Epidemiology of late preterm and early term births – An international perspective

  • Marie Delnord
    Inserm UMR 1153, Obstetrical, Perinatal and Pediatric Epidemiology Research Team (Epopé), Center for Epidemiology and Statistics Sorbonne Paris Cité, DHU Risks in Pregnancy, Paris Descartes University, Paris, France
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  • Jennifer Zeitlin
    Corresponding author. INSERM U1153, 53 Avenue de l'observatoire, 75014, Paris, France.
    Inserm UMR 1153, Obstetrical, Perinatal and Pediatric Epidemiology Research Team (Epopé), Center for Epidemiology and Statistics Sorbonne Paris Cité, DHU Risks in Pregnancy, Paris Descartes University, Paris, France
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Published:October 08, 2018DOI:https://doi.org/10.1016/j.siny.2018.09.001


      Late preterm (34–36 weeks of gestational age (GA)), and early term (37–38 weeks GA) birth rates among singleton live births vary from 3% to 6% and from 15% to 31%, respectively, across countries, although data from low- and middle-income countries are sparse. Countries with high preterm birth rates are more likely to have high early term birth rates; many risk factors are shared, including pregnancy complications (hypertension, diabetes), medical practices (provider-initiated delivery, assisted reproduction), maternal socio-demographic and lifestyle characteristics and environmental factors. Exceptions include nulliparity and inflammation which increase risks for preterm, but not early term birth. Birth before 39 weeks GA is associated with adverse child health outcomes across a wide range of settings. International rate variations suggest that reductions in early delivery are achievable; implementation of best practice guidelines for obstetrical interventions and public health policies targeting population risk factors could contribute to prevention of both late preterm and early term births.


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        • Blencowe H.
        • Cousens S.
        • Oestergaard M.Z.
        • 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 (*): 2162-2172
        • Saigal S.
        • Doyle L.W.
        An overview of mortality and sequelae of preterm birth from infancy to adulthood.
        Lancet. 2008; 371: 261-269
        • Raju T.
        The “late preterm” birth – ten years later.
        Pediatrics. 2017; 139
        • Brown H.K.
        • Speechley K.N.
        • Macnab J.
        • Natale R.
        • Campbell M.K.
        Neonatal morbidity associated with late preterm and early term birth: the roles of gestational age and biological determinants of preterm birth.
        Int J Epidemiol. 2014; 43: 802-814
        • Yang S.
        • Platt R.W.
        • Kramer M.S.
        Variation in child cognitive ability by week of gestation among healthy term births.
        Am J Epidemiol. 2010; 171: 399-406
        • Shapiro-Mendoza C.K.
        • Lackritz E.M.
        Epidemiology of late and moderate preterm birth.
        Semin Fetal Neonatal Med. 2012; 17: 120-125
        • Blencowe H.
        • Lee A.C.
        • Cousens S.
        • et al.
        Preterm birth-associated neurodevelopmental impairment estimates at regional and global levels for 2010.
        Pediatr Res. 2013; 74: 17-34
        • World Health Organization
        International classification of diseases.
        • World Health Organization
        Preterm birth.
        • Barros F.C.
        • Papageorghiou A.T.
        • Victora C.G.
        • et al.
        The distribution of clinical phenotypes of preterm birth syndrome: implications for prevention.
        JAMA Pediatr. 2015; 169: 220-229
        • Goldenberg R.L.
        • Gravett M.G.
        • Iams J.
        • et al.
        The preterm birth syndrome: issues to consider in creating a classification system.
        Am J Obstet Gynecol. 2012; 206: 113-118
        • Chang H.H.
        • 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 (*): 223-234
        • Spong C.Y.
        • Mercer B.M.
        • D'Alton M.
        • Kilpatrick S.
        • Blackwell S.
        • Saade G.
        Timing of indicated late-preterm and early-term birth.
        Obstet Gynecol. 2011; 118 (*): 323-333
        • Raju T.N.
