Comparison of fertilization and embryonic development in sibling in vivo matured oocytes retrieved from different sizes follicles from in vitro maturation cycles

To examine the fertilization and developmental potential of sibling mature oocytes collected from different follicle sizes on day of retrieval in in vitro maturation (IVM) cycles. Two hundred thirty eight hCG-primed IVM cycles were performed in 213 patients with polycystic ovaries. If sibling mature oocytes were retrieved on day of collection, they were divided into two groups, Group 1 (n = 78): M-II oocytes obtained from follicles size 10-14 mm; Group 2 (n = 192): M-II oocytes obtained from follicles size < 10 mm. Of the 238 cycles, 63 cycles had more than one M-II oocytes retrieved (total M-II oocytes = 270) both from Groups 1 and 2. There were no significant differences between the two groups for oocyte diameter (117.2 mm vs. 116.9 mm), fertilization (79.5% vs. 72.4%) and good quality embryo on day 3 (66.1% vs. 56.8%). The M-II oocytes retrieved from the cohort of follicles (< 10 mm diameter) can produce the same quality of embryos as that from large follicles, likely contributing to improve the clinical outcome.