1. HOW MANY DOES IT TAKE? ACHIEVEMENT OF EUPLOID BLASTOCYST (BL) AS THE PRIMARY PREDICTOR OF LIVE BIRTH (LB) IN OOCYTE CRYOPRESERVATION (OC)
Shannon DeVore MD, Sarah Druckenmiller MD, James A. Grifo MD PhD, Mary Elizabeth Fino MD, Kara N. Goldman MD, Nicole Noyes MD New York University Langone Fertility Center
OBJECTIVE
Current data suggests that LB following transfer of a euploid embryo (EE) is independent of age or type of ART treatment. At our center, we have performed >3,000 independent cycles of both OC and trophectoderm biopsy-preimplantation genetic screening (TEBX-PGS). We now use TEBX-PGS in conjunction with autologous OC thaw (AOCT) cycles. From our novel data, we estimated the no. of MII oocytes required to achieve a LB at different ages.
Oocyte development and ploidy status following AOCT+TEBX-PGS by age
Age (y)
25-34
35-37
38-40
Total N 23 61
118
202
Mean age (y)
30.7 ± 2.9
36.5 ± 0.7
38.9 ± 0.8
37.2 ± 2.86
Oocytes Retrieved
574
1045
1601
3220
MII thawed
385
698
1088
2171
MII survived
329
558
952
1839
2PN fertilized
255
424
693
1372
Blastocysts (BL)
124
215
353
692
BL biopsied
110
186
279
575
Euploid 48 60 84
192
Abnormal (Mosaic + Aneuploid) 59
122
193
374
No. MII to achieve euploid 8
(385/48) 12
(698/60) 13
(1088/84)
No. MII to achieve LB 14
(8/0.582) 20
(12/0.582) 22
(13/0.582)
Pregnancy outcomes after euploid embryo transfers
Age (y)
25-34
35-37
38-40
Total
Embryos transferred 13 25 53 91
Embryos implanted 6 17 35 58
Spontaneous/elective Ab 1 4 5
Babies born (BB) 15 23 42
Ongoing (ONG) 2 8 11
LB rate
38.5%
(5/13)
68%
(17/25)
58.5%
(31/53)
58.2% (53/91)
DESIGN
Retrospective study and theoretical model
CONCLUSIONS
EE have a relatively uniform efficiency and therefore, achievement of an EE after OC, thaw, and fertilization can help to estimate the theoretical no. of cryopreserved MII oocytes required to achieve a LB. One criticism of OC is that it provides women with a false sense of security; because of varying cycle outcomes, OC cannot guarantee future birth. Many studies on OC predicted birth probabilities are limited by lack of AOCT data and use a subset of the IVF population as a surrogate for OC patients, thus limiting their applicability. Our findings serve as a counseling tool by providing women with realistic expectations of OC outcomes at our center. LB rate per EE in the present study is less than that of IVF at our center (62.3%), possibly due to sample size versus a detrimental effect of double cryopreservation process. Further investigation is needed to determine if this difference is significant.
MATERIALS AND METHODS
Data from 152 patients (202 retrievals, 167 thaws) who underwent AOCT with intended TEBX-PGS aged 25-40y were reviewed. To calculate the no. of MII oocytes needed to achieve one EE the following data were assessed: total no. of surviving MII oocytes, 2-pronuclear (2PN) fertilization, development to BL, BL achieving quality for TEBX, and BL ploidy status after TEBX-PGS. Embryos were classified as euploid or abnormal, the latter included both mosaic and aneuploid embryos. The no. of MII oocytes needed to achieve one EE was calculated as no. MII thawed/EE. Because combining these technologies is relatively new, many pregnancies are currently ongoing (ONG). Thus LB rate included ONG pregnancies and babies born (BB), calculated as total no. ONG+BB/EE transferred. The theoretical no. of MII oocytes needed for one LB was then calculated as no. thawed MII needed to achieve one EE/LB rate per EE.
REFERENCES
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RESULTS
18.9%
See tables. Of the 1,839 MII oocytes that survived, 2PN fertilization rate was 75% and of those, 50% formed BL. 83% of BL were suitable for TEBX. These outcomes are subdivided by age in the graph. The no. of MII oocytes needed to achieve one EE was 8, 12, and 13 for age groups of 25-34y, 35-37y, and 38-40y; LB rate per EE was 58% across all ages. Thus, the no. of MII calculated to achieve one LB was 14, 20, and 22 in the age groups, respectively.