Relationships between the developmental potential of human in-vitro fertilization embryos and features describing the embryo, oocyte and follicle.

This paper investigates the relationship of features of in-vitro fertilization (IVF) embryos and the associated oocyte and follicle to the outcome of transfer. It differs from previous studies in including a range of features (n = 53) and in using class probability tree analysis. This is a non-parametric multivariate method which expresses relationships as simple rules of features characterizing the 'take home baby' and 'no take home baby' (negative pregnancy test) classes of embryo batches. Data were analysed retrospectively. Fifty-three (embryo, oocyte and follicular) features for each of the three embryos in the transferred batch were collected for 200 IVF patients. Each batch of three embryos was described by a representative value for each feature. The relationship between features and outcome of transfer was analysed. Only four of the 53 features were identified as predictive. However, an appropriate combination of these four (embryo grade, cell number, follicle size and follicular fluid volume) achieved satisfactory predictivities while offering a simplified and more quantitative basis than regularly used criteria. The key component of the composite embryo grading allotted by embryologists turned out to be cell number. The existing predictive use of follicular size was corroborated and an independent additional predictive contribution of follicular fluid volume was found. The study also suggests that the 49 remaining features have little additional predictive value.