        • Higgins R.D.
        • Stark A.R.
        • Leveno K.J.
        Optimizing care and outcome for late-preterm (near-term) infants: a summary of the workshop sponsored by the National Institute of Child Health and Human Development.
        Pediatrics. 2006; 118: 1207-1214
        • Spong C.Y.
        Defining “term” pregnancy: recommendations from the defining “term” pregnancy workgroup.
        J Am Med Assoc. 2013; 309: 2445-2446
        • Morisaki N.
        • Ganchimeg T.
        • Vogel J.P.
        • et al.
        Impact of stillbirths on international comparisons of preterm birth rates: a secondary analysis of the who multi-country survey of maternal and newborn health.
        Br J Obstet Gynaecol. 2017; 124: 1346-1354
        • Delnord M.
        • Hindori-Mohangoo A.D.
        • Smith L.K.
        • et al.
        Variations in very preterm birth rates in 30 high-income countries: are valid international comparisons possible using routine data?.
        Br J Obstet Gynaecol. 2017; 124: 785-794
        • Villar J.
        • Cheikh Ismail L.
        • Victora C.G.
        • et al.
        International standards for newborn weight, length, and head circumference by gestational age and sex: the newborn cross-sectional study of the Intergrowth-21st project.
        Lancet. 2014; 384: 857-868
        • Vogel J.P.
        • Chawanpaiboon S.
        • Watananirun K.
        • et al.
        Global, regional and national levels and trends of preterm birth rates for 1990 to 2014: protocol for development of World Health Organization estimates.
        Reprod Health. 2016; 13: 76
        • Morisaki N.
        • Zhang X.
        • Ganchimeg T.
        • et al.
        Provider-initiated delivery, late preterm birth and perinatal mortality: a secondary analysis of the WHO Multicountry Survey on Maternal and Newborn Health.
        BMJ Glob Health. 2017; 2e000204
        • Delnord M.
        • Mortensen L.
        • Hindori-Mohangoo A.D.
        • et al.
        International variations in the gestational age distribution of births: an ecological study in 34 high-income countries.
        Eur J Publ Health. 2018; 28 (*): 303-309
        • Zeitlin J.
        • Szamotulska K.
        • Drewniak N.
        • et al.
        Preterm birth time trends in Europe: a study of 19 countries.
        Br J Obstet Gynaecol. 2013; 120 (*): 1356-1365
        • Richards J.L.
        • Kramer M.S.
        • Deb-Rinker P.
        • et al.
        Temporal trends in late preterm and early term birth rates in 6 high-income countries in North America and Europe and association with clinician-initiated obstetric interventions.
        J Am Med Assoc. 2016; 316 (*): 410-419
        • Joseph K.S.
        • Liu S.
        • Rouleau J.
        • et al.
        Influence of definition based versus pragmatic birth registration on international comparisons of perinatal and infant mortality: population based retrospective study.
        BMJ. 2012; 344: e746
        • Blondel B.
        • Morin I.
        • Platt R.W.
        • Kramer M.S.
        • Usher R.
        • Breart G.
        Algorithms for combining menstrual and ultrasound estimates of gestational age: consequences for rates of preterm and postterm birth.
        Br J Obstet Gynaecol. 2002; 109: 718-720
        • Hall E.S.
        • Folger A.T.
        • Kelly E.A.
        • Kamath-Rayne B.D.
        Evaluation of gestational age estimate method on the calculation of preterm birth rates.
        Matern Child Health J. 2014; 18: 755-762
        • Yang H.
        • Kramer M.S.
        • Platt R.W.
        • et al.
        How does early ultrasound scan estimation of gestational age lead to higher rates of preterm birth?.
        Am J Obstet Gynecol. 2002; 186: 433-437
        • Martin J.A.
        • Osterman M.J.
        • Kirmeyer S.E.
        • Gregory E.C.
        Measuring gestational age in vital statistics data: transitioning to the obstetric estimate.
