A retrospective analysis of our in-vitro fertilization (IVF) and oocyte donation programmes was carried out in order to gain clinical knowledge of the factors involved in the aetiology of the endometriosis-associated infertility. Comparison between the IVF outcomes from 96 cycles in 78 patients with tubal infertility and from 96 cycles in 59 women with endometriosis indicates that endometriosis patients have a poor IVF outcome in terms of reduced pregnancy rate per cycle (P < 0.0004), reduced pregnancy rate per transfer (P < 0.002), and reduced implantation rate (P < 0.003). The analysis of patients undergoing oocyte donation for different reasons, including low response with or without endometriosis, showed that patients with this disease have the same chances of implantation and pregnancy as other recipients when the oocytes came from donors without known endometriosis. However, when the results of oocyte donation were classified according to the origin of the oocytes donated, patients who received embryos derived from endometriotic ovaries showed a significantly (P < 0.05) reduced implantation rate as compared to the remaining groups. Taken together, all these observations suggest that infertility in endometriosis patients may be related to alterations within the oocyte, which in turn result in embryos with decreased ability to implant.

Embryos with certain types of chromosomal abnormalities were negatively selected during preimplantation embryo development. Despite this selection, a remarkable percentage of chromosomally abnormal embryos can develop normally to blastocyst stage with high probability of implantation and pregnancy.

Recurrent pregnancy loss (RPL) is a common disorder during early gestation. Recent evidence suggests that T helper 1 (Th1)-type immunity is associated with unsuccessful pregnancy especially in women with RPL of otherwise unknown etiology, while Th2-type immunity is associated with pregnancy success. Interleukin (IL)-1 may influence Th1/Th2 immune responsiveness and has been implicated in the establishment of successful pregnancy. In the present study, we investigated polymorphism of the IL-1␤ gene (IL1B) in women with a history of RPL. Significant increases in the frequencies of IL1B promoter region variants IL1-511C and IL1B-31T were found in women with a history of RPL. Increased frequencies of these two variants and their homozygotes were found only in cases having evidence of Th1 immunity to trophoblast as determined by IFN-␥ production of peripheral blood mononuclear cells (PBMCs) stimulated with a trophoblast cell-line extract. Significantly higher IFN-␥ production by PBMCs in response to trophoblast correlated with variant IL1B-511C and its homozygocity in women with RPL. These results suggest that variants −511C and −31T in the IL1B promoter region confer risk for RPL associated with Th1 immunity to trophoblast antigens.

The environment of the oocyte during its in vivo maturation consists of follicular fluid (FF) and is surrounded by granulosa cells. The FF is derived from the sanguineous plasma and secretions, synthesised in the follicle wall, that contain a large variety of growth factors, cytokines, amino acids, and other metabolites. These metabolites are presumably involved in the physiology of the oocyte. The identification, quantification and study of FF metabolites can provide additional information about the oocyte state which can be helpful in distinguishing those oocytes that have a greater capacity to be fertilised and to develop properly. The aim of this work is to identify the metabolic profile of FF samples exhaustively using High Resolution Nuclear Magnetic Resonance (NMR). A total of 30 FF samples from oocyte donors (<35 years) were analysed. Different monodimensional (1D) and bidimensional (2D) (homo and heteronuclear) NMR experiments were acquired. A total of 131 chemical shifts were assigned and 42 metabolites, including as example glucose, lactate, acetate, acetoacetate, pyruvate and b-hydroxybutyrate, were identified. High correlations were found between these important intermediaries of the energetic metabolic pathways of the follicle which can indicate the importance of these pathways in oocyte development. Some of these identified metabolites might be useful as biomarkers of the follicular maturation state, allowing oocytes with a higher fertilisation potential to be selected, thereby increasing pregnancy rates in women following in vitro fertilisation (IVF) treatments.