Influence of human embryo cultivation in a classic CO2 incubator with 20% oxygen versus benchtop incubator with 5% oxygen on live births: the randomized prospective trial.

SummaryOur objective was to assess the effect of benchtop incubators with low oxygen concentrations on the clinical and embryological parameters of our patients. We conducted a prospective, randomized, opened controlled trial on infertile patients in stimulated cycles. In total, 738 infertile patients were assessed for eligibility and, after final exclusions, 230 patients were allocated either to a 5% O2 group (benchtop incubator) or a 20% O2 group (classic incubator). Finally, 198 patients in the 5% O2 group and 195 in the 20% O2 group were analysed. The outcomes measured were fertilization rate, clinical pregnancy rate, and live birth rate. The primary outcome - live birth rate per all transfers - did not show any improvement in the 5% oxygen group over the 20% oxygen group (25.3% versus 22.6%, P=0.531), but the number of day 5 blastocysts was significantly higher (P=0.009). Fertilization rate did not show any beneficial effect of reduced oxygen (5%) (73.4%±22.4% versus 74.6%±24.0%, P=0.606) per all transfers but there was statistically significant difference in the day 5 SET subgroup (85.3±15.1 versus 75.1±17.5; P=0.004). Clinical pregnancy rate showed results in favour of the 5% oxygen group for all subgroups (day 3: 23.7% versus 21.1%, P=0.701; day 5 SET: 35.0% versus 30.6%. P=0.569) but showed statistical significance only in the day 5 SET subgroup (51.1% versus 29.8%; P=0.038). Culturing of embryos in benchtop incubators under low oxygen produced more blastocysts and therefore was a better alternative for embryo selection, which resulted in higher pregnancy rates. To achieve higher live birth rates, embryo quality is not the only factor.

Current Preventive Strategies for Preovulatory Progesterone Elevation During Ovarian Stimulation for In Vitro Fertilization

The purpose of this review is to present contemporary measures for preventing the increase in preovulatory progesterone (P) and its adverse effects on ovarian stimulation in in vitro fertilization (IVF). For the last 20 years, the increase of preovulatory P has been a topic of numerous discussions because its role is not fully understood in terms of its impact on pregnancy outcome after IVF. Some studies failed to establish a connection between the preovulatory P increase and successful IVF outcome regardless of the level of P, while, conversely, most other studies have reported on adverse effects of elevated P concentrations. Current strategies to prevent the increase in preovulatory P include an individualized approach with the use of mild stimulation protocols and early application of human chorionic gonadotropin for ovulation induction among good responders, delay in the transfer of fresh embryos from 3rd to 5th day, and cryopreservation of all embryos with the thawed embryo transfer in the natural cycle. Nevertheless, further studies are needed to confirm the current preventive methods or enable the application of new strategies in order to lower or eliminate the detrimental effects of preovulatory P rise during ovarian stimulation in IVF.

Dopamine agonists in prevention of ovarian hyperstimulation syndrome.

The aim of this review is to analyze the efficacy of different dopamine agonists in the prevention of ovarian hyperstimulation syndrome (OHSS). Cabergoline, quinagolide and bromocriptine are the most common dopamine agonists used. There are wide clinical variations among the trials in the starting time (from the day of human chorionic gonadotrophin (hCG) to the day following oocyte retrieval); the duration of the treatment (4-21 days), the dose of cabergoline (0.5 mg or 0.25 mg orally) and in the regimens used. At present, the best known effective regimen is 0.5 mg of cabergoline for 8 days or rectal bromocriptine at a daily dose of 2.5 mg for 16 days. Dopamine agonists have shown significant evidences of their efficacy in the prevention of moderate and early-onset OHSS (9.41%), compared with a placebo (21.45%), which cannot be confirmed for the treatment of late OHSS. It would be advisable to start with the treatment on the day of hCG injection or preferably a few hours earlier. The use of dopamine agonists should be indicated in patients at high risk of OHSS, as well as in patients with a history of previous OHSS even without evident signs of the syndrome.

Follicular progesterone elevations with ovulation induction for IVF.

The purpose of this review is to analyse the sources and effects of follicular progesterone elevations during ovarian stimulation, with the underlying mechanisms and preventive strategies on the in vitro fertilisation pregnancy outcome. In the early follicular phase, a flare-up effect of gonadotrophin releasing hormone (GnRH) agonists and incomplete luteolysis in GnRH antagonist regimens can result in significant elevations of progesterone. In the late follicular phase, progesterone elevations in GnRH analogue cycles are the result of the ovarian stimulation itself, driven by high follicle stimulating hormone dosage, estradiol levels, the number of follicles and oocytes. It seems that progesterone elevations (> or = 1.5 ng/mL or 4.77 nmol/L) have a detrimental effect on the outcome of pregnancy, accelerating the endometrial maturation. The most appropriate choice to avoid the negative effects of follicular progesterone elevations is to cancel fresh embryo transfer and to transfer frozen-thawed embryos in natural cycles. To prevent follicular phase elevations it might be preferable to use milder stimulation protocols, earlier trigger of ovulation in high responders and single-blastocyst transfer on day 5. The optimal GnRH analogue protocols during the entire stimulation period appear to be the long agonist as well as "long" and long GnRH antagonist regimens.