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Diagnosis of preterm labor

Charles J Lockwood, MD, MHCM
Section Editor
Vincenzo Berghella, 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 approximately 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 at least 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

Inflammation and infection

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Literature review current through: Nov 2017. | This topic last updated: Nov 22, 2017.
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  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. Committee on Practice Bulletins—Obstetrics and the American Institute of Ultrasound in Medicine. Practice Bulletin No. 175: Ultrasound in Pregnancy. Obstet Gynecol 2016; 128:e241.
  5. 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.
  6. Roman AS, Koklanaris N, Paidas MJ, et al. "Blind" vaginal fetal fibronectin as a predictor of spontaneous preterm delivery. Obstet Gynecol 2005; 105:285.
  7. Berghella V, Palacio M, Ness A, et al. Cervical length screening for prevention of preterm birth in singleton pregnancy with threatened preterm labor: systematic review and meta-analysis of randomized controlled trials using individual patient-level data. Ultrasound Obstet Gynecol 2017; 49:322.
  8. Feinberg RF, Kliman HJ, Lockwood CJ. Is oncofetal fibronectin a trophoblast glue for human implantation? Am J Pathol 1991; 138:537.
  9. 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.
  10. 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.
  11. 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.
  12. McKenna DS, Chung K, Iams JD. Effect of digital cervical examination on the expression of fetal fibronectin. J Reprod Med 1999; 44:796.
  13. 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.
  14. 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.
  15. 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.
  16. http://www.ffntest.com/pdfs/rapid_ffn_product_insert_lettersize.pdf (Accessed on May 04, 2015).
  17. 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.
  18. 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.
  19. 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.
  20. 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.
  21. 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.
  22. www.QUiPP.org.
  23. Watson HA, Carter J, Seed PT, et al. The QUiPP App: a safe alternative to a treat-all strategy for threatened preterm labor. Ultrasound Obstet Gynecol 2017; 50:342.
  24. 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.
  25. 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.
  26. Wing DA, Haeri S, Silber AC, et al. Placental Alpha Microglobulin-1 Compared With Fetal Fibronectin to Predict Preterm Delivery in Symptomatic Women. Obstet Gynecol 2017; 130:1183.
  27. 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.
  28. Iams JD. Prediction and early detection of preterm labor. Obstet Gynecol 2003; 101:402.
  29. Chao TT, Bloom SL, Mitchell JS, et al. The diagnosis and natural history of false preterm labor. Obstet Gynecol 2011; 118:1301.
  30. 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.
  31. 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.
  32. 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.
  33. Tsoi E, Akmal S, Rane S, et al. Ultrasound assessment of cervical length in threatened preterm labor. Ultrasound Obstet Gynecol 2003; 21:552.
  34. Melamed N, Hiersch L, Domniz N, et al. Predictive value of cervical length in women with threatened preterm labor. Obstet Gynecol 2013; 122:1279.
  35. 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.
  36. 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.
  37. 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.
  38. 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.
  39. 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.
  40. 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.
  41. 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.
  42. 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.
  43. 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.
  44. 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.
  45. American College of Obstetricians and Gynecologists’ Committee on Practice Bulletins—Obstetrics. Practice Bulletin No. 171: Management of Preterm Labor. Obstet Gynecol 2016; 128:e155.
  46. Zephyrin LC, Hong KN, Wapner RJ, et al. Gestational age-specific risks vs benefits of multicourse antenatal corticosteroids for preterm labor. Am J Obstet Gynecol 2013; 209:330.e1.
  47. American College of Obstetricians and Gynecologists. ACOG Practice Bulletin No. 120: Use of prophylactic antibiotics in labor and delivery. Obstet Gynecol 2011; 117:1472.
  48. 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.
  49. 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 2017; 216:157.e1.
  50. 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.
  51. Campbell MK, Cartier S, Xie B, et al. Determinants of small for gestational age birth at term. Paediatr Perinat Epidemiol 2012; 26:525.