• Risk Factors for Preterm Labor and Delivery

    A risk factor is something that increases your likelihood of getting a disease or condition.
    It is possible to have preterm labor with or without the risk factors listed below. However, the more risk factors you have, the greater your likelihood of having preterm labor. If you have a number of risk factors, ask your doctor what you can do to reduce your risk.
    Risk factors for preterm labor include:
    • A previous preterm birth
    • Low socioeconomic status
    • Non-white race
    • Age less than 18 or greater than 35 years
    • Premature rupture of the membranes
    • Carrying more than one baby
    • History of one or more spontaneous second-trimester abortions
    • Risky behaviors: Uterine problems:
      • Fibroids —This is a benign tumor in the wall of the uterus.
      • Abnormally shaped uterus—This does not allow enough space for the baby to grow.
      • Incompetent cervix—The cervix dilates too early in the pregnancy.
      • Exposure to diethylstilbestrol (DES)—Before its dangers were known, DES was given to pregnant women to decrease the risk of miscarriage; if your mother took DES while she was pregnant with you, your reproductive organs may be damaged. DES has not been used since the 1970s.
      Infections: Fetal causes:
      • Intrauterine fetal death
      • Intrauterine growth delay
      • Birth defects in the baby
    • Placental abruption (early separation of the placenta from the wall of the uterus; seen more with cocaine use )
    • Lifestyle issues and other causes:
      • Presence of a retained intrauterine device
      • Being underweight or obese prior to pregnancy
      • Poor eating habits
      • Physical, sexual, or emotional abuse
      • Lack of social support
      • Severe pregnancy-related anxiety
      • Working long hours with long periods of standing and/or doing physically strenuous work
    • Less than six months between giving birth and the beginning of the next pregnancy
    • Diabetes
    • High blood pressure
    • Pre-eclampsia (a combination of high blood pressure, water retention, and protein in the urine)
    • Clotting disorders (thrombophilia)
    • Vaginal bleeding after 16 weeks, or during more than one trimester
    • Being pregnant with a single fetus after in vitro fertilization (IVF)
    • Too much or too little fluid in the amniotic sac surrounding the baby
    • Surgery on your abdomen during pregnancy, such as removal of the appendix
    • Hormonal imbalance
    • Certain medicines (eg, benzodiazepines)
    • Overweight and obesity


    The American College of Obstetricians and Gynecologists. Assessment of risk factors for preterm birth. The American College of Obstetricians and Gynecologists Practice Bulletin, No.31. October 2001.

    Preterm labor. The American College of Obstetricians and Gynecologists website. Available at: http://www.acog.org/ . Accessed June 1, 2009.

    Preterm labor. March of Dimes website. Available at: http://www.marchofdimes.com/pnhec/188%5F1080.asp . Accessed September 22, 2005.

    Preterm labor. University of Michigan Health System website. Available at: http://www.med.umich.edu/ . Accessed September 23, 2005.

    A primer on preemies. American Academy of Family Physicians website. Available at: http://www.kidshealth.org/PageManager.jsp?dn=familydoctor&lic=44&cat%5Fid=20056&article%5Fset=21879&ps=104 . Accessed September 23, 2005.

    Research on preterm labor and premature birth. National Institute of Child Health & Human Development website. Available at: http://www.nichd.nih.gov/womenshealth/premature%5Fbirth.cfm . Accessed September 27, 2005.

    Weismiller DG. Preterm labor. American Family Physician website. Available at: http://www.aafp.org/afp/990201ap/593.html . Accessed September 26, 2005.

    7/21/2009 DynaMed's Systematic Literature Surveillance http://www.ebscohost.com/dynamed/what.php : Kramer MS, Lydon J, Séguin L, et al. Stress pathways to spontaneous preterm birth: the role of stressors, psychological distress, and stress hormones. Am J Epidemiol. 2009;169:1319-1326.

    1/22/2010 DynaMed's Systematic Literature Surveillance DynaMed's Systematic Literature Surveillance : Calderon-Margalit R, Qiu C, Ornoy A, Siscovick DS, Williams MA. Risk of preterm delivery and other adverse perinatal outcomes in relation to maternal use of psychotropic medications during pregnancy. Am J Obstet Gynecol. 2009;201(6):579.e1-8.

    8/23/2010 DynaMed's Systematic Literature Surveillance DynaMed's Systematic Literature Surveillance : McDonald SD, Han Z, Mulla S, Beyene J; Knowledge Synthesis Group. Overweight and obesity in mothers and risk of preterm birth and low birth weight infants: systematic review and meta-analyses. BMJ. 2010;341:c3428.

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