        Natl Vital Stat Rep. 2015; 64: 1-20
        • Ioannou C.
        • Talbot K.
        • Ohuma E.
        • et al.
        Systematic review of methodology used in ultrasound studies aimed at creating charts of fetal size.
        Br J Obstet Gynaecol. 2012; 119: 1425-1439
        • Jukic A.M.
        The impact of systematic errors on gestational age estimation.
        Br J Obstet Gynaecol. 2015; 122: 842
        • Heino A.
        • Gissler M.
        • Hindori-Mohangoo A.D.
        • et al.
        Variations in multiple birth rates and impact on perinatal outcomes in Europe.
        PLoS One. 2016; 11e0149252
        • Delnord M.
        • Blondel B.
        • Zeitlin J.
        What contributes to disparities in the preterm birth rate in European countries?.
        Curr Opin Obstet Gynecol. 2015; 27 (*): 133-142
        • Leal M.D.C.
        • Esteves-Pereira A.P.
        • Nakamura-Pereira M.
        • et al.
        Burden of early-term birth on adverse infant outcomes: a population-based cohort study in Brazil.
        BMJ Open. 2017; 7e017789
        • Han Y.
        • Mao L.J.
        • Ge X.
        • et al.
        Impact of maternal thyroid autoantibodies positivity on the risk of early term birth: Ma’anshan birth cohort study.
        Endocrine. 2018; 60: 329-338
        • VanderWeele T.J.
        • Lantos J.D.
        • Lauderdale D.S.
        Rising preterm birth rates, 1989–2004: changing demographics or changing obstetric practice?.
        Soc Sci Med. 2012; 74: 196-201
        • Gyamfi-Bannerman C.
        • Ananth C.V.
        Trends in spontaneous and indicated preterm delivery among singleton gestations in the United States, 2005–2012.
        Obstet Gynecol. 2014; 124: 1069-1074
        • Ananth C.V.
        • Goldenberg R.L.
        • Friedman A.M.
        • Vintzileos A.M.
        Association of temporal changes in gestational age with perinatal mortality in the United States, 2007–2015.
        JAMA Pediatr. 2018; 172 (*): 627-634https://doi.org/10.1001/jamapediatrics.2018.0249
        • Goldenberg R.L.
        • Culhane J.F.
        • Iams J.D.
        • Romero R.
        Epidemiology and causes of preterm birth.
        Lancet. 2008; 371: 75-84
        • Brown H.K.
        • Speechley K.N.
        • Macnab J.
        • Natale R.
        • Campbell M.K.
        Biological determinants of spontaneous late preterm and early term birth: a retrospective cohort study.
        Br J Obstet Gynaecol. 2015; 122 (*): 491-499
        • Strauss 3rd, J.F.
        • Romero R.
        • Gomez-Lopez N.
        • et al.
        Spontaneous preterm birth: advances toward the discovery of genetic predisposition.
        Am J Obstet Gynecol. 2018; 218: 294-314 e2
        • Ferrero D.M.
        • Larson J.
        • Jacobsson B.
        • et al.
        Cross-country individual participant analysis of 4.1 million singleton births in 5 countries with very high human development index confirms known associations but provides no biologic explanation for 2/3 of all preterm births.
        PLoS One. 2016; 11e0162506
        • Brown H.K.
        • Speechley K.N.
        • Macnab J.
        • Natale R.
        • Campbell M.K.
        Maternal, fetal, and placental conditions associated with medically indicated late preterm and early term delivery: a retrospective study.
        Br J Obstet Gynaecol. 2016; 123 (*): 763-770
        • Delnord M.
        • Blondel B.
        • Prunet C.
        • Zeitlin J.
        Are risk factors for preterm and early-term live singleton birth the same? A population-based study in France.
        BMJ Open. 2018; 8e018745
        • Blencowe H.
        • Cousens S.
        • Chou D.
        • et al.
        Born too soon: the global epidemiology of 15 million preterm births.
