Patients
This observational, retrospective, multicenter study evaluated ART
results from couples with RIF between 2013 and 2018 using data from 17
IVIRMA clinics in Europe. Infertile patients between 18 to 45 years old
at the first transfer who experienced RIF after repeated ART with their
own or donated oocytes had a minimum of three embryos transferred in
different single embryo transfers. Patients with lacked any evidence of
prior implantation events, including previous births, voluntary
interruptions of pregnancy, or clinical miscarriages were included in
the study. Patients with an abnormal karyotype such as translocation or
an inversion carrier and with thrombophilia, either congenital or
acquired, were excluded. Patients presenting severe metabolic or
endocrine disorders and patients with atrophic endometrium were not
included in the study. Submucous myomas or polyps, previous ET with high
difficulty, and/or bleeding without previous hysteroscopy correction
were excluded23.
Only embryos of good quality were transferred and day-5 embryos
(blastocysts) were graded according to expansion and quality of the
inner cell mass and trophoectoderm32. Patients who
failed to achieve a pregnancy after transfer of three to five good
quality embryos transferred in single embryo transfers were considered
RIF. We have previously observed that 94.9% of patients with three
embryos transferred achieve clinical pregnancy33, so
we compared patients who had at least three embryos transferred with
patients who had a least five embryos transferred.
A moderate RIF (M-RIF) group consisted of patients who first received at
least three transferred in single embryo transfer (SET) without
achieving implantation and without having received PGT-A or ERA.
Subsequent ETs were categorized depending on the treatment received
(Figure 1). Severe RIF (S-RIF) patients undergone five transferred
embryos summed across consecutive cycles without ERA or PGT-A testing.
All subsequent ET were categorized after ERA, PGT-A, or both. Patients
who underwent frozen ET had either natural or hormonal cycles.