11 Premature Birth Risk Factors

What are your chances of having a preemie?

Baby in NICU

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Thinking about the risks of having a premature baby probably won't be your first reaction to a pregnancy test turned positive. There are many more exciting things to do when you find out that you're pregnant. Tasks like choosing nursery decorations, registering for all things baby, picking a name, and planning a homecoming party are all parts of the thrill of expecting.

However, planning for a healthy pregnancy is another important part of expectant parenthood. Premature birth is a major health problem and the rates are increasing.

Here's some of what researchers know (and don't know) about who is most at risk for a preterm delivery, how to diagnose preterm labor as early as possible, and how to prevent birth when labor starts early.

Risk Factors for Premature Birth

Some, but not all, of the risk factors for premature delivery can be reduced if not eliminated altogether. Talk to your doctor or midwife about your individual risk and what you can do to minimize it.

  • Age. Pregnant people under age 18 and over the age of 30 have the greatest risk of going into labor early. If your age puts you at increased risk for preterm labor, you will need to reduce any other risk factors that you have.
  • Alcohol use. No amount of alcohol is safe while you are pregnant. Preterm delivery is just one of the many risks associated with drinking alcohol while you are pregnant.
  • Chronic high blood pressure. Having high blood pressure before you got pregnant puts you at higher risk for early birth. Developing a condition called preeclampsia also increases the risk.
    • Early prenatal care can help doctors and midwives to diagnose and treat preeclampsia or other hypertensive disorders of pregnancy early, reducing the risk of complications.
  • Diabetes. If you have type 1 or type 2 diabetes before pregnancy, you are more likely to deliver your baby early. Good blood sugar control can be hard to maintain during pregnancy, even for pregnant people who have been well controlled for many years.
    • Keeping blood sugar within a healthy range can reduce the risk of premature birth and other risks of diabetes during pregnancy.
  • Lack of prenatal care. The later your prenatal care begins, the greater your risk of health complications during pregnancy. Make a doctor’s appointment as soon as you find out that you are pregnant. A lack of or delayed prenatal care are both associated with preterm delivery.
  • Multiple pregnancies. Pregnant people who are carrying multiples (twins, triplets, or more) are at an increased risk for early delivery, as well as other complications.
    • Learning more about carrying multiples can help you work with your doctors to ensure a healthy pregnancy and safe delivery.
  • Poor nutrition. Pregnant people with an extremely low body mass index have a higher risk of preterm delivery. Pregnant people with generally poor nutritional status also have a greater risk.
    • Maintain a healthy weight and eat a balanced, nutritious diet while you are pregnant.
  • Prior premature birth. Having one premature baby puts you at an increased risk of having another preemie. This risk also increases if your pregnancies are close together or if you have additional risk factors.
    • Controlling other risk factors can help reduce the risk of having a second preterm birth.
  • Smoking. Smoking cigarettes is one of the greatest risks of premature delivery, but it's also one that you can control.
    • Aside from the risk of premature birth, there are other health risks to a fetus and newborn associated with nicotine and cigarette smoke. Talk to your doctor or midwife if you need help quitting.
  • Untreated infection. Infections, especially those of the uterus and urinary tract, can increase the risk of premature birth.
    • Having a high white blood cell count (a marker of infection) is the best predictor of preterm birth from 22 to 27 weeks gestation.
  • Uterine or cervical problems. Uterine infections, cervical insufficiency, and placental abruption can all lead to preterm labor and birth.
    • The treatment for each condition varies, but often includes bed rest, cerclage, medication, or scheduled early delivery.
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Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  • Centers for Disease Control and Prevention. "CDC Features: Premature Birth."

  • Esplin, MD, Michael S., O’Brien, Ph.D., Elizabeth, Fraser, MPH, Alison, Kerber, Ph.D., Richard A., Clark, MD, Erin, Simonsen, RN MSPH, Sara Ellis, Holmgren, MD, Calla, Mineau, Ph.D., Geraldine P., Varner, MD, Michael W. “Estimating Recurrence of Spontaneous Preterm Delivery.” Obstetrics and Gynecology Sept 2008 112:516-523.

  • Hill, MSca, Jacquelyn L., Cambell, Ph.D., Karen, Zou, Ph.D., Guang Yong, Challis, Ph.D., John R.G., Reid, PhDc, Gregor, Chisaka, MDde, Hiroshi, and Bocking, MD, Allen. “Prediction of Preterm Birth in Symptomatic Women Using Decision Tree Modeling for Biomarkers." American Journal of Obstetrics & Gynecology April 2008 198:e1-e9.

  • Medline Plus Medical Encyclopedia. "Premature Infant." 
  • Spong, MD, Catherine Y. “Prediction and Prevention of Recurrent Spontaneous Preterm Birth.” Obstetrics and Gynecology August 2007 110:405-415.

By Cheryl Bird, RN, BSN
Cheryl Bird, RN, BSN, is a registered nurse in a tertiary level neonatal intensive care unit at Mary Washington Hospital in Fredericksburg, Virginia.