Preterm labor and preterm birth: Are you at risk?

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What are preterm labor and preterm birth?

Preterm labor is labor that begins early, before 37 weeks of pregnancy. Labor is the process your body goes through to give birth to your baby. Preterm labor can lead to preterm birth. Preterm birth is when your baby is born early, before 37 weeks of pregnancy. Your baby needs about 40 weeks in the womb to grow and develop before birth.

Babies born before 37 weeks of pregnancy are called preterm. Preterm babies can have serious health problems at birth and later in life. About 1 in 10 babies is born preterm each year in the United States.

What are the signs and symptoms of preterm labor?

Signs of a condition are things someone else can see or know about you, like you have a rash or you’re coughing. Symptoms are things you feel yourself that others can’t see, like having a sore throat or feeling dizzy. Learn the signs and symptoms of preterm labor so you can get help quickly if they happen to you.

If you have even one of these signs and symptoms of preterm labor, call your provider right away:

• Change in your vaginal discharge (watery, mucus or bloody) or more vaginal discharge than usual
• Pressure in your pelvis or lower belly, like your baby is pushing down
• Constant low, dull backache
• Belly cramps with or without diarrhea
• Regular or frequent contractions that make your belly tighten like a fist. The contractions may or may not be painful.
• Your water breaks

When you see your provider, he may do a pelvic exam or a transvaginal ultrasound to see if your cervix has started to thin out and open for labor. Your cervix is the opening to the uterus (womb) that sits at the top of the vagina (birth canal). A transvaginal ultrasound is done in the vagina instead of on the outside of your belly. Like a regular ultrasound, it uses sound waves and a computer to make a picture of your baby. If you’re having contractions, your provider monitors them to see how strong and far apart they are. You may get other tests to help your provider find out if you really are in labor.

If you’re having preterm labor, your provider may give you treatment to help stop it. Or you may get treatment to help improve your baby’s health before birth. Talk to your provider about which treatments may be right for you.

Are you at risk for preterm labor and preterm birth?

We don’t always know for sure what causes preterm labor and preterm birth. Sometimes labor starts on its own without warning. Even if you do everything right during pregnancy, you can still give birth early.

We do know some things may make you more likely than others to have preterm labor and preterm birth. These are called risk factors. Having a risk factor doesn’t mean for sure that you’ll have preterm labor or give birth early. But it may increase your chances. Talk to your health care provider about what you can do to help reduce your risk.

Because many preterm babies are born with low birthweight, many risk factors for preterm labor and preterm birth are the same as for having a low-birthweight baby. Low birthweight is when a baby is born weighing less than 5 pounds, 8 ounces.

These three risk factors make you most likely to have preterm labor and give birth early:

1. You’ve had a preterm baby in the past. 
2. You’re pregnant with multiples (twins, triplets or more).  
3. You have problems with your uterus or cervix now or you’ve had them in the past. Your uterus (also called the womb) is where your baby grows inside you.

Medical risk factors before pregnancy for preterm labor and preterm birth

• Being underweight or overweight before pregnancy. This can include having an eating disorder, like anorexia or bulimia.  
• Having a family history of preterm birth. This means someone in your family (like your mother, grandmother or sister) has had a preterm baby. If you were born preterm, you’re more likely than others to give birth early. 
• Getting pregnant again too soon after having a baby. For most women it’s best to wait at least 18 months before getting pregnant again. Talk to your provider about the right amount of time for you.

Medical risk factors during pregnancy for preterm labor and preterm birth

Having certain health conditions during pregnancy can increase your risk for preterm labor and preterm birth, including:

• Connective tissue disorders, like Ehlers-Danlos syndromes (also called EDS) and vascular Ehlers-Danlos syndrome (also called vEDS). Connective tissue is tissue that surrounds and supports other tissues and organs. EDS can cause joints to be loose and easy to dislocate; skin to be thin and easily stretched and bruised; and blood vessels to be fragile and small. It also can affect your uterus and intestines. vEDS is the most serious kind of EDS because it can cause arteries and organs (like the uterus) to rupture (burst). EDS and vEDS are genetic conditions that can be passed from parent to child through genes.
• Diabetes. Diabetes is when your body has too much sugar (called glucose) in your blood.
• High blood pressure and preeclampsia. High blood pressure (also called hypertension) is when the force of blood against the walls of the blood vessels is too high. This can stress your heart and cause problems during pregnancy. Preeclampsia is a kind of high blood pressure impacting some women during or right after pregnancy. If not treated, it can cause serious problems and even death.
• Infections, including sexually transmitted infections (also called STIs) and infections of the uterus, urinary tract or vagina
• Intrahepatic cholestasis of pregnancy (also called ICP). ICP is the most common liver condition that happens during pregnancy.
• Thrombophilias. These are conditions that increase your risk of making abnormal blood clots.

