Physiology: Follicular volume and number during in-vitro fertilization: association with oocyte developmental capacity and pregnancy rate

This study examined the effect of the number of follicles aspirated during egg retrieval on pregnancy likelihood during an ovulation induction, in-vitro fertilization (IVF) programme. In addition, the volume of each individual follicle was related to the probability of obtaining an oocyte from that follicle. Its capacity to be fertilized, the incidence of polyspermic fertilization, the quality of early embryos derived from that oocyte and the influence of patient age were the other outcomes studied. Large follicular number and high mean follicular volume related positively to pregnancy outcome. Successful egg retrieval, normal fertilization and good embryo quality were more likely with increasing individual follicular volume. A model was constructed to quantify the predictive value of follicular fluid volume on the developmental potential of individual oocytes and embryos derived from that follicle. Successful outcome of IVF is more likely if ovulation induction results in many follicles, particularly if they have a high mean volume. Individual oocyte and embryo quality can be traced back to the follicular level.