title: Low-dose aspirin, smoking status, and the risk of spontaneous preterm birth.
abstract: OBJECTIVE
  We evaluated the relationship between aspirin supplementation and perinatal outcomes for potential effect modification by smoking status.
  
  
  METHODS
  A secondary analysis of two multicenter trials for which prophylactic aspirin supplementation was given to either low- or high-risk women for prevention of preeclampsia (PE). We examined the effect of aspirin by smoking status using the Breslow-Day test. Primary outcomes for this analysis were PE and preterm birth (PTB) < 37 weeks. We also examined PTB subtypes, small for gestational age (SGA), and neonatal intensive care unit (NICU) admission.
  
  
  RESULTS
  The effect of prenatal aspirin on the risk of PE did not differ by smoking status (relative risk [RR] 95% confidence interval [CI] for smokers; RR 95% CI for nonsmokers) in low-risk (Breslow-Day p = 0.32) or high-risk (RR 95% CI for smokers; RR 95% CI for nonsmokers) (Breslow-Day p = 0.58) women. Among women at low risk for PE, the effect of aspirin supplementation on PTB was not different for nonsmokers (RR 1.00 [95% CI 0.8-1.3]) or smokers (RR 0.80 [95% CI 0.4-1.7]), (Breslow-Day p = 0.54). Aspirin was protective for PTB in nonsmokers (RR 0.80 [95% CI 0.7-0.9]), but not in smokers (RR 1.1 [95% CI 0.9-1.4]) in the high-risk group (Breslow-Day p = 0.03). Aspirin was also associated with increased spontaneous and early PTB and NICU admission in smokers and not nonsmokers in the high-risk group only.
  
  
  CONCLUSIONS
  Aspirin supplementation was associated with worse outcomes related to preterm birth in smokers in a high-risk but not low-risk cohort.
authors.affiliation: Department of Obstetrics and Gynecology, Division of Maternal Fetal Medicine, Center for Women's Reproductive Health, University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: Adi
authors.initials: A
authors.lastname: Abramovici
authors.affiliation: Department of Obstetrics and Gynecology, Division of Maternal Fetal Medicine, Center for Women's Reproductive Health, University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: Victoria
authors.initials: V
authors.lastname: Jauk
authors.affiliation: Department of Obstetrics and Gynecology, Division of Maternal Fetal Medicine, Center for Women's Reproductive Health, University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: Luisa
authors.initials: L
authors.lastname: Wetta
authors.affiliation: Department of Obstetrics and Gynecology, Division of Maternal Fetal Medicine, Center for Women's Reproductive Health, University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: Jessica
authors.initials: J
authors.lastname: Cantu
authors.affiliation: Department of Obstetrics and Gynecology, Division of Maternal Fetal Medicine, Center for Women's Reproductive Health, University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: Rodney
authors.initials: R
authors.lastname: Edwards
authors.affiliation: Department of Obstetrics and Gynecology, Division of Maternal Fetal Medicine, Center for Women's Reproductive Health, University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: Joseph
authors.initials: J
authors.lastname: Biggio
authors.affiliation: Department of Obstetrics and Gynecology, Division of Maternal Fetal Medicine, Center for Women's Reproductive Health, University of Alabama at Birmingham, Birmingham, Alabama.
authors.forename: Alan
authors.initials: A
authors.lastname: Tita
mesh_terms: D000293:Adolescent; D000328:Adult; D001241:Aspirin / Q000008:administration & dosage* / Q000627:therapeutic use; D015331:Cohort Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007236:Infant, Small for Gestational Age; D007363:Intensive Care Units, Neonatal; D011225:Pre-Eclampsia / Q000517:prevention & control*; D011247:Pregnancy; D011248:Pregnancy Complications / Q000517:prevention & control*; D047928:Premature Birth / Q000517:prevention & control*; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D001241:Aspirin