title: The NICHD Consecutive Pregnancies Study: recurrent preterm delivery by subtype.
abstract: OBJECTIVE
  Attention for recurrent preterm delivery has primarily focused on spontaneous subtypes with less known about indicated preterm delivery.
  
  
  METHODS
  In a retrospective cohort of consecutive pregnancies among 51,086 women in Utah (2002-2010), binary relative risk regression was performed to examine the risk of preterm delivery (PTD; <37 weeks) in the second observed delivery by PTD in the first, adjusting for maternal age, race/ethnicity, prepregnancy body mass index, insurance, smoking, alcohol and/or drug use, and chronic disease. Analyses were also performed stratified by prior preterm delivery subtype: spontaneous, indicated, or no recorded indication.
  
  
  RESULTS
  There were 3836 women who delivered preterm in the first observed pregnancy (7.6%), of which 1160 repeated in the second (30.7%). Rate of recurrent PTD was 31.6% for prior spontaneous, 23.0% for prior indicated delivery, and 27.4% for prior elective delivery. Prior spontaneous PTD was associated with a relative risk (RR) of 5.64 (95% confidence interval [CI], 5.27-6.05) of subsequent spontaneous and RR of 1.61 (95% CI, 0.98-2.67) of subsequent indicated PTD. Prior indicated PTD was associated with an RR of 9.10 (95% CI, 4.68-17.71) of subsequent indicated and RR of 2.70 (95% CI, 2.00-3.65) of subsequent spontaneous PTD.
  
  
  CONCLUSIONS
  Prior indicated PTD was strongly associated with subsequent indicated PTD and with increased risk for subsequent spontaneous PTD. Spontaneous PTD had the highest rate of recurrence. Some common pathways for different etiologies of preterm delivery are likely, and indicated PTD merits additional attention for recurrence risk.
authors.affiliation: Epidemiology Branch, Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Rockville, MD.
authors.forename: S Katherine
authors.initials: SK
authors.lastname: Laughon
authors.affiliation: Biostatistics and Bioinformatics Branch, Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Rockville, MD.
authors.forename: Paul S
authors.initials: PS
authors.lastname: Albert
authors.affiliation: Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Rockville, MD.
authors.forename: Kira
authors.initials: K
authors.lastname: Leishear
authors.affiliation: Epidemiology Branch, Division of Intramural Population Health Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Rockville, MD.
authors.forename: Pauline
authors.initials: P
authors.lastname: Mendola
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D005865:Gestational Age; D006801:Humans; D015994:Incidence; D054582:National Institute of Child Health and Human Development (U.S.); D011247:Pregnancy; D047928:Premature Birth / Q000145:classification* / Q000453:epidemiology; D012008:Recurrence; D012189:Retrospective Studies; D012306:Risk; D014481:United States; D014589:Utah / Q000453:epidemiology; D055815:Young Adult
keywords: indicated preterm birth; recurrent preterm birth; spontaneous preterm birth
references.citation: N Engl J Med. 2003 Jun 12;348(24):2379-85
references.pmid: 12802023
references.citation: Clin Obstet Gynecol. 1984 Sep;27(3):539-52
references.pmid: 6541539
references.citation: Br J Obstet Gynaecol. 1985 Sep;92(9):921-8
references.pmid: 4041398
references.citation: Am J Epidemiol. 1999 Oct 1;150(7):756-62
references.pmid: 10512429
references.citation: Obstet Gynecol. 2001 Sep;98(3):379-85
references.pmid: 11530116
references.citation: Am J Obstet Gynecol. 2007 Jun;196(6):576.e1-6; discussion 576.e6-7
references.pmid: 17547902
references.citation: Stat Methods Med Res. 2006 Apr;15(2):103-26
references.pmid: 16615652
references.citation: JAMA. 2000 Mar 22-29;283(12):1591-6
references.pmid: 10735396
references.citation: Am J Obstet Gynecol. 1973 Sep 1;117(1):1-9
references.pmid: 4722373
references.citation: Am J Obstet Gynecol. 2006 Apr;194(4):1176-84; discussion 1184-5
references.pmid: 16580328
references.citation: BJOG. 2013 Jun;120(7):863-72
references.pmid: 23418923
references.citation: N Engl J Med. 1996 Feb 29;334(9):567-72
references.pmid: 8569824
references.citation: Natl Vital Stat Rep. 2010 Dec 8;59(1):1, 3-71
references.pmid: 22145497
references.citation: Obstet Gynecol. 1995 Nov;86(5):800-4
references.pmid: 7566852
references.citation: Obstet Gynecol. 2010 Nov;116(5):1047-55
references.pmid: 20966688
references.citation: Am J Obstet Gynecol. 2006 Sep;195(3):643-50
references.pmid: 16949395
references.citation: Am J Obstet Gynecol. 1999 Nov;181(5 Pt 1):1216-21
references.pmid: 10561648