Nick S. Macklon

Multiple birth resulting from ovarian stimulation for subfertility treatment

Assisted reproductive technologies (ARTs) aim to increase a womans chances of becoming pregnant by bringing many female and male gametes into close proximity. Techniques to achieve this objective include ovarian hyperstimulation by maturation of several oocytes, intrauterine insemination (IUI) of concentrated sperm, or in-vitro fertilisation (IVF) by bringing gametes together outside the female body. The very nature of ovarian hyperstimulation--with or without IUI--enhances the risk of multiple pregnancy (eg, two or more babies). In most IVF cycles, more than one embryo is transferred, again resulting in an increased chance of multiple pregnancy. Developed societies have witnessed a large rise in prevalence of twin, triplet, and higher order multiple births, mainly resulting from ARTs. The primary aim of this Review is to increase awareness of the many implications of the present iatrogenic epidemic of multiple births. The background of ovarian hyperstimulation, trends supporting current practice, and strategies to reduce the chance of multiple pregnancy are highlighted.

Female reproductive ageing: current knowledge and future trends

Over the past few decades, postponement of childbearing has led to a decrease in family size and increased rates of age-related female subfertility. Age-related decrease in ovarian follicle numbers and a decay in oocyte quality dictate the occurrence of natural loss of fecundity and, ultimately, menopause. The rate of this ovarian ageing process is highly variable among women. Identification of women who have severely decreased ovarian reserve for their age is, therefore, clinically relevant. Endocrine and imaging tests for ovarian reserve relate mainly to the quantitative aspect of ovarian reserve, but their capacity to predict the chances for pregnancy is limited. Genetic factors regulating the size of the follicle pool and the rate of its depletion might be identified in the near future and, possibly, assist the accurate prediction of a womans reproductive lifespan.

Embryonic implantation: cytokines, adhesion molecules, and immune cells in establishing an implantation environment.

Successful implantation is an absolute requirement for the reproduction of species, including humans. The process by which a foreign blastocyst is accepted by the maternal endometrium is complex and requires interplay of many systems. Implantation occurs during the putative implantation window, in which the maternal endometrium is ready to accept the blastocyst, which on the other hand, also plays a specific role. It produces cytokines and chemokines and expresses adhesion molecules and certain classes of MHC molecules. We review the most important players in implantation. Concerning the cytokines, the establishment of controlled aggression is key; an excess of pro‐ or anti‐inflammation is detrimental to pregnancy outcome. Chemokines control the orientation of the embryo. The adhesion molecules are necessary to establish the required physical interaction between mother and blastocyst. Finally, immune cells and in particular, uterine NK and regulatory T cells are pivotal in inducing tolerance to the blastocyst. The aim of this review is to discuss mechanisms at play and their relative importance to the establishment of pregnancy.

Anti-Müllerian hormone (AMH): what do we still need to know?

In the ovary, Anti-Müllerian hormone (AMH) is produced by the granulosa cells of early developing follicles and inhibits the transition from the primordial to the primary follicular stage. AMH levels can be measured in serum and have been shown to be proportional to the number of small antral follicles. In women serum AMH levels decrease with age and are undetectable in the post-menopausal period. In patients with premature ovarian failure AMH is undetectable or greatly reduced depending of the number of antral follicles in the ovaries. In contrast, AMH levels have been shown to be increased in women with polycystic ovary syndrome (PCOS). AMH levels appear to represent the quantity of the ovarian follicle pool and may become a useful marker of ovarian reserve. AMH measurement could also be useful in the prediction of the extremes of ovarian response to gonadotrophin stimulation for in vitro fertilization, namely poor- and hyper-response. Although AMH has the potential to increase our understanding of ovarian pathophysiology, and to guide clinical management in a broad range of conditions, a number of important questions relating to both the basic physiology of AMH and its clinical implications need to be answered.

Why do couples drop-out from IVF treatment? A prospective cohort study

BACKGROUND Cumulative IVF pregnancy rates are compromised by the large number of couples who drop-out of treatment before achieving pregnancy. The aim of this study was to identify the role of the treatment strategy applied, and potential other factors that influence the decision of couples to discontinue treatment. METHODS The incidence of drop-out from IVF treatment and factors related to drop-out were studied in a cohort of IVF patients aged <38 years embarking on IVF treatment either with a mild or a standard treatment strategy for a planned maximum number of treatment cycles. RESULTS Of the 384 couples studied, 17% dropped out of IVF treatment. The physical or psychological burden of treatment was the most frequent cause of drop-out (28%). The application of a mild treatment strategy (mild ovarian stimulation along with the transfer of a single embryo) significantly reduced the chance of drop-out (hazard ratio (HR) 0.55; 95% confidence interval (CI), 0.31-0.96). When a mild IVF strategy was employed, the association between the baseline anxiety score and drop-out was reduced by >50%. The presence of severe male subfertility (HR 4.80; 95% CI, 1.63-14.13) and the failure to achieve embryo transfer (odds ratio 0.41; 95% CI, 0.24-0.72) were also related to drop-out. CONCLUSIONS Reducing drop-out rate is crucial to further improve the efficacy and cost-effectiveness of IVF treatment. An important factor determining the risk of drop-out is the burden of the treatment strategy. The application of a mild treatment strategy and managing patients expectations might reduce drop-out rates.

