insufficiency: This condition, characterized by a weak or short cervix, can lead to the cervix opening too early. For about 1% of parents who experience preterm labor, this is the cause. 
• Hormonal changes: Some hormonal shifts may signal the body to start labor early.

What are signs and symptoms of preterm labor?

Knowing what to look out for can make all the difference. Here are some common signs that can tip you off about preterm labor.

Preterm Labor Symptoms

• Frequent contractions (more than four per hour) that don’t go away with rest
• Lower back pain that feels persistent or dull
• Pelvic pressure—it feels like the baby is pushing down
• Abdominal cramping (with or without diarrhea)
• Vaginal spotting or bleeding
• A change in pregnancy discharge, such as an increase or a watery consistency
• Your water breaking early (rupture of membranes)

If you notice any of these symptoms, reach out to your healthcare provider right away. Even if birth isn’t on the horizon, it’s always better to check to be sure!

Who is at risk for preterm labor?

While preterm labor can happen to anyone, certain factors can make it more likely.

Preterm Labor Risk Factors

• A history of preterm birth: If you’ve had a preterm baby before, your risk increases for future pregnancies.
• Carrying multiples: Twins, triplets, or more put added strain on the uterus.
• Short intervals between pregnancies: Less than six months between pregnancies can increase the risk.
• Infections: Urinary tract infections, bacterial vaginosis, and some sexually transmitted infections (STIs) have been linked to preterm labor.
• Chronic conditions: High blood pressure, diabetes, and thyroid disorders can contribute.
• Structural issues: Uterine abnormalities or cervical insufficiency can lead to early labor.
• Lifestyle factors: Smoking, substance use, and excessive alcohol consumption are significant risk factors.
• High stress levels: Chronic stress or exposure to domestic violence can increase the likelihood of preterm labor.
• Being underweight or overweight: Both extremes can affect pregnancy outcomes. (Learn more about pregnancy weight gain.)

Will preterm labor affect your baby?

Not all preterm labor results in preterm birth, but when babies are born early, their challenges depend on how premature they are:

• Moderate to late preterm (32 weeks to 37 weeks): Some mild breathing or feeding difficulties may occur, but most babies do well with a little extra care.
• Very preterm (28 weeks to less than 32 weeks): Babies may need more medical support, especially for their lungs and immune system.
• Extremely preterm (less than 28 weeks): These babies often require intensive care, but many go on to thrive with medical intervention.

While an early birth can be scary, medical advancements have significantly improved outcomes for preterm babies.

How can you prevent preterm labor?

While preterm labor isn’t always preventable, you can lower your risk:

• Go to all prenatal checkups so your provider can monitor your health.
• Manage chronic conditions like high blood pressure and diabetes with your doctor’s help.
• Avoid smoking, alcohol, and drugs, as they increase the risk of early labor.
• Keep a healthy weight and eat a well-balanced diet. (Here are some tips for eating during pregnancy!)
• Find ways to reduce stress, whether that’s through relaxation techniques, therapy, meditation, or prenatal yoga.
• Ask about progesterone therapy if you’ve had a previous preterm birth.

What should you do if you suspect preterm labor?

If you think you’re in preterm labor, these are the steps you should take:

• Call your doctor right away to go over your symptoms.
• Rest and drink water, since dehydration can sometimes cause contractions.
• Track your contractions—time how often they happen and how strong they feel.
• Head to the hospital if your doctor recommends it. You might get medications to slow contractions, help your baby’s lungs mature, or address any complications.

Preterm Labor: Final Thoughts

Facing the possibility of preterm labor can feel overwhelming, but having the right information empowers you. Understanding the causes, signs, and risks of preterm labor can help you take action and feel more in control. If you ever have concerns about your pregnancy, don’t hesitate to reach out to your healthcare provider—they’re there to help you every step of the way.

More on Labor and Delivery:

• Affirmations to Prepare for Childbirth
• False Labor Signs: Are You in Labor or Not?
• Your Options for Pain Relief During Labor
• Natural Ways to Induce Labor: Fact vs. Fiction

 

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REFERENCES

• American College of Obstetricians and Gynecologists: Preterm Labor and Birth
• World Health Organization: Preterm Birth Fact Sheet
• Mayo Clinic: Preterm Labor: Symptoms & Causes
• National Institutes of Health (NIH): Preterm Birth and Prolonged Labor Influenced by Progesterone Balance
• National Institute of Child Health and Human Development: Who is at Risk for Preterm Labor?
• Cleveland Clinic: Premature Labor
• Yale Medicine: Cervical Insufficiency
• Preterm birth, prolonged labor influenced by progesterone balance, National Institutes of Health (NIH) News Release, March 11, 2021.
• Uterine overdistention induces preterm labor mediated by inflammation: observations in pregnant women and nonhuman primates, American Journal of Obstetrics and Gynecology, December 2015
• American Academy of Family Physicians: Preterm Labor Management
• American College of Obstetricians and Gynecologists: Prediction and Prevention of Spontaneous Preterm Birth
• MedlinePlus: Preterm Labor: What to Do

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Disclaimer: The information on our site is NOT medical advice for any specific person or condition. It is only meant as general information. If you have any medical questions and concerns about your child or yourself, please contact your health provider.