Many oocytes fail to fertilize and cleave in vitro and many embryos transferred to uterus fail to implant or maintain implantation. Chromosomal abnormalities in the male and female gametes may contribute to this loss. The higher incidence of
meiotic
chromosome abnormalities has been found in oocytes than in sperm. The wide range of incidence of chromosomal abnormalities in unfertilized oocytes has been reported in human IVF program (26-63%). However, factors affecting chromosomal
abnormalities
are
not understood. The present study has been conducted to investigate effects of the method for ovarian hyperstimulation, women's age, and the number of oocytes retrieved per patients on the incidence of numerical chromosomal abnormalities. Five
hundred
eighty four unfertilized metaphase Ⅱ oocytes were subjected to chromosomal analysis. Included unfertilized oocytes were from 220 patients (mean age=32.7±3.0) and three hundred thirty oocytes were legible for analysis. Two hundred fourty five
oocytes
out of 330 (73.3%) were normal, while 38 (11.5%) were hyperploidy, 35 (10.6%) were hypoploidy, and 12 (3.6%) were diploidy. Significant difference in chromosomal abnormalities was not found between two patient groups stimulated by follicular
stimulating
hormone/human menopausal gonadotrophin (FSH/HMG) (25.9%) and gonadotrophin-releasing hormone agonist/follicular stimulating hormone/human menopausal gonadotrophin (GnRHa/FSH/HMG) (28%). There was a tendency of increasing chromosomal abnormalities
in
unfertilized oocytes from older patients (<30 yrs: 20.3%, 30-40 yrs: 26.9%, >34 yrs: 35.3%). The number of oocytes retrieved per patient had no effect the incidence of chromosomal abnormalities (1-5: 31.4%, 6-10: 29.8%, 11-15: 28.6%, >15: 16.5%).
These
results from the present study suggest that the chromosomal abnormalities observed in the unfertilized oocytes has not affected by the stimulation methods, patient's age, and the number of oocytes retrieved per patients.
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