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This prospective randomized study investigated whether the developmental potential of in-vitro matured (IVM) human oocytes is improved by follicle stimulating hormone (FSH) priming before aspiration. Normally cycling women were recruited among couples referred for in-vitro fertilization or intracytoplasmic sperm injection because of male factor and/or tubal disease. In the first experiment, 20 women were randomly allocated to either no stimulation (n = 10) or stimulation for 3 days with rec-FSH (Gonal-F, Serono) at a fixed dose of 150 IU/day from day 3 (n = 10). The oocytes were aspirated when the follicle(s) was observed to be 10 mm and matured in vitro for 36 h. In experiment 2, 12 women received rec-FSH (150 IU/daily) from day 3. In five patients stimulation was given for 3 days and aspiration performed as in the first experiment; the remaining seven patients continued stimulation until follicles were 10 mm in diameter and aspiration was performed 72 h later. All the oocytes were cultured for 48 h. FSH priming did not increase the number of oocytes obtained per aspiration and did not improve on maturation to metaphase II, cleavage rate or embryo development. The implantation potential of IVM embryos may be improved by maturation for 36 h compared to 48 h. In the first experiment, five out of 20 patients (25%) obtained a clinical pregnancy with an implantation rate of 15% (5/33). One has delivered a healthy boy and three pregnancies are ongoing beyond 32 gestational weeks. In the second experiment, an implantation rate of 7% and a single pregnancy (8%) was obtained, with delivery of a healthy girl.

ObjectiveTo compare the ongoing pregnancy rate between a freeze-all strategy and a fresh transfer strategy in assisted reproductive technology treatment.DesignMulticentre, randomised controlled superiority trial.SettingOutpatient fertility clinics at eight public hospitals in Denmark, Sweden, and Spain.Participants460 women aged 18-39 years with regular menstrual cycles starting their first, second, or third treatment cycle of in vitro fertilisation or intracytoplasmic sperm injection.InterventionsWomen were randomised at baseline on cycle day 2 or 3 to one of two treatment groups: the freeze-all group (elective freezing of all embryos) who received gonadotropin releasing hormone agonist triggering and single frozen-thawed blastocyst transfer in a subsequent modified natural cycle; or the fresh transfer group who received human chorionic gonadotropin triggering and single blastocyst transfer in the fresh cycle. Women in the fresh transfer group with more than 18 follicles larger than 11 mm on the day of triggering had elective freezing of all embryos and postponement of transfer as a safety measure.Main outcome measuresThe primary outcome was the ongoing pregnancy rate defined as a detectable fetal heart beat after eight weeks of gestation. Secondary outcomes were live birth rate, positive human chorionic gonadotropin rate, time to pregnancy, and pregnancy related, obstetric, and neonatal complications. The primary analysis was performed according to the intention-to-treat principle.ResultsOngoing pregnancy rate did not differ significantly between the freeze-all and fresh transfer groups (27.8% (62/223) v 29.6% (68/230); risk ratio 0.98, 95% confidence interval 0.87 to 1.10, P=0.76). Additionally, no significant difference was found in the live birth rate (27.4% (61/223) for the freeze-all group and 28.7% (66/230) for the fresh transfer group; risk ratio 0.98, 95% confidence interval 0.87 to 1.10, P=0.83). No significant differences between groups were observed for positive human chorionic gonadotropin rate or pregnancy loss, and none of the women had severe ovarian hyperstimulation syndrome; only one hospital admission related to this condition occurred in the fresh transfer group. The risks of pregnancy related, obstetric, and neonatal complications did not differ between the two groups except for a higher mean birth weight after frozen blastocyst transfer and an increased risk of prematurity after fresh blastocyst transfer. Time to pregnancy was longer in the freeze-all group.ConclusionsIn women with regular menstrual cycles, a freeze-all strategy with gonadotropin releasing hormone agonist triggering for final oocyte maturation did not result in higher ongoing pregnancy and live birth rates than a fresh transfer strategy. The findings warrant caution in the indiscriminate application of a freeze-all strategy when no apparent risk of ovarian hyperstimulation syndrome is present.Trial registrationClinicaltrials.gov NCT02746562.

The PN morphology changes over time, indicating that the single light microscopy observation approach is deficient in comparison to time-lapse. Although the assessment of the PN morphology does not improve embryo selection, the timing of PNB should be included in embryo selection parameters.

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