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Recording available 2/16-5/2
Recording available 2/16-5/2
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Abstract Award
Abstract Award
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Foundation Awardee

Poster Session 3

Category: Clinical Obstetrics

Poster Session 3

(795) Climate as a potential modifier of aspirin’s dose–response for preeclampsia prevention: meta-analysis of RCTs

Thursday, February 12, 2026
10:30 AM - 12:00 PM  
Objective:
Higher average daily temperatures have been linked to adverse outcomes such as cardiovascular disease; low dose aspirin is thought to mediate this effect. We aimed to evaluate the dose–response relationship between aspirin and preeclampsia and assess whether this is modified by climate and initiation timing.

Study Design:
We conducted a one-stage dose–response meta-analysis of randomized controlled trials (RCTs) evaluating aspirin for preeclampsia prevention. Eligible RCTs enrolled moderate- or high-risk pregnant individuals randomized to any daily aspirin dose versus placebo/no treatment. Random-effects meta-regression models with restricted cubic splines (REML) were stratified by climate (cool vs warm), defined using annual temperatures (CRU CY v4.09) averaged by trial and dichotomized at the median across included trials (11.9°C). Meta-regression tested interactions between dose, climate and initiation timing (< 16 vs ≥16 weeks).

Results:
Of 51 eligible RCTs, 34 with dose-specific data were included. Aspirin reduced preeclampsia risk in a dose-dependent manner. In warm climates, the dose–response curve was non-linear (LRT p<0.00003), with steepest risk reduction between 100–150 mg/day (Fig. 1A). Predicted RRs versus placebo were 0.66 (95%CI: 0.55–0.79) at 81 mg, 0.51 (0.40–0.65) at 100 mg, and 0.26 (0.14–0.48) at 150 mg (Table 1A). In cooler climates, benefit was more modest and dose-dependent effects less apparent.  Three-way meta-regression confirmed modification by initiation timing (p=0.0004) and by high-dose × warm-climate interaction (p=0.0044), fully explaining between-study heterogeneity (I²=0%) (Table 1B). Subgroup analyses showed strongest benefit in warm climates with initiation ≥16 weeks (RR=0.63 [0.42–0.95]) (Fig. 1B).

Conclusion:

Aspirin’s effectiveness varies by dose, timing of initiation, and climate. In warm climates, ≥150 mg/day started ≥16 weeks reduced risk by 74%. Climate may proxy other modifiers, but its strong interaction with dose suggests relevance for precision prevention and supports geographically informed prophylaxis and policies aimed at climate stabilization.