title: Maternal characteristics and mid-pregnancy serum biomarkers as risk factors for subtypes of preterm birth.
abstract: OBJECTIVE
  To examine the relationship between maternal characteristics, serum biomarkers and preterm birth (PTB) by spontaneous and medically indicated subtypes.
  
  
  METHODS
  Population-based cohort.
  
  
  METHODS
  California, United States of America.
  
  
  METHODS
  From a total population of 1 004 039 live singleton births in 2009 and 2010, 841 665 pregnancies with linked birth certificate and hospital discharge records were included.
  
  
  METHODS
  Characteristics were compared for term and preterm deliveries by PTB subtype using logistic regression and odds ratios adjusted for maternal characteristics and obstetric factors present in final stepwise models and 95% confidence intervals. First-trimester and second-trimester serum marker levels were analysed in a subset of 125 202 pregnancies with available first-trimester and second-trimester serum biomarker results.
  
  
  METHODS
  PTB by subtype.
  
  
  RESULTS
  In fully adjusted models, ten characteristics and three serum biomarkers were associated with increased risk in each PTB subtype (Black race/ethnicity, pre-existing hypertension with and without pre-eclampsia, gestational hypertension with pre-eclampsia, pre-existing diabetes, anaemia, previous PTB, one or two or more previous caesarean section(s), interpregnancy interval ≥ 60 months, low first-trimester pregnancy-associated plasma protein A, high second-trimester α-fetoprotein, and high second-trimester dimeric inhibin A). These risks occurred in 51.6-86.2% of all pregnancies ending in PTB depending on subtype. The highest risk observed was for medically indicated PTB <32 weeks in women with pre-existing hypertension and pre-eclampsia (adjusted odds ratio 89.7, 95% CI 27.3-111.2).
  
  
  CONCLUSIONS
  Our findings suggest a shared aetiology across PTB subtypes. These commonalities point to targets for further study and exploration of risk reduction strategies.
  
  
  CONCLUSIONS
  Findings suggest a shared aetiology across preterm birth subtypes. Patterns may inform risk reduction efforts.
authors.affiliation: Genetic Disease Screening Program, California Department of Public Health, Richmond, CA, USA.|Department of Epidemiology and Biostatistics, Division of Preventive Medicine and Public Health, University of California, San Francisco School of Medicine, San Francisco, CA, USA.
authors.forename: L L
authors.initials: LL
authors.lastname: Jelliffe-Pawlowski
authors.affiliation: Genetic Disease Screening Program, California Department of Public Health, Richmond, CA, USA.
authors.forename: R J
authors.initials: RJ
authors.lastname: Baer
authors.affiliation: Department of Obstetrics & Gynecology, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: Y J
authors.initials: YJ
authors.lastname: Blumenfeld
authors.affiliation: Department of Epidemiology, University of Iowa, Iowa City, IA, USA.
authors.forename: K K
authors.initials: KK
authors.lastname: Ryckman
authors.affiliation: Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: H M
authors.initials: HM
authors.lastname: O'Brodovich
authors.affiliation: Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, USA.|California Perinatal Quality Care Collaborative, Palo Alto, CA, USA.
authors.forename: J B
authors.initials: JB
authors.lastname: Gould
authors.affiliation: Department of Obstetrics & Gynecology, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: M L
authors.initials: ML
authors.lastname: Druzin
authors.affiliation: Department of Epidemiology and Biostatistics, Division of Preventive Medicine and Public Health, University of California, San Francisco School of Medicine, San Francisco, CA, USA.
authors.forename: Y Y
authors.initials: YY
authors.lastname: El-Sayed
authors.affiliation: Department of Obstetrics & Gynecology, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: D J
authors.initials: DJ
authors.lastname: Lyell
authors.affiliation: Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: D K
authors.initials: DK
authors.lastname: Stevenson
authors.affiliation: Department of Pediatrics, Stanford University School of Medicine, Stanford, CA, USA.
authors.forename: G M
authors.initials: GM
authors.lastname: Shaw
authors.affiliation: Genetic Disease Screening Program, California Department of Public Health, Richmond, CA, USA.
authors.forename: R J
authors.initials: RJ
authors.lastname: Currier
mesh_terms: D000293:Adolescent; D000328:Adult; D000740:Anemia / Q000453:epidemiology; D015415:Biomarkers / Q000097:blood; D001721:Birth Intervals; D002140:California / Q000453:epidemiology; D002585:Cesarean Section / Q000706:statistics & numerical data; D015331:Cohort Studies; D003920:Diabetes Mellitus / Q000453:epidemiology; D005260:Female; D006801:Humans; D006973:Hypertension / Q000453:epidemiology; D007265:Inhibins / Q000097:blood; D016015:Logistic Models; D011247:Pregnancy / Q000097:blood; D011248:Pregnancy Complications / Q000453:epidemiology; D011261:Pregnancy Trimester, First / Q000097:blood; D011262:Pregnancy Trimester, Second / Q000097:blood; D011266:Pregnancy-Associated Plasma Protein-A / Q000032:analysis; D047928:Premature Birth / Q000097:blood* / Q000145:classification / Q000453:epidemiology*; D044469:Racial Groups; D012307:Risk Factors; D055815:Young Adult; D000509:alpha-Fetoproteins / Q000032:analysis
chemical_list: D015415:Biomarkers; D000509:alpha-Fetoproteins; C422362:inhibin A; D007265:Inhibins; D011266:Pregnancy-Associated Plasma Protein-A
keywords: Medically indicated preterm birth; risk factors; serum biomarkers; spontaneous preterm birth