title: Risk for spontaneous preterm birth among inter-racial/ethnic couples.
abstract: OBJECTIVE
  Approximately 10% of US couples are inter-racial/ethnic. Substantial variation in preterm birth (PTB) rates is seen when stratified by race/ethnicity, although most studies focused solely on maternal racial/ethnic demographics. Our aims were to analyze the contribution of paternal in addition to maternal race/ethnicity, and to evaluate risk of spontaneous PTB for previously understudied inter-racial/ethnic couples.
  
  
  METHODS
  California singleton live births from 2007 to 2010 were included. Race/ethnicity was determined based on self-report, obtained from birth certificates and defined as African American (AA), Hispanic, Asian, and White. Logistic regression was used to estimate odds ratios of spontaneous PTB at 20-23, 24-31, 32-36 and <37 weeks of gestation, with White-White couples as reference. Results were stratified by previous PTB, pre-gestational and gestational diabetes and hypertension. To investigate the paternal contribution to the risk for any given maternal race/ethnicity we assessed the rates of PTB among inter-racial/ethnic couples compared to the respective same-race couple. Odds ratios were adjusted for maternal age, parity, BMI, prenatal care, payor status, education and smoking.
  
  
  RESULTS
  Among 1,664,939 live births, 13% (n = 216,417) were born to inter-racial/ethnic couples. Compared to White-White couples, risk for spontaneous PTB was increased across all inter-racial/ethnic couples with a non-White mother, except when the father was Asian. Patterns of association were similar after stratification by previous PTB, hypertension and diabetes. Paternal race/ethnicity was also a significant risk factor for PTB.
  
  
  CONCLUSIONS
  Increased risks for spontaneous PTB were seen in most inter-racial/ethnic couple groupings. In addition to maternal race/ethnicity, paternal race/ethnicity was a significant risk factor in many inter-racial/ethnic couplings. Identifying such different risk profiles based on both maternal and paternal race/ethnicity may offer new lines of research inquiry for the underlying etiologies of PTB.
authors.affiliation: a Division of Neonatal & Developmental Medicine, Department of Pediatrics , Stanford University School of Medicine , Stanford , CA , USA.
authors.forename: Bat Zion
authors.identifier: http://orcid.org/0000-0002-1312-872X
authors.initials: BZ
authors.lastname: Shachar
authors.affiliation: a Division of Neonatal & Developmental Medicine, Department of Pediatrics , Stanford University School of Medicine , Stanford , CA , USA.
authors.forename: Jonathan A
authors.initials: JA
authors.lastname: Mayo
authors.affiliation: b Division of Maternal-Fetal Medicine, Department of Obstetrics & Gynecology , Stanford University School of Medicine , Stanford , CA , USA.
authors.forename: Deirdre J
authors.initials: DJ
authors.lastname: Lyell
authors.affiliation: a Division of Neonatal & Developmental Medicine, Department of Pediatrics , Stanford University School of Medicine , Stanford , CA , USA.
authors.forename: David K
authors.initials: DK
authors.lastname: Stevenson
authors.affiliation: a Division of Neonatal & Developmental Medicine, Department of Pediatrics , Stanford University School of Medicine , Stanford , CA , USA.
authors.forename: Gary M
authors.initials: GM
authors.lastname: Shaw
authors.affiliation: b Division of Maternal-Fetal Medicine, Department of Obstetrics & Gynecology , Stanford University School of Medicine , Stanford , CA , USA.
authors.forename: Yair J
authors.identifier: http://orcid.org/0000-0002-9440-8175
authors.initials: YJ
authors.lastname: Blumenfeld
mesh_terms: D000293:Adolescent; D000328:Adult; D002140:California / Q000453:epidemiology; D015331:Cohort Studies; D005006:Ethnicity; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011247:Pregnancy; D047928:Premature Birth / Q000208:ethnology* / Q000209:etiology; D012307:Risk Factors; D055815:Young Adult
keywords: Interracial/ethnic couples; paternal race/ethnicity; spontaneous preterm birth