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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.

Non-white women under the 18 years or over 35 years have an increased risk of preterm labor. Other factors that may increase your risk include:

Current and past pregnancy:

  • A previous preterm birth
  • Pre-eclampsia
  • Placental abruption
  • Premature rupture of the membranes
  • Carrying more than 1 baby
  • Vaginal bleeding after 16 weeks, or during more than one trimester
  • Being pregnant with a single fetus after in vitro fertilization (IVF)
  • Less than 6 months between giving birth and the beginning of the next pregnancy
  • Presence of a retained intrauterine device
  • History of 1 or more spontaneous second-trimester abortions
  • Too much or too little fluid in the amniotic sac surrounding the baby
  • Surgery on your abdomen during pregnancy

Fetal causes:

  • Intrauterine fetal death
  • Intrauterine growth delay
  • Birth defects in the baby

Risky behaviors:

History of reproductive organ problems:

  • Uterine fibroids
  • Abnormally shaped uterus
  • Incompetent cervix—the cervix dilates too early in the pregnancy
  • Infection in the cervix, uterus, or vagina
  • Amniotic fluid infection
  • Procedures to remove abnormal cervical cells
  • Urinary tract infections
  • Sexually transmitted diseases
  • 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.

Social causes:

  • Low socioeconomic status
  • Lack of prenatal care
  • Lack of social support

Physical and psychological causes:

  • Being underweight or obese prior to pregnancy
  • A previous bariatric surgery
  • Physical, sexual, or emotional abuse
  • Severe depression or anxiety
  • Diabetes
  • High blood pressure
  • Clotting disorders
  • Hormonal imbalance
  • Certain medications

Revision Information

  • Reviewer: Andrea Chisholm
  • Review Date: 06/2013 -
  • Update Date: 00/80/2014 -
  • Prematurity. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated April 18, 2013 . Accessed April 23, 2013.

  • Preterm labor. The American Congress of Obstetricians and Gynecologists website. Available at: http://www.acog.org/~/media/For%20Patients/faq087.pdf?dmc=1&ts=20130423T0923201528. Accessed April 23, 2013.

  • Preterm labor. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated March 15, 2013 . Accessed April 23, 2013.

  • Preterm labor and birth. March of Dimes website. Available at: http://www.marchofdimes.com/pregnancy/preterm%5Findepth.html. Updated September 2012. Accessed April 23, 2013.

  • Who is at risk for preterm labor and birth? National Institute of Child Health & Human Development website. Available at: hhttp://www.nichd.nih.gov/health/topics/preterm/conditioninfo/Pages/who%5Frisk.aspx. Updated November 30, 2012. Accessed April 23, 2013.

  • 7/21/2009 DynaMed's Systematic Literature Surveillance http://www.ebscohost.com/dynamed: 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 http://www.ebscohost.com/dynamed: 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 http://www.ebscohost.com/dynamed: 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.

  • 11/19/2013 DynaMed's Systematic Literature Surveillance http://www.ebscohost.com/dynamed: Roos N, Neovius M, et al. Perinatal outcomes after bariatric surgery: nationwide population based matched cohort study. BMJ. 2013;347:f6460.

  • 4/29/2014 DynaMed's Systematic Literature Surveillance http://www.ebscohost.com/dynamed: Huybrechts KF, Sanghani RS, et al. Preterm birth and antidepressant medication use during pregnancy: a systematic review and meta-analysis. PLoS One. 2014 Mar 26;9(3):e92778.

  • 8/5/2014 DynaMed's Systematic Literature Surveillance http://www.ebscohost.com/dynamed: Conner SN, Frey HA, et al. Loop electrosurgical excision procedure and risk of preterm birth: a systematic review and meta-analysis. Obstet Gynecol. 2014;123(4):752-761.