BLASTOCYST TRANSFER IN DAY-5 EMBRYO-TRANSFER DEPENDS PRIMARILY ON THENUMBER OF OOCYTES RETRIEVED AND NOT AN AGE

Objective: To analyze the effects of patient age and treatment cycle n umber on the occurrence of-blastocyst transfer and subsequent implanta tion. Design: Prospective study. Setting: Department of endocrinology and reproduction. Patient(s): All 1,099 women had day-5 transfers afte r IVF or intracytoplasmic sperm injection treatment. Intervention(s): All patients were checked for embryo development in vitro in consecuti ve day-5 transfer cycles. Two blastocysts or three lesser-developed em bryos were transferred. Main Outcome Measure(s): Blastocyst formation rate or clinical pregnancy/implantation rate. Result(s): Of 929 patien ts in the first cycle, 545 (59%) had at least one blastocyst available for ET. Among 151 patients with a blastocyst in cycle 1, 77 developed one or more blastocysts in cycle 2 (51%). Fifty of 143 patients witho ut a blastocyst in cycle 1 had at least one blastocyst in cycle 2 (35% ). After subdivision of all day-5 ETs according to the first four cycl es, the following implantation rates per embryo were found for ET with one or more blastocysts: cycle 1 (n = 545), 23%; cycle 2 (n = 264), 2 3%; cycle 3 (n = 110), 14%; and cycle 4 (n = 27), 12%, and with noncav itating embryos, respectively: (n = 384) 6%, (n = 193) 6%, (n = 94) 2% , and (n = 35) 3%. The negative correlation of the age of the woman on blastulation depended primarily on the number of oocytes retrieved. C onclusion(s): The blastocyst implantation rate decreased after cycle 2 . Biologic ovarian age, rather than chronologic age, determines the fr equency of blastocyst transfer or pregnancy rate. (C) 1998 by American Society for Reproductive Medicine.