Cytogenetic analysis of unfertilized oocytes retrieved after treatment with the LHRH analogue, buserelin

Chromosome analysis is reported on 155 oocytes from an in-vitro fertilization (IVF) programme in which the LHRH analogue, buserelin, was used in the superovulation regime. Seventy-one oocytes had the normal number of metaphase II chromosomes. Hyperhaploidy was apparent in four cases only; doubling this figure to include the reciprocally formed hypohaploid oocytes gave an aneuploidy rate due to non-disjunction of 10%. This is close to the figure for naturally occurring aneuploidy which may be calculated from data on recognized conceptions at a comparable maternal age. Taken together with the suggestion of a maternal age effect in our series these data suggest that follicular stimulation regimes which precede IVF do not necessarily add to the naturally high aneuploidy rate of the human species. Thirteen oocytes had failed to form the first polar body and the presence of diploid mitotic or sperm chromosomes provided evidence of fertilization and arrested development in 15. These figures for chromosomal anomalies following buserelin treatment are not significantly different from those obtained from comparable surveys following clomiphene citrate stimulation, providing no evidence that the improved pregnancy rate with buserelin is due to chromosomal factors.