Preterm labor occurs between the 20th and 37th week of pregnancy. This labor includes both uterine contractions and cervical changes.
A full-term pregnancy lasts 38-42 weeks but preterm labor can lead to early delivery. Infants born before 37 weeks are considered premature.
In most cases, the cause is of preterm labor is unknown.
Some preterm labor is associated with preterm premature rupture of membranes (PPROM). PPROM is the rupture of both the amniotic sac and chorion membranes. It generally occurs at least 1 hour before labor begins.
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The chance of preterm-labor is greatest in women under the age of 18 years or over 35 years. Other maternal factors that may increase the chance of preterm labor include: Low socioeconomic status
prenatal care and
Being underweight or
before becoming pregnant
Physical, sexual, or emotional abuse
anxietyDiabetesHigh blood pressureCeliac diseaseClotting disordersHormonal imbalanceCertain medications or exposure to diethylstilbestrol (DES)SmokingIllicit drug useAlcohol use
Pregnancy complications that may increase your risk of preterm labor include: Pre-eclampsia
(hypertension)Placental abruption(separation from the uterus)Premature rupture of the membranesCarrying more than one babyVaginal bleeding after 16 weeks, or during more than one trimester
Infection in the cervix, uterus, vagina, or
sexually transmitted diseases
Being pregnant with a single fetus after
in vitro fertilization
Presence of a retained intrauterine device (IUD)Incompetent cervixToo much or too little fluid surrounding the babySurgery on your abdomen during pregnancyAmniotic fluid infectionIntrauterine fetal deathIntrauterine growth delayBirth defects in the baby
Other factors associated with an increased chance of preterm labor include: History of 1 or more spontaneous second-trimester miscarriagesLess than 6 months between giving birth and the beginning of the next pregnancyA previous preterm birthUterine fibroidsAbnormally shaped uterusPrevious weight reduction surgeryProcedures to remove abnormal cervical cells
Symptoms may include: Abdominal pain that feels something like menstrual crampsDull pain in the lower backPressure in the pelvis and tightening in the thighsVaginal bleeding or spotting, or watery discharge
You will be asked about your symptoms and medical history. A physical exam will be done. Your doctor may recommend tests to check your cervix and membranes have ruptured. An
will help your doctor see internal structures and the baby.
Fluids in the cervix will also be tested for sign of labor progression. A tocometer may be placed to help monitor contractions.
Treatment will depend on your baby's development, especially the growth of the lungs. If your doctor believes the baby is ready, the labor may be allowed to continue. If the baby is not ready to be delivered, your doctor may try to stop the labor. Stopping labor is a complicated process and may not always work.
Some treatment options may include: Tocolytics—may delay labor for a few daysCorticosteroids—to help the baby's lungs developAntibiotics—if an infection is suspected or present
To help reduce your chance of preterm labor: Get the proper prenatal care throughout your entire pregnancy.Eat a healthy, balanced diet with plenty of fruits, vegetables, and whole grains.Consider adding fish to your diet. It may reduce the risk of preterm birth.Drink plenty of water.Avoid smoking, alcohol, and drugs.Keep chronic diseases under control.Stay active during your pregnancy. Your doctor can give you exercise guidelines that are right for you.If you are at high-risk for premature birth, talk to your doctor about progesterone therapy or cervical cerclage, a procedure that closes the cervix with sutures.
The American Congress of Obstetricians and Gynecologists. Management of stillbirth.
March 2009;102. Reaffirmed 2014.
Hall R. Prevention of premature birth: Do pediatricians have a role?
Premature labor. American Pregnancy Association website. Available at:
http://americanpregnancy.org/labor-and-birth/premature-labor. Updated August 2015. Accessed March 14, 2016
1/22/2010 DynaMed Plus Systematic Literature Surveillance
http://www.dynamed.com/topics/dmp~AN~T115273/Preterm-labor: Calderon-Margalit R, Qiu C, et al. Risk of preterm delivery and other adverse perinatal outcomes in relation to maternal use of psychotropic medications during pregnancy.
Am J Obstet Gynecol
8/23/2010 DynaMed Plus Systematic Literature Surveillance
http://www.dynamed.com/topics/dmp~AN~T115273/Preterm-labor: McDonald SD, Han Z, et al.; Knowledge Synthesis Group. Overweight and obesity in mothers and risk of preterm birth and low birth weight infants: systematic review and meta-analyses.
4/24/2014 DynaMed Plus Systematic Literature Surveillance
http://www.dynamed.com/topics/dmp~AN~T115273/Preterm-labor: Leventakou V, Roumeliotaki T, et al. Fish intake during pregnancy, fetal growth, and gestational length in 19 European birth cohort studies. Am J Clin Nutr. 2014 Mar;99(3):506-16.
4/29/2014 DynaMed Plus Systematic Literature Surveillance
http://www.dynamed.com/topics/dmp~AN~T115273/Preterm-labor: 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.
Last reviewed March 2016 by Marcie L. Sidman, MD
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.
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