This study evaluates which transfer strategy will result in a higher probability of pregnancy in patients whose single best day 5 embryo resulting from an IVF cycle is classified as expansion grade \<4 by Gardner and Schoolcraft classification. All cycles will be cultured to day 6 and half the patients will undergo a fresh embryo transfer and the other half a frozen embryo transfer.
A lack of established markers for predicting blastocyst development increases the risk of having no embryos or embryos not-fully expanded available for transfer. Slower but non-arrested embryos are frequently found to have progressed to blastocyst stage by the time of a day 6 transfer. In the absence of a receptive endometrium, embryo selection for fresh transfer may be futile, and cryopreservation could be a better option. The objective is to determine which transfer strategy will result in a higher probability of pregnancy in patients whose single best day 5 embryo resulting from an IVF cycle is classified as expansion grade \<4 by Gardner and Schoolcraft classification. The investigators hypothesize that in bad prognosis patients with slow-developing blastocysts, vitrified-warmed embryo transfer will result in higher implantation, clinical and ongoing pregnancy and live birth rates than fresh embryo transfer.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
2
Patient's embryos are cultured to day 6, vitrified and transferred in a cryo-synthetic cycle
Institut Universitari Dexeus
Barcelona, Spain
Clinical Pregnancy Rate
Proportion of patients with the presence of a gestational sac seen by transvaginal ultrasonography 20 days after the embryo transfer
Time frame: 20 days after date of embryo transfer
Biochemical Pregnancy Rate
Proportion of patients with the detection of β-hCG level ≥5 mIU/mL 9 days after the embryo transfer
Time frame: 9 days after date of embryo transfer
Live Birth Rate
Proportion of patients which deliver a live infant after 24 weeks of gestation
Time frame: 24 weeks after the embryo transfer
Miscarriage Rate
Proportion of patients with a pregnancy loss following a positive pregnancy test and/or detectable gestacional sac
Time frame: 14 weeks after the embryo transfer
Cryopreservation-thaw rate
Proportion of vitrified blastocysts which survive the re-warming
Time frame: 1 day after the thawing procedure
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