In a general IVF population, GnRH antagonists are associated with lower ongoing pregnancy rates when compared to long protocol agonists, but also with lower OHSS rates. Within this population, antagonist treatment prevents one case of OHSS in 40 patients but results in one less ongoing pregnancy out of every 28 women treated. Thus standard use of the long GnRH agonist treatment is perhaps still the approach of choice for prevention of premature luteinization. In couples with PCOS and poor responders, GnRH antagonists do not seem to compromise ongoing pregnancy rates and are associated with less OHSS and therefore could be considered as standard treatment.

The purpose of this review is to examine whether the time has come to replace clomiphene citrate (CC) as the first line therapy for WHO group II (eu-oestrogenic) infertility, the majority of which is associated with polycystic ovary syndrome. CC has been the first line therapy for these cases for the last 40 years. It is a simple, cheap treatment, almost devoid of side effects which yields a single live birth rate of approximately 25% of starters. Non-response to CC and the gap between ovulation and pregnancy rates have variously been attributed to its anti-estrogen effects, and high LH and androgen concentrations. Three possible contenders for the replacement of CC as first-line treatment are scrutinized: metformin, aromatase inhibitors and low-dose FSH. Each has their advantages and disadvantages, but none of them, while showing much potential promise, has been proven, as yet, to be a feasible replacement for CC in this role. For CC, it may not yet be the end of an era but it may be the beginning of the end.

Of the couples unable to conceive without any identifiable cause, 30% are defined as having unexplained infertility. Management depends on duration of infertility and age of female partner. This review describes and comments on the definition and evidence for the management of unexplained infertility. A literature search was conducted in EMBASE, Medline, Ovid and Cochrane Database of Systematic reviews using the terms 'infertility', 'unexplained infertility', 'idiopathic infertility', 'definition of infertility', 'treatment options', 'intrauterine insemination', 'ovulation induction', 'Fallopian tube sperm', 'GIFT' and 'IVF'. There is no uniform definition for unexplained infertility. This varies in the literature depending on the duration of infertility and the age of the female partner. The treatment of unexplained infertility is empirical and many different regimens have been used. Among these are expectant management, ovulation stimulation with clomiphene citrate, gonadotrophins and aromatase inhibitors, Fallopian tube sperm perfusion, tubal flushing, intrauterine insemination, gamete intra-Fallopian transfer and IVF. The standard protocol is to progress from low-technology to high-technology treatment options. On the best available evidence, an algorithm for management is suggested. There is a definite need for multicentre randomized controlled trials to identify the best treatment option in unexplained infertility using a standard definition.

repaired or not, does not preclude patients from holding an ordinary driving licence." Possibly this statement should be extended to include suggestions relating to screening of patients of the relevant age group and sex to identify such high risk disease.

None.

Objective To summarize promising areas of investigation into polycystic ovary syndrome (PCOS) and to stimulate further research in this area. Summary Potential areas of further research activity include the analysis of predisposing conditions that increase the risk of PCOS, particularly genetic background and environmental factors, such as endocrine disruptors and lifestyle. The concept that androgen excess may contribute to insulin resistance needs to be re-examined from a developmental perspective, since animal studies have supported the hypothesis that early exposure to modest androgen excess is associated with insulin resistance. Defining alterations of steroidogenesis in PCOS should quantify ovarian, adrenal and extraglandular contribution, as well as clearly define blood reference levels by some universal standard. Intraovarian regulation of follicle development and mechanisms of follicle arrest should be further elucidated. Finally, PCOS status is expected to have long-term consequences in women, specifically the development of type 2 diabetes, cardiovascular diseases and hormone dependent cancers. Identifying susceptible individuals through genomic and proteomic approaches would help to individualize therapy and prevention. A potential limitation of our review is that we focused selectively on areas we viewed as the most controversial.

The treatment of infertile women with polycystic ovary syndrome (PCOS) is surrounded by many controversies. This paper describes, on the basis of the currently available evidence, the consensus reached by a group of experts regarding the therapeutic challenges raised in these women. Before any intervention is initiated, preconceptional counselling should be provided emphasizing the importance of life style, especially weight reduction and exercise in overweight women, smoking and alcohol consumption. The recommended first-line treatment for ovulation induction remains the anti-estrogen clomiphene citrate (CC). Recommended second-line intervention, should CC fail to result in pregnancy, is either exogenous gonadotrophins or laparoscopic ovarian surgery (LOS). The use of exogenous gonadotrophins is associated with increased chances for multiple pregnancy and, therefore, intense monitoring of ovarian response is required. LOS alone is usually effective in <50% of women and additional ovulation induction medication is required under those circumstances. Overall, ovulation induction (representing the CC, gonadotrophin paradigm) is reported to be highly effective with a cumulative singleton live birth rate of 72%. Recommended third-line treatment is in vitro fertilization. More patient-tailored approaches should be developed for ovulation induction based on initial screening characteristics of women with PCOS. Such approaches may result in deviation from the above mentioned first-, second- or third-line ovulation strategies in well-defined subsets of patients. Metformin use in PCOS should be restricted to women with glucose intolerance. Based on recent data available in the literature, the routine use of this drug in ovulation induction is not recommended. Insufficient evidence is currently available to recommend the clinical use of aromatase inhibitors for routine ovulation induction. Even singleton pregnancies in PCOS are associated with increased health risk for both the mother and the fetus.

A pregnancy rate of approximately 15% per cycle renders the process of human reproduction inefficient. The cycle-dependent expression of molecules involved in the embryo-endometrial dialogue has lead to the identification of a 'window of implantation'. This is the unique temporal and spatial expression of factors that allows the embryo to implant (via signalling, appositioning, attachment and invasion) in a specific time frame of 48 h, 7-10 days after ovulation. Integrin molecules, L-selectin ligands, mucin-1, heparin-binding epidermal growth factor and pinopodes are involved in appositioning and attachment. The embryo produces cytokines and growth factors [interleukins, prostaglandins, vascular endothelial growth factor (VEGF)] and receptors for endometrial signals (leukaemia inhibitory factor receptor, colony stimulating factor receptor, insulin-like growth factors and heparin binding epidermal growth factor receptor). The immune system plays an important role. Immunomodulatory factors such as glycodelin, inhibin and interleukin prevent a graft-versus-host reaction. Angiogenesis controlled by VEGF and prostaglandins is needed for formation of a receptive endometrium and a placenta. Identification of these factors has led to their use as markers of implantation that may identify defects causing subfertility. An ideal marker of implantation is sensitive and specific, and easy to obtain without disturbing implantation. Glycodelin and leukaemia inhibitory factor (serum) and integrins and pinopodes (biopsies) are promising candidates.