title: Is low-dose aspirin therapy to prevent preeclampsia more efficacious in non-obese women or when initiated early in pregnancy?
abstract: OBJECTIVE
  Late timing of intervention and maternal obesity are potential explanations for the modest effect of aspirin for preeclampsia prevention. We explored whether low-dose aspirin (LDA) is more effective in women at increased risk when initiated before 16 weeks' gestation or given to non-obese women.
  
  
  METHODS
  Secondary analysis of a trial to evaluate LDA (60 mg/d) for preeclampsia prevention in high-risk women. Participants were randomized to LDA or placebo between 13 and 26 weeks. We stratified the effect of LDA on preeclampsia by (a) timing of randomization (< 16 or ≥ 16 weeks gestation) and (b) body mass index (BMI) class (non-obese and obese). The Breslow-Day test for homogeneity was used to assess for variations in effect of LDA across gestational age and BMI groups.
  
  
  RESULTS
  Of 2503 women, 461 (18.4%) initiated LDA < 16 weeks. LDA effect was not better when initiated < 16 weeks (RR: 0.93, 95% CI: 0.67-1.31) versus ≥ 16 weeks (RR: 0.90, 95% CI: 0.75-1.08), (p value for interaction = 0.87). Similarly, LDA effect was not better in non-obese (RR: 0.91, 95% CI: 0.7-1.13) versus obese women (RR: 0.89, 95% CI: 0.7-1.13), (p value for interaction = 0.85).
  
  
  CONCLUSIONS
  LDA for preeclampsia prevention was not more effective when initiated < 16 weeks or used in non-obese women at risk for preeclampsia. No particular subgroup of women was more or less likely to benefit from LDA therapy.
authors.affiliation: a Center for Women's Reproductive Health at the University of Alabama at Birmingham , Birmingham , AL , USA.
authors.forename: Jessica A
authors.initials: JA
authors.lastname: Cantu
authors.forename: Victoria R
authors.initials: VR
authors.lastname: Jauk
authors.forename: John
authors.initials: J
authors.lastname: Owen
authors.forename: Joseph R
authors.initials: JR
authors.lastname: Biggio
authors.forename: Adi R
authors.initials: AR
authors.lastname: Abramovici
authors.forename: Rodney K
authors.initials: RK
authors.lastname: Edwards
authors.forename: Alan T
authors.initials: AT
authors.lastname: Tita
mesh_terms: D000328:Adult; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000008:administration & dosage / Q000627:therapeutic use*; D001241:Aspirin / Q000008:administration & dosage*; D015992:Body Mass Index; D005260:Female; D005865:Gestational Age; D006801:Humans; D009765:Obesity / Q000150:complications; D010975:Platelet Aggregation Inhibitors / Q000008:administration & dosage*; D011225:Pre-Eclampsia / Q000517:prevention & control*; D011247:Pregnancy; D012307:Risk Factors
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D010975:Platelet Aggregation Inhibitors; D001241:Aspirin
keywords: Aspirin; gestational age; obesity; preeclampsia; prevention