Official reprint from UpToDate®
www.uptodate.com ©2017 UpToDate®

Diagnosis of preterm labor and overview of preterm birth

Charles J Lockwood, MD, MHCM
Section Editor
Susan M Ramin, MD
Deputy Editor
Vanessa A Barss, MD, FACOG


Identifying women with preterm contractions who will actually deliver preterm is an inexact process, even though preterm labor is one of the most common reasons for hospitalization of pregnant women. Accurate identification of women truly in preterm labor allows appropriate application of interventions that can improve neonatal outcome: antenatal corticosteroid therapy, group B streptococcal infection prophylaxis, magnesium sulfate for neuroprotection, and transfer to a facility with an appropriate level nursery (if necessary). On the other hand, accurate triage of women not actually in preterm labor can avoid performance of unnecessary interventions and associated costs for the 20 to 50 percent of patients with suspected preterm labor who will go on to deliver at term without tocolytic therapy [1].

This topic will describe our approach to the diagnostic evaluation of women who present with possible preterm labor and provide an overview of issues related to preterm birth. Treatment of preterm labor is discussed separately. (See "Inhibition of acute preterm labor".)


Pathogenesis — The pathophysiology of preterm labor involves four primary pathogenic processes that result in a final common pathway ending in spontaneous preterm labor and delivery:

Activation of the maternal or fetal hypothalamic-pituitary-adrenal axis associated with either maternal anxiety and depression or fetal stress



