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.