Natural Selection of Human Embryos: Impaired Decidualization of Endometrium Disables Embryo-Maternal Interactions and Causes Recurrent Pregnancy Loss

Background Recurrent pregnancy loss (RPL), defined as 3 or more consecutive miscarriages, is widely attributed either to repeated chromosomal instability in the conceptus or to uterine factors that are poorly defined. We tested the hypothesis that abnormal cyclic differentiation of endometrial stromal cells (ESCs) into specialized decidual cells predisposes to RPL, based on the observation that this process may not only be indispensable for placenta formation in pregnancy but also for embryo recognition and selection at time of implantation. Methodology/Principal Findings Analysis of mid-secretory endometrial biopsies demonstrated that RPL is associated with decreased expression of the decidual marker prolactin (PRL) but increased levels of prokineticin-1 (PROK1), a cytokine that promotes implantation. These in vivo findings were entirely recapitulated when ESCs were purified from patients with and without a history of RPL and decidualized in culture. In addition to attenuated PRL production and prolonged and enhanced PROK1 expression, RPL was further associated with a complete dysregulation of both markers upon treatment of ESC cultures with human chorionic gonadotropin, a glycoprotein hormone abundantly expressed by the implanting embryo. We postulated that impaired embryo recognition and selection would clinically be associated with increased fecundity, defined by short time-to-pregnancy (TTP) intervals. Woman-based analysis of the mean and mode TTP in a cohort of 560 RPL patients showed that 40% can be considered “superfertile”, defined by a mean TTP of 3 months or less. Conclusions Impaired cyclic decidualization of the endometrium facilitates implantation yet predisposes to subsequent pregnancy failure by disabling natural embryo selection and by disrupting the maternal responses to embryonic signals. These findings suggest a novel pathological pathway that unifies maternal and embryonic causes of RPL.

An ultrasound study of gestational and postural changes in the deep venous system of the leg in pregnancy

Objective To investigate gestational and postural changes in diameter and blood flow in the proximal deep leg veins during pregnancy.

Venous thromboembolic disease in obstetrics and gynaecology : the Scottish experience

The incidence and pattern of thromboembolic complications in obstetric and gynaecological patients in Scotland between 1981 and 1992 was investigated by analysing ICD coded data retrieved from the SMR1 and SMR2 database. The effect of mode of delivery and maternal age over 35 on risk of thromboembolism in pregnancy was also assessed. 0.076% of gynaecological episodes were subsequently complicated by thromboembolic events. Nineteen percent of those suffering thromboembolic complications within two weeks of discharge were referred back to gynaecology. The incidence of deep venous thrombosis (DVT) in those under 35 years and over 35 years was 0.615/1000 maternities and 1.216/1000 maternities respectively. Respective figures for postnatal DVT were 0.304/1000 and O. 720/1000 and for pulmonary thromboembolism (PTE), 0.108/ 1000 and 0.405/1000. In both age groups, emergency caesarean section was associated with a higher incidence of DVT than elective caesarean section and vaginal delivery.

Reproductive biology and IVF: ovarian stimulation and endometrial receptivity

The influence of ovarian stimulation on endometrium receptivity has been inadequately addressed in medical literature. Hormonal effects of ovarian stimulation on endometrial changes as compared with the natural cycle should be elucidated and correlated with the potential of the embryo to implant. It is important to distinguish between the endometrial effect of induction of ovulation in anovulatory women and those of ovarian (super)ovulation in ovulatory women. Induction of ovulation leads to in vivo conception whereas ovarian stimulation results in in vitro fertilization. The available data in the field indicate that endometrial changes have an impressive negative influence on the potential of embryonic implantation. The aim of this review is to analyse the effects of gonadotropin, GnRH-agonist and GnRH-antagonist administration on endometrial behaviour, to highlight the gaps in current knowledge and to propose areas in which research is needed.

Mild ovarian stimulation for IVF.

BACKGROUND Mild ovarian stimulation for in vitro fertilization (IVF) aims to achieve cost-effective, patient-friendly regimens which optimize the balance between outcomes and risks of treatment. METHODS Pubmed and Medline were searched up to end of January 2008 for papers on ovarian stimulation protocols for IVF. Additionally, references to related studies were selected wherever possible. RESULTS Studies show that mild interference with the decrease in follicle-stimulating hormone levels in the mid-follicular phase was sufficient to override the selection of a single dominant follicle. Gonadotrophin-releasing hormone antagonists compared with agonists reduce length and dosage of gonadotrophin treatment without a significant reduction in the probability of live birth (OR 0.86, 95% CI 0.72-1.02). Mild ovarian stimulation may be achieved with limited gonadotrophins or with alternatives such as anti-estrogens or aromatase inhibitors. Another option is luteinizing hormone or human chorionic gonadotrophin administration during the late follicular phase. Studies regarding these approaches are discussed individually; small sample size of single studies along with heterogeneity in patient inclusion criteria as well as outcomes analysed does not allow a meta-analysis to be performed. Additionally, the implications of mild ovarian stimulation for embryo quality, endometrial receptivity, cost and the psychological impact of IVF treatment are discussed. CONCLUSIONS Evidence in favour of mild ovarian stimulation for IVF is accumulating in recent literature. However, further, sufficiently powered prospective studies applying novel mild treatment regimens are required and structured reporting of the incidence and severity of complications, the number of treatment days, medication used, cost, patient discomfort and number of patient drop-outs in studies on IVF is encouraged.