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. 2021 Feb 4;2021(2):CD011184. doi: 10.1002/14651858.CD011184.pub3

NCT02570386.

Study name Clinical effectiveness of frozen thawed embryo transfer compared to fresh embryo transfer
Methods RCT
Estimated enrolment: 800
Participants Women aged 18‐42
Inclusion criteria:

  • Women < 42 years of age

  • Presence of at least 3 embryos suitable to freeze on day 2 or 3 following fertilisation based on the centre's criteria

  • Written informed consent


Exclusion criteria:

  • Women using donor eggs/donor sperm

  • Women undergoing pre‐implantation genetic diagnosis

  • Women with abnormal uterine cavity shown on HSG or saline infusion sonogram

  • Women with hydrosalpinges shown on scanning and not treated

  • Women with excessive ovarian response at risk of OHSS where elective freeze is already planned

  • Women with serum progesterone level on day of hCG > 1.5 ng/mL or 5 nmol/L

  • Women whose embryos have previously not survived freeze‐thawing

  • Fresh transfer is planned, e.g. women with endometriosis or adenomyosis who have received prolonged down‐regulation

  • Only FET is planned, e.g. women receiving ovarian stimulation regimens that may adversely impact the endometrium
Interventions Intervention: fresh ET will not be undertaken in this group. Embryos will be frozen by vitrification or slow freezing at cleavage or blastocyst stage according to standard agreed local protocols. Women will be contacted after 4 weeks and arrangements made for FET.
Control: women allocated to the control arm will either undergo fresh ET at cleavage stage or extended culture and transfer at blastocyst stage according to local policy. A maximum of 2 embryos or blastocysts will be replaced according to the standard protocol under transabdominal ultrasound guidance. Luteal‐phase support is given according to local protocols.
Outcomes

  • cLBR: within 6 months of ovarian stimulation from the fresh and frozen‐thawed ET

  • Live birth: a baby born alive after 20 weeks' gestation

  • Miscarriage: miscarriage before 20 weeks' gestation

  • Clinical pregnancy: presence of at least 1 gestational sac on ultrasound at 6 weeks

  • Ovarian hyperstimulation: classified according to Royal College of Obstetrics and Gynaecology in the United Kingdom

  • Complications of pregnancy
Starting date October 2015
Contact information Ernest HY Ng: nghye@hku.hk
Notes clinicaltrials.gov/ct2/show/record/NCT02570386