DELAYING OVULATION TRIGGERING DOESN'T COMPROMISE CUMULATIVE PREGNANCY RATES IN FROZEN EMBRYO TRANSFER

Abstract

Defining optimal ovulation trigger criteria has been a persistent concern in assisted reproduction technology. The commonly used ultrasound parameter has been the presence of at least 3 follicles ≥17 mm. The impact of delaying ovulation triggering has been studied in fresh embryo transfers with discordant results. Therefore, we queried whether using larger ultrasound criteria and delaying ovulation triggering– by one or two days – increased the number of metaphase II oocytes (MII), usable blastocysts and cumulative clinical pregnancy rates (cCPR) in frozen embryo transfers. All patients performing their first autologous In Vitro Fertilization (IVF) cycle between 1/2017 and 12/2019 with antagonist protocol and frozen embryo transfers in our center were considered. We included only patients with blastocysts transfers. We divided patients into 3 groups constituted as: control group with patients whose ovulation was triggered when > 3 follicles reached >17 mm; the group 1 and 2 had ovulation triggered one and two days, respectively after the forementioned ultrasound criteria were reached. The primary outcome was cCPR. The secondary outcomes were: MIIs number, fertilization, blastulation, implantation and miscarriage rates. Comparisons between the 3 treatment groups were assessed using statistical analysis Chi2 and ANOVA. 1180 patients (598, 449 and 133 in the control group and group 1 and 2, respectively) were analyzed. Patients in group 2 were significantly younger (34.1 years) than those in the control group (35.4) and group 1 (34.9) p=0.01. Ovarian reserve parameters, type of infertility and BMI were similar between the groups. Ovarian stimulation length was approximately 11 days. Analysis of cCPR showed no difference but yet, a trend toward higher values in group 1 (47,7%) and in group 2 (51,1%), as compared to controls (45,3%) p=0.44, paralleling a trend toward more MII (11.4, 11.8 and 12.3 p=0.44) and vitrified blastocysts (3.2, 3.4 and 3.7 p=0.29) in controls and group 1 and 2 respectively. Fertilization, blastulation, implantation and miscarriage rates were similar in all 3 groups. Likewise, no difference was found after adjustment for age. Using larger ultrasound criteria for triggering ovulation in ovarian stimulation doesn’t compromise oocyte quantity nor cCPR when frozen embryos are transferred. Interestingly, using larger ultrasound criteria for triggering ovulation didn’t lengthen ovarian stimulation thereby suggesting that clinicians adjust their judgment when triggering ovulation according to ovarian stimulation duration.