        Reprod Health. 2013; 10: S2
        • Sorbye I.K.
        • Wanigaratne S.
        • Urquia M.L.
        Variations in gestational length and preterm delivery by race, ethnicity and migration.
        Best Pract Res Clin Obstet Gynaecol. 2016; 32: 60-68
        • McKinnon B.
        • Yang S.
        • Kramer M.S.
        • Bushnik T.
        • Sheppard A.J.
        • Kaufman J.S.
        Comparison of black-white disparities in preterm birth between Canada and the United States.
        Can Med Assoc J. 2016; 188: E19-E26
        • Ruiz M.
        • Goldblatt P.
        • Morrison J.
        • et al.
        Mother's education and the risk of preterm and small for gestational age birth: a drivers meta-analysis of 12 European cohorts.
        J Epidemiol Community Health. 2015; 69: 826-833
        • Wallace M.E.
        • Mendola P.
        • Chen Z.
        • Hwang B.S.
        • Grantz K.L.
        Preterm birth in the context of increasing income inequality.
        Matern Child Health J. 2016; 20: 164-171
        • Savitz D.A.
        • Harmon Q.
        • Siega-Riz A.M.
        • Herring A.H.
        • Dole N.
        • Thorp Jr., J.M.
        Behavioral influences on preterm birth: integrated analysis of the Pregnancy, Infection, and Nutrition Study.
        Matern Child Health J. 2012; 16: 1151-1163
        • Cnattingius S.
        • Villamor E.
        • Johansson S.
        • et al.
        Maternal obesity and risk of preterm delivery.
        J Am Med Assoc. 2013; 309: 2362-2370
        • Englund-Ogge L.
        • Brantsaeter A.L.
        • Sengpiel V.
        • et al.
        Maternal dietary patterns and preterm delivery: results from large prospective cohort study.
        BMJ. 2014; 348: g1446
        • Rogne T.
        • Tielemans M.J.
        • Chong M.F.
        • et al.
        Associations of maternal vitamin b12 concentration in pregnancy with the risks of preterm birth and low birth weight: a systematic review and meta-analysis of individual participant data.
        Am J Epidemiol. 2017; 185: 212-223
        • Aune D.
        • Schlesinger S.
        • Henriksen T.
        • Saugstad O.D.
        • Tonstad S.
        Physical activity and the risk of preterm birth: a systematic review and meta-analysis of epidemiological studies.
        Br J Obstet Gynaecol. 2017; 124: 1816-1826
        • Kramer M.R.
        • Hogue C.J.
        • Dunlop A.L.
        • Menon R.
        Preconceptional stress and racial disparities in preterm birth: an overview.
        Acta Obstet Gynecol Scand. 2011; 90: 1307-1316
        • Agbla F.
        • Ergin A.
        • Boris N.W.
        Occupational working conditions as risk factors for preterm birth in Benin, West Africa.
        Rev Epidemiol Sante Publique. 2006; 54: 157-165
        • Ferguson K.K.
        • O'Neill M.S.
        • Meeker J.D.
        Environmental contaminant exposures and preterm birth: a comprehensive review.
        J Toxicol Environ Health B Crit Rev. 2013; 16: 69-113
        • Vollrath M.E.
        • Sengpiel V.
        • Landolt M.A.
        • Jacobsson B.
        • Latal B.
        Is maternal trait anxiety a risk factor for late preterm and early term deliveries?.
        BMC Pregnancy Childbirth. 2016; 16: 286
        • Been J.V.
        • Nurmatov U.B.
        • Cox B.
        • Nawrot T.S.
        • van Schayck C.P.
        • Sheikh A.
        Effect of smoke-free legislation on perinatal and child health: a systematic review and meta-analysis.
        Lancet. 2014; 383: 1549-1560
        • Elkin E.R.
        • O'Neill M.S.
        Trends in environmental tobacco smoke (ETS) exposure and preterm birth: use of smoking bans and direct ets exposure assessments in study designs.