Other medical risk factors during pregnancy include:

• Getting late or no prenatal care. Prenatal care is medical care you get during pregnancy.
• Not gaining enough weight during pregnancy. This can include having an eating disorder, like anorexia or bulimia.  
• Bleeding from the vagina in the second or third trimester 
• Preterm premature rupture of the membranes (also called PPROM). Premature rupture of membranes (also called PROM) is when the amniotic sac around your baby breaks (your water breaks) before labor starts. PPROM is when this happens before 37 weeks of pregnancy. If you have any fluid leaking from your vagina, call your provider and go to the hospital.  
• Being pregnant after in vitro fertilization (also called IVF). IVF is a fertility treatment used to help women get pregnant.  
• Being pregnant with a baby who has certain birth defects, like heart defects or spina bifida. Birth defects are health conditions that are present at birth. They change the shape or function of one or more parts of the body. Birth defects can cause problems in overall health, how the body develops or how the body works. Spina bifida is a birth defect of the spine.

Risk factors in your everyday life for preterm labor and preterm birth

• Smoking, drinking alcohol, using street drugs or abusing prescription drugs.
• Having a lot of stress in your life. 
• Low socioeconomic status (also called SES).  SES is a combination of things like your education, your job and your income (how much money you make).
• Domestic violence. This is when your partner hurts or abuses you. It includes physical, sexual and emotional abuse. 
• Working long hours or having to stand a lot
• Exposure to air pollution, lead, radiation and chemicals in things like paint, plastics and secondhand smoke. Secondhand smoke is smoke from someone else’s cigarette, cigar or pipe.

Age and race as risk factors for preterm labor and preterm birth

Being younger than 17 or older than 35 makes you more likely than other women to give birth early. In the United States, black women are more likely to give birth early. Almost 17 percent of black babies are born preterm each year. Just more than 10 percent of American Indian/Alaska Native and Hispanic babies are born early, and less than 10 percent of white and Asian babies. We don’t know why race plays a role in preterm birth; researchers are working to learn more about it.  

Can you reduce your risk for preterm labor and preterm birth?

Yes, you may be able to reduce your risk for early labor and birth. Some risk factors are things you can’t change, like having a preterm birth in a previous pregnancy. Others are things you can do something about, like quitting smoking.

Here’s what you can do to reduce your risk for preterm labor and preterm birth:

• Get to a healthy weight before pregnancy and gain the right amount of weight during pregnancy. Talk to your provider about the right amount of weight for you before and during pregnancy.
• Don’t smoke, drink alcohol, use street drugs or abuse prescription drugs. Ask your provider about programs that can help you quit.
• Go to your first prenatal care checkup as soon as you think you’re pregnant. During pregnancy, go to all your prenatal care checkups, even if you’re feeling fine. Prenatal care helps your provider make sure you and your baby are healthy.
• Get treated for chronic health conditions, like high blood pressure, diabetes, depression and thyroid problems. Depression is a medical condition in which strong feelings of sadness last for a long time and interfere with your daily life. It needs treatment to get better. The thyroid is a gland in your neck that makes hormones that help your body store and use energy from food.
• Protect yourself from infections. Talk to your provider about vaccinations that can help protect you from certain infections. Wash your hands with soap and water after using the bathroom or blowing your nose. Don’t eat raw meat, fish or eggs. Have safe sex. Don’t touch cat poop.
• Reduce your stress. Eat healthy foods and do something active every day. Ask family and friends for help around the house or taking care of other children. Get help if your partner abuses you. Talk to your boss about how to lower your stress at work.
• Wait at least 18 months between giving birth and getting pregnant again. Use birth control until you’re ready to get pregnant again. If you’re older than 35 or you’ve had a miscarriage or stillbirth, talk to your provider about how long to wait between pregnancies. Miscarriage is the death of a baby in the womb before 20 weeks of pregnancy. Stillbirth is the death of a baby in the womb after 20 weeks of pregnancy.  

Last reviewed: February 2024

See also: Signs and symptoms of preterm labor infographic