Significantly superior response in the right ovary compared with the left ovary after stimulation with follicle-stimulating hormone in a pituitary down-regulation regimen

Objective: To compare the differences between the right and left ovarian responses in patients undergoing standard in vitro fertilization (IVF) treatment. Design: Prospective, observational study. Setting: A university hospital in Taiwan. Patient(s): Seven hundred eighty-nine consecutive patients undergoing IVF or intracytoplasmic sperm injection. Intervention(s): None. Main Outcome Measure(s): The number of oocytes retrieved, fertilization rates, number of grade 1 zygotes and number of embryos produced, embryo arrest-free rate, and mean number of top-quality embryos on the day of transfer. Result(s): The number of follicles >= 16 mm in diameter on day 2.5 versus 2.2 of human chorionic gonadotropin (hCG) administration, the number of follicles >= 10 mm in diameter on hCG day 6.5 versus 6.1, the number of oocytes (3.6 vs. 3.0), the percentage fertilization (79.9 vs. 74.6%), and the mean number of mature oocytes and grade 1 zygotes (2.3 vs. 1.8 and 1.79 vs. 0.93, respectively), and the mean available number of top-quality embryos on transfer day 1.39 versus 0.73 were all statistically significantly greater in the right compared with the left ovary; however, the pregnancy and implantation rates were similar. Conclusion(s): There are statistically significant differences between the right and left ovarian responses in IVF patients with healthy ovaries, and the right ovarian responses are superior to the left ovarian responses. (Fertil Steril (R) 2010;93:2269-73. (C) 2010 by American Society for Reproductive Medicine.)