        Chem Res Toxicol. 2017; 30: 1376-1383
        • Vicedo-Cabrera A.M.
        • Schindler C.
        • Radovanovic D.
        • et al.
        Benefits of smoking bans on preterm and early-term births: a natural experimental design in Switzerland.
        Tobac Contr. 2016; 25: e135-e141
        • Li X.
        • Huang S.
        • Jiao A.
        • et al.
        Association between ambient fine particulate matter and preterm birth or term low birth weight: an updated systematic review and meta-analysis.
        Environ Pollut. 2017; 227: 596-605
        • Hu J.
        • Xia W.
        • Pan X.
        • et al.
        Association of adverse birth outcomes with prenatal exposure to vanadium: a population-based cohort study.
        Lancet Planetary Health. 2017; 1 (e230–e41)
        • American College of Obstetricians and Gynecologists
        ACOG Committee Opinion no. 560: medically indicated late-preterm and early-term deliveries.
        Obstet Gynecol. 2013; 121: 908-910
        • Delnord M.
        • Blondel B.
        • Drewniak N.
        • et al.
        Varying gestational age patterns in cesarean delivery: an international comparison.
        BMC Pregnancy Childbirth. 2014; 14: 321
        • Dunietz G.L.
        • Holzman C.
        • McKane P.
        • et al.
        Assisted reproductive technology and the risk of preterm birth among primiparas.
        Fertil Steril. 2015; 103 (e1): 974-979
        • Kushnir V.A.
        • Barad D.H.
        • Albertini D.F.
        • Darmon S.K.
        • Gleicher N.
        Systematic review of worldwide trends in assisted reproductive technology 2004–2013.
        Reprod Biol Endocrinol. 2017; 15: 6
        • Ananth C.V.
        • Friedman A.M.
        • Gyamfi-Bannerman C.
        Epidemiology of moderate preterm, late preterm and early term delivery.
        Clin Perinatol. 2013; 40: 601-610
        • Matthews T.J.
        • MacDorman M.F.
        • Thoma M.E.
        Infant mortality statistics from the 2013 Period Linked birth/infant death data set.
        Natl Vital Stat Rep. 2015; 64: 1-30
        • Odibo I.N.
        • Bird T.M.
        • McKelvey S.S.
        • Sandlin A.
        • Lowery C.
        • Magann E.F.
        Childhood respiratory morbidity after late preterm and early term delivery: a study of Medicaid patients in South Carolina.
        Paediatr Perinat Epidemiol. 2016; 30: 67-75
        • Crump C.
        • Sundquist K.
        • Sundquist J.
        • Winkleby M.A.
        Gestational age at birth and mortality in young adulthood.
        J Am Med Assoc. 2011; 306: 1233-1240
        • Raju T.N.K.
        • Buist A.S.
        • Blaisdell C.J.
        • Moxey-Mims M.
        • Saigal S.
        Adults born preterm: a review of general health and system-specific outcomes.
        Acta Paediatr. 2017; 106: 1409-1437
        • Barros J.G.
        • Clode N.
        • Graca L.M.
        Prevalence of late preterm and early term birth in Portugal.
        Acta Med Port. 2016; 29: 249-253
        • Helle E.
        • Andersson S.
        • Hakkinen U.
        • Jarvelin J.
        • Eskelinen J.
        • Kajantie E.
        Morbidity and health care costs after early term birth.
        Paediatr Perinat Epidemiol. 2016; 30: 533-540
        • Stene-Larsen K.
        • Lang A.M.
        • Landolt M.A.
        • Latal B.
        • Vollrath M.E.
        Emotional and behavioral problems in late preterm and early term births: outcomes at child age 36 months.
        BMC Pediatr. 2016; 16: 196
        • National Institute of Child Health and Human Development
        • National Institute for Healthcare Management
        Born too early: improving maternal and child health by reducing early elective deliveries.