Clinical Pregnancy After Single Embryo Transfer Clinical Trial
Official title:
Time Lapse Embryo Monitoring Versus Standard Embryo Monitoring for Selection for Single Blastocyst Transfer
A multiple pregnancy is an undesired outcome of assisted reproduction. Current embryo selection technologies are inefficient in identifying the embryo with the highest implantation potential. Time lapse (TL) embryo monitoring provides additional information about embryo development and therefore may aid embryo selection. The investigators aim is to study whether TL monitoring is superior to traditional embryo observation when a single blastocyst is selected for transfer (ET).
Prospective RCT comparing two embryo selection methods (TL algorithm vs standard morphology
based) for SET. Infertile couples scheduled to undergo IVF or intracytoplasmic sperm
injection (ICSI) and met the inclusion-exclusion criteria were enrolled. Randomization to
Groups 1 or 2 was performed prior to the start of stimulation. Randomization was carried out
in blocks of two, by selecting TL or control assignments from closed, opaque envelopes.
Patients were blinded to allocation. Standard luteal long (Suprefact, Sanofi Aventis) and
flexible gonadotropin-releasing hormone (GnRH) antagonist (Cetrotide, Merck Serono) protocols
and recombinant FSH(Gonal-f, Merck Serono) were used for stimulation. Embryos were placed
into individual wells of a 9-well Primo Vision culture dish (Vitrolife AB, Sweden) on day 1
of culture, after checking for fertilization. Out of incubator handling was same in the
groups;: day 1: fertilization check; day 3: culture medium change; day 5: transfer. On days 3
and 5, the embryos were morphologically assessed under an inverted microscope. Embryos in TL
group were imaged at 10-minute intervals. The Primo Vision software was used for the analysis
of TL images. The first appearance of the 2, 3, 4 and 5 cell stages (t2, t3, t4 and t5,
respectively) were annotated. Timing of the kinetic events was calculated from the time of
the fertilization (t0). (for TL parameter definitions see supplement) There were no
adjustments of the kinetic events depending on the method of fertilization. Blastocyst
morphology was assessed using the Gardner score. Fragmentation was assessed when it reached
the highest grade in the sequence of the TL images. Cytoplasmic abnormalities (vacuoles) were
also recorded. The TL reference ranges were defined and fixed before the start of the
recruitment, Embryos in the control group were selected based on actual morphology. The
primary end point was pregnancy rate (PR; rise in β human chorionic gonadotropin [hCG]) per
patient based on intention to treat. Further endpoints were ongoing pregnancy rate (OPR;
pregnancy that progresses beyond 12 weeks gestation), pregnancy loss (loss of pregnancy after
an initial rise in βhCG up to 12 weeks gestation), live birth rate (LBR), gestational age
(GA) at delivery and birth weight of the offspring.
When calculating sample size we assumed a 13% increase in pregnancy rate from an expected 42%
to 55%. We planned to run the study with 1:1 ratio between the groups and do one interim
monitoring with 0.1 information fraction. Using two-sided test and Pocock boundaries for
estimation, 282 patients in each group was calculated (power of 80%, p of 5%). Assuming a 10%
dropout rate we needed to enroll 620 patients.
Based on the results of the interim monitoring (61 cases in two arms) the pregnancy rate in
the TL group was 15% higher than in controls (58.3% vs. 44.0%). Assuming 58% pregnancy rate
in the TL group and 44% in controls, a sample size of 210 per group, was needed to achieve a
power of 80%, at a significance level of 5%. Assuming 10% dropout rate a total sample of size
of 462 patients were needed.
The groups were compared based on maximum likelihood estimation principles. We hypothesized
and then showed that the patients in the treatment arms were similar at baseline, on average,
with respect to variables that might influence outcome. Chi-square tests, likelihood-ratio
tests and exact tests were used for the analysis of categorical variables. Continuous
variables were compared using independent group t-test and. analysis of variance. Normality
and homogeneity of variances were examined.
At the interim analysis of the trial the primary endpoint (pregnancy rate) between TL and
control group was compared with Fisher's exact test. After closing the trial the primary
endpoint (pregnancy rate) among the groups was compared with Fisher's exact test. Bonferroni
correction was used for the p-value at the end of the trial. All other p-values were
considered exploratory in nature. During the analyses the extent and distribution of missing
data were also examined. No imputations were made for missing data.
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