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Evidence summaries

Antiplatelet Agents for Preventing Pre-Eclampsia

Low-dose aspirin is effective in prevention of pre-eclampsia. Proteinuric pre-eclampsia is reduced by 18%, fetal or neonatal deaths are reduced by 14%, number of small-for-gestational age babies by 10% and number of preterm births by 9%. Level of evidence: "A"

A meta-analysis 2 included 45 trials with a total of 20 909 pregnant randomized to 50-150 mg of aspirin daily. When aspirin was initiated at HASH(0x2fd0288)16 weeks, there was a significant reduction and a dose-response effect for the prevention of pre-eclampsia (RR 0.57, 95% CI 0.43 to 0.75; P < .001), severe pre-eclampsia (RR 0.47, 95% CI 0.26 to 0.83; P = .009), and fetal growth restriction (RR 0.56, 95% CI 0.44 to 0.70; P < .001) with higher dosages of aspirin being associated with greater reduction of the 3 outcomes. Similar results were observed after the exclusion of studies at high risk of biases. When aspirin was initiated at >16 weeks, there was a smaller reduction of pre-eclampsia. Aspirin initiated at >16 weeks was not associated with a risk reduction or a dose-response effect for severe pre-eclampsia (RR 0.85, 95% CI 0.64 to 1.14; P = .28) and fetal growth restriction (RR 0.95, 95% CI 0.86-1.05; P = .34).

A Cochrane review [Abstract] 1 included 77 studies with a total of 40 249 women. Antiplatelet agent (mostly low-dose aspirin - 50 to150 mg) was compared with placebo/no antiplatelet agent. Antiplatelet agents reduced the risk of proteinuric pre-eclampsia by 18%, number needed to treat for one women to benefit (NNTB) 61 (95% CI 45 to 92). There was a small (9%) reduction in preterm birth <37 weeks, NNTB 61 (95% CI 42 to 114) and a 14% reduction infetal deaths, neonatal deaths or death before hospital discharge, NNTB 197 (95% CI 115 to 681). Antiplatelet agents probably slightly increase postpartum haemorrhage > 500 mL.

Antiplatelet agents compared with no antiplatelet agents/placebo for pre-eclampsia prevention

OutcomeRelative effect(95% CI)Assumed risk- Placebo/no antiplateletCorresponding risk - Antiplatelet agentsNo of Participants(studies)Quality of the evidence
Proteinuric pre-eclampsiaRR 0.82(0.77 to 0.88)92 per 100016 fewer per 1000(22 fewer to 11 fewer)36 716(60) High
Any reported infant death (fetal, neonatal, or before hospital discharge)RR 0.85(0.76 to 0.95)33 per 10005 fewer per 1000(9 fewer to 1 fewer)35 391(52) High
Preterm birth(before 37 weeks' gestation)RR 0.91(0.87 to 0.95)175 per 100016 fewer per 1000(23 fewer to 9 fewer)35 212(47) High
Small-for-gestational ageRR 0.84(0.76 to 0.92)47 per 10007 fewer per 1000(11 fewer to 3 fewer)35 761(50) High
Pregnancy with serious adverse outcome (composite including maternal death, baby death, pre-eclampsia, small-for-gestational age, preterm birth)RR 0.90(0.85 to 0.96)197 per 100020 fewer per 1000(30 fewer to 8 fewer)17 382(13) High
Postpartum haemorrhage > 500 mLRR 1.06(1.00 to 1.12)143 per 10009 more per 1000(0 fewer to 19 more)23 769(19) Moderate

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    References

    • Duley L, Meher S, Hunter KE et al. Antiplatelet agents for preventing pre-eclampsia and its complications. Cochrane Database Syst Rev 2019;2019(10):. [PubMed]
    • Roberge S, Nicolaides K, Demers S et al. The role of aspirin dose on the prevention of preeclampsia and fetal growth restriction: systematic review and meta-analysis. Am J Obstet Gynecol 2017;216(2):110-120.e6. [PubMed]

Primary/Secondary Keywords