Dynamics of early estradiol production may be associated with outcomes of in vitro fertilization

Peri-implantation hormonal milieu: elucidating mechanisms of abnormal placentation and fetal growth

Assisted reproductive technologies (ART) have been associated with several adverse perinatal outcomes involving placentation and fetal growth. It is critical to examine each intervention individually in order to assess its relationship to the described adverse perinatal outcomes. One intervention ubiquitously used in ART is superovulation with gonadotropins. Superovulation results in significant changes in the hormonal milieu, which persist during the peri-implantation and early placentation periods. Epidemiologic evidence suggests that the treatment-induced peri-implantation maternal environment plays a critical role in perinatal outcomes. In this study, using the mouse model, we have isolated the exposure to the peri-implantation period, and we examine the effect of superovulation on placentation and fetal growth. We report that the nonphysiologic peri-implantation maternal hormonal environment resulting from gonadotropin stimulation appears to have a direct effect on fetal growth, trophoblast differentiation, and gene expression. This appears to be mediated, at least in part, through trophoblast expansion and invasion. Although the specific molecular and cellular mechanism(s) leading to these observations remain to be elucidated, identifying this modifiable risk factor will not only allow us to improve perinatal outcomes with ART, but help us understand the pathophysiology contributing to these outcomes.

Potential influence of the microbiome on infertility and assisted reproductive technology

Although an altered vaginal microbiota has been demonstrated to affect parturition, its role in assisted reproductive technologies is uncertain. Nevertheless, the effect of known pathogens such as Mycoplasma tuberculosis, Chlamydia trachomatis, and Neisseria gonorrhoeae is clear, causing subclinical changes thought to be risk factors in subfertility. The Human Microbiome Project (HMP) has allowed for metagenomic studies to aid in characterizing normal vaginal flora. Recent findings from the HMP demonstrate that many different species of Lactobacillus are present in the vaginal tract, with a few that predominate. Studies that characterize the vaginal microbiome in assisted reproductive technology support the hypothesis that colonizing the transfer-catheter tip with Lactobacillus crispatus at the time of embryo transfer may increase the rates of implantation and live birth rate while decreasing the rate of infection. In addition, there is some evidence that a progesterone-resistant endometrium might increase the risk of an abnormal vaginal microbiome.

The dynamics of the vaginal microbiome during infertility therapy with in vitro fertilization-embryo transfer

PURPOSE

To determine the vaginal microbiome in women undergoing IVF-ET and investigate correlations with clinical outcomes.

METHODS

Thirty patients had blood drawn for estradiol (E(2)) and progesterone (P(4)) at four time points during the IVF-ET cycle and at 4-6 weeks of gestation, if pregnant. Vaginal swabs were obtained in different hormonal milieu, and the vaginal microbiome determined by deep sequencing of the 16S ribosomal RNA gene.

RESULTS

The vaginal microbiome underwent a transition during therapy in some but not all patients. Novel bacteria were found in 33% of women tested during the treatment cycle, but not at 6-8 weeks of gestation. Diversity of species varied across different hormonal milieu, and on the day of embryo transfer correlated with outcome (live birth/no live birth). The species diversity index distinguished women who had a live birth from those who did not.

CONCLUSIONS

This metagenomics approach has enabled discovery of novel, previously unidentified bacterial species in the human vagina in different hormonal milieu and supports a shift in the vaginal microbiome during IVF-ET therapy using standard protocols. Furthermore, the data suggest that the vaginal microbiome on the day of embryo transfer affects pregnancy outcome.

Different ART outcomes at increasing peak estradiol levels with long and antagonist protocols: retrospective insights from ten years experience

PURPOSE

To evaluate the impact of high estradiol (E2) levels on assisted reproductive technologies outcomes in high responders (≥12 oocytes retrieved) according to the controlled ovarian stimulation protocol (COS) used.

METHODS

Clinical retrospective evaluation of total, clinical pregnancy and implantation rates in ART cycles performed in high responders according to the COS protocol used (long or antagonist) at Pathophysiology Unit of Human Reproduction and Sperm Bank of Pordenone from June 2000 to December 2010.

RESULTS

In high responders total, clinical and implantation rates were significantly higher in long if compared with antagonist protocol with peak estradiol level ≤3,000 pg/ml; on the contrary there was a significantly higher implantation rate with antagonist than long protocol with peak estradiol >3,000 pg/ml. However in this subgroup of patients total and clinical pregnancy rates showed only a trend favouring antagonist possibly due to a statistical β error.

CONCLUSIONS

In high responders long protocol seems to work better than antagonist when peak E2 is lower than 3,000 pg/ml but the opposite may be true for cycles with higher E2 levels.