Does low-dose aspirin improve pregnancy rate in IVF/ICSI? A randomized double-blind placebo controlled trial.

BACKGROUND: It has been suggested in the literature that low-dose aspirin leads to an increased number of oocytes in IVF/ICSI as well as a higher pregnancy rate. The aim of the present study was to investigate the effect of daily administration of low-dose aspirin, compared with placebo, on pregnancy rate in IVF and ICSI. METHODS: This study was a prospective, randomized, double-blind placebo controlled trial, performed in the fertility centre of the University Hospital of Ghent. Concealed allocation by computerized randomization was done by the central pharmacy of the hospital. Daily oral administration of aspirin 100 mg or placebo started before stimulation and was continued until confirmation of pregnancy by detection of fetal heart activity on ultrasound. The primary outcome measure assessed in this trial was clinical pregnancy rate per cycle. RESULTS: Two hundred and one couples were included in this study, 193 women (aspirin group n = 97, placebo group n = 96) started treatment and 181 underwent an embryo transfer. There were 31 clinical pregnancies (31/97 or 32%) in the aspirin group versus 30 (30/96 or 31%; P = 0.916; OR 1.033; 95% CI 0.565-1.890) in the placebo group. CONCLUSIONS: This randomized controlled trial could not show a significant difference in clinical pregnancy rate between the aspirin and the placebo group in a first or second IVF/ICSI cycle. Given the lack of evidence for a beneficial effect of low-dose aspirin, it appears that low-dose aspirin should not be prescribed routinely in IVF/ICSI treatment. ClinicalTrials.gov Identifier: NCT00644085.