Low-dose aspirin for oocyte donation recipients with a thin endometrium: prospective, randomized study

OBJECTIVE: To evaluate the effect of low-dose aspirin use in oocyte donation recipients with an endometrial thickness of < 8 mm. DESIGN: A prospective, randomized study. SETTING: An oocyte donation program in a private infertility practice. PATIENT(S): Twenty-eight recipients undergoing oocyte donation who failed to develop an endometrial thickness of at least 8 mm in a previous evaluation cycle. INTERVENTION(S): Fifteen recipients received low-dose aspirin (81 mg/d) in addition to standard hormone replacement for an oocyte donation cycle. The remaining 13 recipients did not receive aspirin. MAIN OUTCOME MEASURE(S): Clinical pregnancy rates, delivery rates, implantation rates, and change in endometrial thickness were compared in the aspirin and nonaspirin groups. RESULT(S): There was no demonstrable increase in endometrial thickness in the aspirin-treated group. However, there was a statistically significant increase in implantation rates in the aspirin-treated group (24% versus 9%) and in implantation rates and clinical pregnancy rates in the aspirin-treated group when the final endometrial thickness was < 8 mm. CONCLUSION(S): Low-dose aspirin therapy improves implantation rates in oocyte donation recipients with a thin endometrium.