Outcomes measures
The primary outcome measure was the cumulative live birth rate within 18 months from the first day of ovarian stimulation. LBR which was calculated by including the first live birth generated during the one complete IVF cycle including fresh and all subsequent FET cycles.
Secondary outcome measures included incidence of premature LH surge (LH ≥10 IU/l), fertilization rate, clinical pregnancy, ongoing pregnancy, live birth rate, miscarriage, multiple pregnancy, and implantation rates in both fresh and FET cycles. Number of cycle cancellations, number of oocytes retrieved, number of obtained oocytes, number of embryos available for transfer, number of cryopreserved embryos, number of FET cycles started, moderate and severe ovarian hyperstimulation syndrome (OHSS), time to ongoing pregnancy were also compared. A baby born alive after 22 weeks gestation was classified as a live birth. Clinical pregnancy was defined as the presence of at least one gestational sac on ultrasound at 6 weeks. Ongoing pregnancy was the presence of at least one foetus with heart pulsation on ultrasound beyond 10 weeks. Miscarriage rate was defined as the number of miscarriages before 22 weeks divided by the number of women with clinical pregnancy. Fertilization rate was the percentage of zygotes with two visible pronuclei among inseminated oocytes. Implantation rate was calculated as the number of gestational sacs seen on scanning divided by the number of embryos replaced. Time to ongoing pregnancy leading to live birth as the time from day of ovarian stimulation to an ongoing pregnancy that led to a live birth.
We analyzed all cycles finished before 18 months after the first day of starting ovarian stimulation - whether cancelled, pregnant, or non - pregnant. To ensure validation of complete cycles, all enrolled subjects agreed to use all frozen embryos before proceeding with a new fresh IVF/ICSI cycle.