Subscribers log in here

To continue reading this article, you must log in with your personal, hospital, or group practice subscription. For more information or to purchase a personal subscription, click below on the option that best describes you:
Literature review current through: Jan 2017. | This topic last updated: Fri Feb 17 00:00:00 GMT+00:00 2017.
The content on the UpToDate website is not intended nor recommended as a substitute for medical advice, diagnosis, or treatment. Always seek the advice of your own physician or other qualified health care professional regarding any medical questions or conditions. The use of this website is governed by the UpToDate Terms of Use ©2017 UpToDate, Inc.
  1. Haas DM, Imperiale TF, Kirkpatrick PR, et al. Tocolytic therapy: a meta-analysis and decision analysis. Obstet Gynecol 2009; 113:585.
  2. Sotiriadis A, Papatheodorou S, Kavvadias A, Makrydimas G. Transvaginal cervical length measurement for prediction of preterm birth in women with threatened preterm labor: a meta-analysis. Ultrasound Obstet Gynecol 2010; 35:54.
  3. Iams JD, Cebrik D, Lynch C, et al. The rate of cervical change and the phenotype of spontaneous preterm birth. Am J Obstet Gynecol 2011; 205:130.e1.
  4. Stafford IP, Garite TJ, Dildy GA, et al. A comparison of speculum and nonspeculum collection of cervicovaginal specimens for fetal fibronectin testing. Am J Obstet Gynecol 2008; 199:131.e1.
  5. Roman AS, Koklanaris N, Paidas MJ, et al. "Blind" vaginal fetal fibronectin as a predictor of spontaneous preterm delivery. Obstet Gynecol 2005; 105:285.
  6. Feinberg RF, Kliman HJ, Lockwood CJ. Is oncofetal fibronectin a trophoblast glue for human implantation? Am J Pathol 1991; 138:537.
  7. Berghella V, Saccone G. Fetal fibronectin testing for prevention of preterm birth in singleton pregnancies with threatened preterm labor: a systematic review and metaanalysis of randomized controlled trials. Am J Obstet Gynecol 2016; 215:431.
  8. Deshpande SN, van Asselt AD, Tomini F, et al. Rapid fetal fibronectin testing to predict preterm birth in women with symptoms of premature labour: a systematic review and cost analysis. Health Technol Assess 2013; 17:1.
  9. Sanchez-Ramos L, Delke I, Zamora J, Kaunitz AM. Fetal fibronectin as a short-term predictor of preterm birth in symptomatic patients: a meta-analysis. Obstet Gynecol 2009; 114:631.
  10. McKenna DS, Chung K, Iams JD. Effect of digital cervical examination on the expression of fetal fibronectin. J Reprod Med 1999; 44:796.
  11. McLaren JS, Hezelgrave NL, Ayubi H, et al. Prediction of spontaneous preterm birth using quantitative fetal fibronectin after recent sexual intercourse. Am J Obstet Gynecol 2015; 212:89.e1.
  12. Shimoya K, Hashimoto K, Shimizu T, et al. Cervical fluid oncofetal fibronectin as a predictor of early ectopic pregnancy. Is it affected by blood contamination? J Reprod Med 2002; 47:640.
  13. Ben-Haroush A, Poran E, Yogev Y, Glezerman M. Vaginal fetal fibronectin evaluation before and immediately after ultrasonographic vaginal cervical length measurements in symptomatic women at risk of preterm birth: a pilot study. J Matern Fetal Neonatal Med 2010; 23:854.
  14. http://www.ffntest.com/pdfs/rapid_ffn_product_insert_lettersize.pdf (Accessed on May 04, 2015).
  15. Abbott DS, Radford SK, Seed PT, et al. Evaluation of a quantitative fetal fibronectin test for spontaneous preterm birth in symptomatic women. Am J Obstet Gynecol 2013; 208:122.e1.
  16. Kuhrt K, Unwin C, Hezelgrave N, et al. Endocervical and high vaginal quantitative fetal fibronectin in predicting preterm birth. J Matern Fetal Neonatal Med 2014; 27:1576.
  17. Kuhrt K, Hezelgrave N, Foster C, et al. Development and validation of a tool incorporating quantitative fetal fibronectin to predict spontaneous preterm birth in symptomatic women. Ultrasound Obstet Gynecol 2016; 47:210.
  18. Bruijn MM, Kamphuis EI, Hoesli IM, et al. The predictive value of quantitative fibronectin testing in combination with cervical length measurement in symptomatic women. Am J Obstet Gynecol 2016; 215:793.e1.
  19. Kuhrt K, Smout E, Hezelgrave N, et al. Development and validation of a tool incorporating cervical length and quantitative fetal fibronectin to predict spontaneous preterm birth in asymptomatic high-risk women. Ultrasound Obstet Gynecol 2016; 47:104.
  20. www.QUiPP.org.
  21. Ehsanipoor RM, Swank ML, Jwa SC, et al. Placental α-Microglobulin-1 in Vaginal Secretions of Women with Evidence of Preterm Labor. Am J Perinatol 2016; 33:208.
  22. Nikolova T, Bayev O, Nikolova N, Di Renzo GC. Comparison of a novel test for placental alpha microglobulin-1 with fetal fibronectin and cervical length measurement for the prediction of imminent spontaneous preterm delivery in patients with threatened preterm labor. J Perinat Med 2015; 43:395.
  23. Ting HS, Chin PS, Yeo GS, Kwek K. Comparison of bedside test kits for prediction of preterm delivery: phosphorylated insulin-like growth factor binding protein-1 (pIGFBP-1) test and fetal fibronectin test. Ann Acad Med Singapore 2007; 36:399.
  24. Iams JD. Prediction and early detection of preterm labor. Obstet Gynecol 2003; 101:402.
  25. Chao TT, Bloom SL, Mitchell JS, et al. The diagnosis and natural history of false preterm labor. Obstet Gynecol 2011; 118:1301.
  26. Tsoi E, Fuchs IB, Rane S, et al. Sonographic measurement of cervical length in threatened preterm labor in singleton pregnancies with intact membranes. Ultrasound Obstet Gynecol 2005; 25:353.
  27. Ness A, Visintine J, Ricci E, Berghella V. Does knowledge of cervical length and fetal fibronectin affect management of women with threatened preterm labor? A randomized trial. Am J Obstet Gynecol 2007; 197:426.e1.
  28. Murakawa H, Utumi T, Hasegawa I, et al. Evaluation of threatened preterm delivery by transvaginal ultrasonographic measurement of cervical length. Obstet Gynecol 1993; 82:829.
