Low-dose aspirin in prevention and treatment of intrauterine growth retardation and pregnancy-induced hypertension

Meta-analysis of data from several controlled trials has shown that low-dose aspirin reduces the risk of pregnancy-induced hypertension (PIH) and intrauterine growth retardation (IUGR) in women at high risk of these disorders. We have assessed the efficacy of low-dose aspirin in women judged to be at moderate risk. Women were included on prophylactic criteria--age under 18 or over 40 years, mild or moderate chronic hypertension (diastolic pressure between 90 and 110 mm Hg), nephropathy with normal renal function and blood pressure, history of PIH or IUGR, and twin pregnancy--or therapeutic criteria--PIH or early signs of IUGR in current pregnancy. Eligible women were randomly assigned treatment with 50 mg aspirin daily until delivery (583) or no treatment (523); 18 and 46 women, respectively, were lost to follow-up. The groups were well matched for baseline characteristics. We found no differences between the no-treatment and aspirin groups in numbers of spontaneous (5 vs 2) or therapeutic (1 vs 2) abortions, stillbirths (14 vs 13), perinatal mortality (35.7 vs 28.6 per 1000 births), mean birthweight (2858 [SD 729] vs 2874 [795] g), proportion of infants with birthweights below the 10th centile (95 [18.3%] vs 117 [19.0%]), or births before 37 weeks' gestation (184 [35.6%] vs 209 [33.9%]). Nor did the groups differ in the frequency of PIH with or without proteinuria (51 [15.2%] vs 81 [19.3%]). There was no difference in mean birthweight between the treatment groups in separate analyses according to criteria for trial entry and week of gestation at randomisation. Our study gives little support to the notion that low-dose aspirin is beneficial in women at moderate risk of PIH or IUGR.