What Is Preterm Labor? Can Medications Make It More Likely to Happen?

• Preterm labor can happen very suddenly. If you experience symptoms of preterm labor, seek medical attention right away.

• There are treatments and ways to help prevent preterm labor. Consider talking with your obstetrician-gynecologist (OB-GYN) to understand your options.

Preterm birth is a global health concern — about 15 million babies are born preterm every year. In 2020, preterm birth affected 1 in 10 newborn babies in the U.S. Preterm birth is also the most common cause of newborn death and long-term nervous system concerns in children.

On November 17 of every year, World Prematurity Day takes place across the world to raise awareness for preterm labor and birth. 

In this article, we’ll discuss preterm labor — its signs and symptoms, its causes and risk factors, and ways to treat or prevent this condition.

What are the signs and symptoms of preterm labor?

A full-term pregnancy usually lasts about 40 weeks, which is slightly more than 9 months. Preterm labor — or labor that happens before 37 weeks of pregnancy — tends to happen unexpectedly. But preterm labor signs are very similar to full-term labor signs, which include:

• Contractions (feeling of stomach tightening) about every 10 minutes

• Higher amounts of leaky fluid or bleeding from the vagina

• Dull pain in the lower back

• Pressure in the lower stomach

• Stomach cramps

If you have these types of symptoms, you might be experiencing preterm labor.

But preterm labor doesn’t automatically lead to preterm birth. Sometimes, preterm labor can stop on its own — or treatments can be given to try and delay birth. If you think you’re having preterm labor, call your obstetrician-gynecologist (OB-GYN) and go to the hospital as soon as you can. 

What are some causes or risk factors of preterm labor?

Experts are unsure about the specific causes of preterm labor. In fact, some women who have preterm births have no known risk factors that raise the chances of it happening.

But healthcare providers tend to consider women with the following factors at higher risk of preterm labor or birth:

• Prior history of preterm birth

• Pregnancy with twins, triplets, or more

• Early dilation (widening) of the cervix

• Prior procedure performed on the cervix

• Short cervix

Some of the following medical conditions or situations may also raise a woman’s risk of preterm labor or birth:

• Abnormal placenta, called placenta previa

• Blood clotting problems

• Back-to-back pregnancies (less than 6 months in between birth and beginning of next pregnancy)

• Diabetes

• High blood pressure

• Vaginal or urinary tract infections during pregnancy

• Pregnancy through in vitro fertilization (IVF)

• Prior history of a cesarean (C-section) delivery

• Unhealthy weight before pregnancy

• Development problems of the unborn baby

• Vaginal bleeding during pregnancy

Some other risk factors may include:

• African American or American Indian/Alaska Native race

• Younger than 18 years or older than 35 years

• Alcohol, tobacco, or other substance use

• Dietary deficiencies — like low vitamin D

• Domestic violence

• Late or no prenatal care

• Little social support

• Long periods of standing while working

• Stress

Besides these, some substances and medications can raise the risk of preterm labor or birth. Let’s talk about these next.

Which medications raise the risk of preterm labor?

As mentioned, certain medications and substances can worsen the risk for preterm labor.

For example, heavily drinking alcohol and smoking cigarettes during pregnancy can raise the risk for preterm labor. Other substances — like cocaine, heroin, or marijuana — can also worsen the odds. 

Below, we’ll discuss prescription medications that may be a risk for preterm labor.

Benzodiazepines

Benzodiazepine medications are short-term treatment options for anxiety and other conditions. Examples of benzodiazepines include alprazolam (Xanax) and lorazepam (Ativan). In general, taking benzodiazepines raises the risk of preterm birth.

Opioids

Opioids — like codeine, morphine (MS Contin, Kadian), and oxycodone (Roxicodone) — are often used to relieve pain. Taking opioids during pregnancy is linked to a higher risk of premature birth.

If you use opioids often or live with opioid use disorder (OUD), consider talking to your healthcare provider about Subutex (buprenorphine) or Suboxone (buprenorphine/naloxone). These medications can help treat OUD. They can also treat pain, but they’re weaker than other common opioids. Recent data suggests these two opioid medications might be better options during pregnancy.

Selective serotonin reuptake inhibitors (SSRIs)

In the past, SSRIs — like fluoxetine (Prozac), paroxetine (Paxil), and sertraline (Zoloft) — have been linked to a higher likelihood of preterm birth. In general, there are some risks with starting a new SSRI during pregnancy, but these risks are rare. Treating mental health symptoms like depression is also important. The risks of using SSRIs are low, especially if you start taking one before you become pregnant. 

As a disclaimer, this isn’t an all-inclusive list. There are several other medications that should be avoided during pregnancy. If you have questions about medications you take, talk with your healthcare provider or pharmacist.

What treatments are available to prevent preterm labor?

If you’re at high risk of having preterm labor or birth, reach out to your OB-GYN — a doctor who specializes in women’s health — to discuss possible treatments. This may include the following:

• Cerclage: If you have a short cervix and prior history of a preterm birth, then cerclage is a potential option. It’s a procedure to close the cervix with one or more stitches.

• Progesterone shots: A shot called Makena (hydroxyprogesterone caproate) is a possible choice to prevent preterm birth. If you previously had a preterm birth and you’re pregnant with another child, you may get this. If so, you’ll usually start taking it between 16 to 20 weeks of your pregnancy.

• Vaginal progesterone: If you haven’t had a preterm birth but you have a short cervix at 24 weeks or earlier during your pregnancy, your OB-GYN may suggest using a vaginal gel (Crinone) or suppository (Endometrin).

If you’re actively experiencing preterm labor, hospital staff will likely use different medications. Some medications aim to help the baby develop, some help prevent infections, and others aim to stop or slow down contractions. You might also get other medications if necessary.

Is there anything else I can do to prevent preterm labor?

There are a few ways you can help prevent preterm labor while pregnant. There’s a strong focus on lessening the impact of risk factors that are connected to preterm labor and birth. Consider the following:

• Avoid secondhand smoke, lead, and certain harmful chemicals

• Avoid alcohol, tobacco, marijuana, cocaine, and heroin use

• Limit benzodiazepine and opioid use if possible

• Eat a healthy diet

• Have a good social support network

• Lessen body strain from standing all day

• Maintain a healthy weight that isn’t underweight or overweight

• Try stress reduction practices exercises

• Try to prevent urinary tract infections (UTIs) and sexually transmitted infections (STIs)

• Start receiving prenatal care as soon as possible

Why trust our experts?

Written by:

Ross Phan, PharmD, BCACP, BCGP, BCPS

Ross Phan is a board-certified clinical pharmacist. She has roughly two decades of healthcare experience — with most of her experience being pharmacy related.

Edited by:

Joshua Murdock, PharmD, BCBBS

Joshua Murdock, PharmD, BCBBS, is a licensed pharmacist in Arizona, Colorado, and Rhode Island. He has worked in the pharmacy industry for more than 10 years and currently serves as a pharmacy editor for GoodRx.

Reviewed by:

Amy B. Gragnolati, PharmD, BCPS

Amy Gragnolati, PharmD, BCPS, is a pharmacy editor for GoodRx. Amy currently holds her pharmacist license in Georgia and California.

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