Embryo Transfer Outcomes After Vitrification With Slush Nitrogen Compared to Liquid Nitrogen

Major Inclusion Criteria for participants:

1. Patients undergoing IVF stimulation cycle with plan for subsequent frozen embryo
transfer (FET)

2. Patients electing preimplantation genetic testing for aneuploidy (PGT-A)

3. Couples electing single embryo transfer (SET)

Major Exclusion Criteria for participants:

1. All patients who do not voluntarily give their written consent for participation

2. Under 18 years old, above 42 years old

3. BMI > 35

4. Maximum day 3 Follicle stimulating hormone (FSH) level of 12 or higher

5. Anti-mullerian hormone (AMH) level less than 1.0 g/mL, tested within previous year

6. Total basal antral follicle count less than 6 follicles

7. Failed more than one previous FET cycle

8. Use of oocyte donation

9. Use of gestational carrier

10. Presence of hydrosalpinges that communicate with endometrial cavity

11. Diagnosis of endometrial insufficiency: prior cycle with maximal endometrial
thickness ≤ 6mm, abnormal endometrial pattern (failure to attain a trilaminar
appearance), persistent endometrial fluid

12. Uncorrected uterine factor infertility (uterine anomaly, submucosal myomas, uterine
septum)

13. Single gene disorder chromosomal rearrangement requiring a more detailed embryonic
genetic analysis

14. Male partner with <100,000 total motile spermatozoa per ejaculate (donor sperm is
acceptable)

15. Use of surgical procedures to obtain sperm

16. Couples undergoing IVF for fertility preservation with no immediate plan for
subsequent FET (embryo banking)

17. Sex selection

18. Personal history of repeated pregnancy loss (two or more unexplained clinical losses
defined by presence of fetal heartbeat)