Overview of preterm labor and birth
- Charles J Lockwood, MD, MHCM
Charles J Lockwood, MD, MHCM
- Section Editor — Obstetrics
- Senior Vice President, USF Health
- Dean, Morsani College of Medicine
- Professor, Obstetrics and Gynecology
- University of South Florida
Preterm birth refers to a delivery that occurs before 370/7ths weeks of gestation. It may or may not be preceded by preterm labor. Although term pregnancy has been defined as 370/7ths to 416/7ths weeks of gestation, the period 370/7ths to 386/7ths weeks should be considered ‘early term’ because neonates born in this gestational age range have higher neonatal morbidity and mortality than infants born at ‘full term’ from 390/7ths to 406/7ths weeks [1,2].
Classification — Subtypes of preterm birth are variably defined.
By gestational age :
●Moderate preterm: 32 to <37 weeks
●Late preterm: 340/7ths to 366/7ths weeks
- Spong CY. Defining "term" pregnancy: recommendations from the Defining "Term" Pregnancy Workgroup. JAMA 2013; 309:2445.
- ACOG Committee Opinion No 579: Definition of term pregnancy. Obstet Gynecol 2013; 122:1139.
- 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).
- WHO Statistical Information System (WHOSIS). Low birthweight newborns. www.who.int/whosis/indicators/compendium/2008/2bwn/en/index.html (Accessed on April 16, 2012).
- Villar J, Papageorghiou AT, Knight HE, et al. The preterm birth syndrome: a prototype phenotypic classification. Am J Obstet Gynecol 2012; 206:119.
- 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.
- Mwaniki MK, Atieno M, Lawn JE, Newton CR. Long-term neurodevelopmental outcomes after intrauterine and neonatal insults: a systematic review. Lancet 2012; 379:445.
- Martin JA, Hamilton BE, Ventura SJ, et al. Births: final data for 2011. Natl Vital Stat Rep 2013; 62:1.
- 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.
- Zakar T, Mesiano S. How does progesterone relax the uterus in pregnancy? N Engl J Med 2011; 364:972.
- McMaster-Fay RA. Failure of physiologic transformation of the spiral arteries of the uteroplacental circulation in patients with preterm labor and intact membranes. Am J Obstet Gynecol 2004; 191:1837.
- Romero R, Kusanovic JP, Chaiworapongsa T, Hassan SS. Placental bed disorders in preterm labor, preterm PROM, spontaneous abortion and abruptio placentae. Best Pract Res Clin Obstet Gynaecol 2011; 25:313.
- www.cdc.gov/nchs/vitalstats.htm (Accessed on April 19, 2012).
- 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.
- Iams JD. Prediction and early detection of preterm labor. Obstet Gynecol 2003; 101:402.
- Chao TT, Bloom SL, Mitchell JS, et al. The diagnosis and natural history of false preterm labor. Obstet Gynecol 2011; 118:1301.
- King JF, Grant A, Keirse MJ, Chalmers I. Beta-mimetics in preterm labour: an overview of the randomized controlled trials. Br J Obstet Gynaecol 1988; 95:211.
- 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.
- Gazmararian JA, Petersen R, Jamieson DJ, et al. Hospitalizations during pregnancy among managed care enrollees. Obstet Gynecol 2002; 100:94.
- Scott CL, Chavez GF, Atrash HK, et al. Hospitalizations for severe complications of pregnancy, 1987-1992. Obstet Gynecol 1997; 90:225.
- McPheeters ML, Miller WC, Hartmann KE, et al. The epidemiology of threatened preterm labor: a prospective cohort study. Am J Obstet Gynecol 2005; 192:1325.
- 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.
- 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.
- 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.
- Tsoi E, Akmal S, Rane S, et al. Ultrasound assessment of cervical length in threatened preterm labor. Ultrasound Obstet Gynecol 2003; 21:552.
- Fuchs I, Tsoi E, Henrich W, et al. Sonographic measurement of cervical length in twin pregnancies in threatened preterm labor. Ultrasound Obstet Gynecol 2004; 23:42.
- Melamed N, Hiersch L, Domniz N, et al. Predictive value of cervical length in women with threatened preterm labor. Obstet Gynecol 2013; 122:1279.
- van Baaren GJ, Vis JY, Grobman WA, et al. Cost-effectiveness analysis of cervical length measurement and fibronectin testing in women with threatened preterm labor. Am J Obstet Gynecol 2013; 209:436.e1.
- American College of Obstetricians and Gynecologists, Committee on Practice Bulletins—Obstetrics. ACOG practice bulletin no. 127: Management of preterm labor. Obstet Gynecol 2012; 119:1308.
- American College of Obstetricians and Gynecologists. ACOG Practice Bulletin No. 120: Use of prophylactic antibiotics in labor and delivery. Obstet Gynecol 2011; 117:1472.
- 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.
- PRETERM BIRTH
- Pathogenesis of spontaneous preterm birth
- Epidemiology and risk factors for spontaneous preterm birth
- PRETERM LABOR
- Clinical manifestations
- Approach to the patient with suspected preterm labor
- - Initial evaluation
- - Triage based upon cervical length
- Cervical length >30 mm
- Cervical length 20 to 30 mm
- Cervical length <20 mm
- INFORMATION FOR PATIENTS
- SUMMARY AND RECOMMENDATIONS