Definition of clinical outcomes
Clinical pregnancy was defined as the presence of gestational sac at the
6-8 weeks transvaginal ultrasound. Ectopic pregnancy was defined as
gestational sac observed by ultrasound outside the uterine cavity.
Miscarriage was defined as spontaneous loss of a clinical pregnancy
before 24 completed weeks of gestational age, in which the embryo(s) or
fetus(es) is/are nonviable and is/are not spontaneously absorbed or
expelled from the uterus. Preterm birth was defined as a birth that
takes place after 24 weeks and before 37 completed weeks of gestational
age. Live birth was defined as the delivery of at least one live-born
baby beyond 24 weeks of gestational age. Live birth rate was defined as
live deliveries (at least one live birth) per women after embryo
transfer.