  29. Tsoi E, Akmal S, Rane S, et al. Ultrasound assessment of cervical length in threatened preterm labor. Ultrasound Obstet Gynecol 2003; 21:552.
  30. Melamed N, Hiersch L, Domniz N, et al. Predictive value of cervical length in women with threatened preterm labor. Obstet Gynecol 2013; 122:1279.
  31. van Baaren GJ, Vis JY, Wilms FF, et al. Predictive value of cervical length measurement and fibronectin testing in threatened preterm labor. Obstet Gynecol 2014; 123:1185.
  32. Schmitz T, Maillard F, Bessard-Bacquaert S, et al. Selective use of fetal fibronectin detection after cervical length measurement to predict spontaneous preterm delivery in women with preterm labor. Am J Obstet Gynecol 2006; 194:138.
  33. Audibert F, Fortin S, Delvin E, et al. Contingent use of fetal fibronectin testing and cervical length measurement in women with preterm labour. J Obstet Gynaecol Can 2010; 32:307.
  34. Foster C, Shennan AH. Fetal fibronectin as a biomarker of preterm labor: a review of the literature and advances in its clinical use. Biomark Med 2014; 8:471.
  35. Committee on Practice Bulletins—Obstetrics, The American College of Obstetricians and Gynecologists. Practice bulletin no. 130: prediction and prevention of preterm birth. Obstet Gynecol 2012; 120:964.
  36. Society for Maternal-Fetal Medicine (SMFM). Electronic address: pubs@smfm.org, McIntosh J, Feltovich H, et al. The role of routine cervical length screening in selected high- and low-risk women for preterm birth prevention. Am J Obstet Gynecol 2016; 215:B2.
  37. Gomez R, Romero R, Medina L, et al. Cervicovaginal fibronectin improves the prediction of preterm delivery based on sonographic cervical length in patients with preterm uterine contractions and intact membranes. Am J Obstet Gynecol 2005; 192:350.
  38. Hincz P, Wilczynski J, Kozarzewski M, Szaflik K. Two-step test: the combined use of fetal fibronectin and sonographic examination of the uterine cervix for prediction of preterm delivery in symptomatic patients. Acta Obstet Gynecol Scand 2002; 81:58.
  39. Fox NS, Saltzman DH, Fishman A, et al. Gestational age at cervical length and fetal fibronectin assessment and the incidence of spontaneous preterm birth in twins. J Ultrasound Med 2015; 34:977.
  40. Melamed N, Hiersch L, Gabbay-Benziv R, et al. Predictive value of cervical length in women with twin pregnancy presenting with threatened preterm labor. Ultrasound Obstet Gynecol 2015; 46:73.
  41. American College of Obstetricians and Gynecologists’ Committee on Practice Bulletins—Obstetrics. Practice Bulletin No. 171: Management of Preterm Labor. Obstet Gynecol 2016; 128:e155.
  42. American College of Obstetricians and Gynecologists. ACOG Practice Bulletin No. 120: Use of prophylactic antibiotics in labor and delivery. Obstet Gynecol 2011; 117:1472.
  43. Hackney DN, Olson-Chen C, Thornburg LL. What do we know about the natural outcomes of preterm labour? A systematic review and meta-analysis of women without tocolysis in preterm labour. Paediatr Perinat Epidemiol 2013; 27:452.
  44. Paules C, Pueyo V, Martí E, et al. Threatened preterm labor is a risk factor for impaired cognitive development in early childhood. Am J Obstet Gynecol 2016.
  45. Romero R, Erez O, Maymon E, Pacora P. Is an episode of suspected preterm labor that subsequently leads to a term delivery benign? Am J Obstet Gynecol 2017; 157:89.
  46. Campbell MK, Cartier S, Xie B, et al. Determinants of small for gestational age birth at term. Paediatr Perinat Epidemiol 2012; 26:525.
  47. Spong CY. Defining "term" pregnancy: recommendations from the Defining "Term" Pregnancy Workgroup. JAMA 2013; 309:2445.
  48. ACOG Committee Opinion No 579: Definition of term pregnancy. Obstet Gynecol 2013; 122:1139.
  49. World Health Organization (WHO) fact sheet on preterm birth http://www.who.int/mediacentre/factsheets/fs363/en/ (Accessed on April 22, 2015).
  50. http://www.cdc.gov/mmwr/preview/mmwrhtml/su6203a22.htm (Accessed on June 18, 2015).
  51. World Health Organization. Guidelines on optimal feeding of low birth-weight infants in low-and middle-income countries. 2011.
  52. WHO, March of Dimes, Partnership for Maternal, Newborn & Child Health, Save the Children. Born too soon: the global action report on preterm birth. www.who.int/maternal_child_adolescent/documents/born_too_soon/en/ (Accessed on May 04, 2012).
  53. Blencowe H, Cousens S, Oestergaard MZ, et al. National, regional, and worldwide estimates of preterm birth rates in the year 2010 with time trends since 1990 for selected countries: a systematic analysis and implications. Lancet 2012; 379:2162.
  54. Martin JA, Hamilton BE, Osterman MJ, et al. Births: final data for 2013. Natl Vital Stat Rep 2015; 64:1.
  55. www.cdc.gov/nchs/vitalstats.htm (Accessed on April 19, 2012).
  56. Lawn JE, Gravett MG, Nunes TM, et al. Global report on preterm birth and stillbirth (1 of 7): definitions, description of the burden and opportunities to improve data. BMC Pregnancy Childbirth 2010; 10 Suppl 1:S1.
  57. Delorme P, Goffinet F, Ancel PY, et al. Cause of Preterm Birth as a Prognostic Factor for Mortality. Obstet Gynecol 2016; 127:40.
  58. Mwaniki MK, Atieno M, Lawn JE, Newton CR. Long-term neurodevelopmental outcomes after intrauterine and neonatal insults: a systematic review. Lancet 2012; 379:445.
  59. Heida KY, Velthuis BK, Oudijk MA, et al. Cardiovascular disease risk in women with a history of spontaneous preterm delivery: A systematic review and meta-analysis. Eur J Prev Cardiol 2016; 23:253.
  60. Chang HH, Larson J, Blencowe H, et al. Preventing preterm births: analysis of trends and potential reductions with interventions in 39 countries with very high human development index. Lancet 2013; 381:223.
  61. Shapiro-Mendoza CK, Barfield WD, Henderson Z, et al. CDC Grand Rounds: Public Health Strategies to Prevent Preterm Birth. MMWR Morb Mortal Wkly Rep 2016; 65:826.