Table 1.

Secondary endpoints and their definition

Secondary endpoint	Definition
Fertility outcomes
Positive pregnancy test	Serum hCG >5 mIU/mL after the completion of the first transfer
Clinical pregnancy	≥1 gestational sac on ultrasound at 7 weeks’ gestation with the detection of heart beat activity after the completion of the first transfer
Ongoing pregnancy	Pregnancy with detectable heart rate at ≥12 weeks’ gestation after the completion of the first transfer
Number of top-quality embryos	Based on Istanbul consensus criteria16
Number of freezable embryos	Number of frozen embryos after completion of the first transfer
Time to ongoing pregnancy	Time from randomisation to detection of ongoing pregnancy after completion of the first transfer
Cumulative ongoing pregnancy rate	Ongoing pregnancy rate at 6 and 12 months after randomisation
Maternal safety
OHSS	Classified as moderate or severe using a flow diagram developed for use in clinical trials17
Pregnancy complications*
Ectopic pregnancy	Implantation outside the uterine cavity
Miscarriage	Pregnancy loss at <12 weeks
Multiple pregnancy	≥1 gestational sac at early pregnancy ultrasound (6–8 weeks’ gestation)
Multiple delivery	Birth of ≥1 baby beyond 24 weeks’ gestation
Obstetric and perinatal complications*
Gestational diabetes mellitus	Development of diabetes during pregnancy
Hypertensive disorders of pregnancy	Pregnancy-induced hypertension, pre-eclampsia and eclampsia18
Antepartum haemorrhage	Including placenta previa, placenta accreta and unexplained
Preterm delivery	Delivery at <24, <28, <32, <37 completed weeks
Spontaneous preterm birth	Delivery at <24, <28, <32, <37 completed weeks
Iatrogenic preterm birth	Delivery at <24, <28, <32, <37 completed weeks
Birth weight	In grams; of singletons and twins
Low birth weight	<2500 g at birth
Very low birth weight	<1500 g at birth
High birth rate	>4000 g at birth
Very high birth rate	>4500 g at birth
Large for gestational age	Birth weight >90th centile for gestation, based on standardised ethnicity-based charts
Small for gestational age	Birth weight <10th centile for gestation, based on standardised ethnicity-based charts
Neonatal complications*
Congenital anomaly	Diagnosed at birth (any congenital anomaly included)
Admission to NICU	Admission of neonate to NICU

*All assessed after completion of the first transfer, at 6 months after randomisation and at 12 months after randomisation.

hCG, human chorionic gonadotropin; NICU, neonatal intensive care unit; OHSS, ovarian hyperstimulation syndrome.