1. The Debate: Fresh vs Frozen Transfer The Cold, Hard Truth
Amber R. Cooper, MD, MSCI
Assistant Professor
Division of Reproductive Endocrinology & Infertility Department of Obstetrics & Gynecology

2. Disclosures Scientific advisory board Celmatix
Grant funding: K12HD , UL1TR000488
Industry research support: Beckman Coulter, Inc

3. SHE

4. What we DO agree on….
Frozen embryo transfers are an important part of successful IVF clinics
Vitrification has improved freezing success with both embryos and oocytes
Endometrial-Embryo synchrony is very important for successful implantation
Absolute risks of both approaches are overall quite small

5. FRESH OR FROZEN EMBRYO TRANSFER???
Where we differ…
What is the best first line approach…
FRESH OR FROZEN EMBRYO TRANSFER???

6. What is the best FET cycle approach?
Timing of embryo cryopreservation?
2PN, CD2/3, CD5/6
Slow-freezing vs vitrification?
Transfer in a medicated or natural cycle?
Use of leuprolide?
Recommended number of embryos to transfer
Culture media?
Frequency of SET?
Timing of progesterone start?

7. Slow-freezing vs Vitrification: Perinatal risk
No perinatal risks D3 embryos
Liu SY, Hum Reprod 2013
Shi W, Fertil Steril 2012
No perinatal risks D5/6 embryos
Takahashi K, Fertil Steril 2005 (no diff congenital defects)
Wikland M, Hum Reprod 2010 (vit blastocyst vs D3 slow)
The majority of perinatal risk data is from slow freezing and cleavage stage embryos
About 4000 babies first couple studies

8. Is extended embryo culture ideal?
Yes, for improving implantation and pregnancy rates, and minimizing higher order multiples
BUT D5/6 transfer as compared to D3 increases the risk of Preterm Delivery by 30-40%
US: Kalra S et al. Obstet Gynecol 2012; SART data, 69,039 LB, fresh ET
Canada: Dar S et al. Hum Reprod 2013; 12,712 LB
Sweden: Kallen B et al. Fertil Steril 2010; 13,873 LB
D5/6 vs D3 also with increased absolute birthweight and incidence of LGA
China: Zhu J et al. Hum Reprod 2014; 2,929 singletons, fresh,
Makinen S, Hum Reprod 2013
2/3 CD3; SART
Fresh, no diff in LBW %
China study-difference pt bias, initial tx d3 tfr; day 5/6 if past implantation failure

9. Fresh vs Frozen: Perinatal risks
Numerous cohort and meta analyses suggest outcomes better with FET as compared to fresh (SGA, LBW, PTD) but still worst than spontaneous
Pelkonen 2010, Pinborg 2010, Sazonova 2013, Wennerholm 2009, Maheshwari 2012, Pinborg 2012
No difference in birth defects in fresh vs FET
Meta-analysis: Maheshwari A, Fertil Steril 2012; OR 1.1 ( )
Hansen M Obstet Gynecol 2012, Davies NEJM 2012, Jalliday JL Hum Reprod 2010
-most data with slow-freezing
SGA, LBW and PTD often better with FET

10. Fresh vs Frozen: Perinatal risks
BUT, Numerous studies suggest increased risk of LGA and macrosomia with FET vs fresh or spontaneous
Pelkonen 2010, Pinborg 2010, Sazonova 2012
Wennerholm 2013: Nordic cohort, CoNARTaS group: 6647 FET, fresh, spontaneous singletons-increased risk LGA, macrosomia, and perinatal mortality (49% increase)
Wennerholm 2013, most slow freeze, day 2, txfr natural cycle
Perinatal risk: stillbirth> or equal 28 wks to neonatal death
Adj for mat age, parity, year of birth, gender, country

11. Perinatal risks: LGA
Is the epigenetic regulation of the placenta altered?
Nelissen 2011, Vergouw 2012
Denmark study FET vs fresh, sibling subgroup 2-4 fold higher incidence of LGA in FET siblings; Pinborg 2014
Is it in vitro culture media/methods?
Young 1998 (cattle/sheep), Dumoulin 2010, Nelissen 2012
In mice imprinting changes with in vitro culture more pronounced with freezing; Market-Velker 2010
Is it the extended culture issue?
Makinen 2013
An endometrial synchrony issue?
Wilmut I 1981; D3 sheep embryos transferred to advanced lining caused 40% increased fetal size
Pinborg 2014, >99% FET slow frozen CD2

12. Perinatal risks: LGA More recent vitrification data
Kato et al, 2012; Japan ( cycles)
4092 vitrified SET vs 2531 fresh SET
Transfers D2 and D5
LGA crude OR 1.51 ( ), aOR 1.23 ( ) after adjustments including blastocyst culture
D3 fresh vs D3 vitrified-no difference perinatal outcomes in general
Liu SY et al 2013, Shi W et al 2012

13. And for SGA…?
Fresh may have increased risk of SGA as compared to frozen
Helmerhorst 2004, Jackson 2004, McDonald 2009
Though underlying infertility etiology and supraphysiologic levels of hormone may be more to blame…
Cooper A 2011 Fertil Steril
1200 vs 460 F vs I; infertile had smaller neonates and more LBW than fertile at birth and in the first trimester; Within infertiliy subgroups no differences

14. Wash U fresh vs frozen sibling study
CRL did not differ between the groups (difference 1.3 mm, 95% CI -1.1 to 3.7)
No difference in birthweight between fresh & FET singleton siblings (difference 129 grams, 95% CI -155 to 412)
FET singletons had a significantly shorter gestation than their fresh IVF siblings, delivering on average 14 days earlier (95% CI 3-25 days; p=0.01)
Fresh (n=23)
Frozen (n=23)
p value
Crown Rump Length
(millimeters)
8.3 ± .8
7.3 ± 1.0
p =.86
Birthweight
(grams)
3280 ± 100
3248 ± 158
p = .87
Gestational Age at Birth
(days)
252 ± 3
241 ± 4
p = .01
O’Neill KE and Cooper AR. Fertil Steril 2010; 94(4); S19
Primary outcome were size (measured in the 1st trimester with CRL in mm and at birth with weight in grams) and gestational length measured in days.

15. Perinatal risks: Neurodevelopment?
Swedish study, births (2.5 million infants, 1.2% by IVF)
IVF vs spont, ICSI vs no ISCI, fresh vs frozen
No increased risk of autism in fresh vs frozen, ICSI vs no, only with surgically extracted sperm
aRR MR if fresh + ICSI 1.47 ( ), ICSI + frozen + preterm birth 3.47 ( )
When adjusting for singletons only ICSI + frozen remained significant for MR; 2.36 ( )
Sandin S et al, JAMA 2013
Rate per 100,000 person years. AR small
Evolving theories of epigenetics in brain development
Incidence of autism and MR 1-1.5%
Risk of MR in IVF vs spont disappeared w singletons only
Blastocyst data available for 2002+, subanalysis no difference though smaller numbers

16. The forest through the trees…
Subtle differences at birth may
have health consequences that
manifest as adults
Barker hypothesis
Grace and Sinclair 2009 (animal review)
Ceelen M, 2008; higher BP/FBG
8-18 y/o ART kids
Hart and Norman 2013; higher BP/FBG in ART adults
We need to sort out the underlying etiologies

17. An additive (or masking) effect?
Ovarian Stimulation
…In subtle epigenetic effects…?
In vitro maturation
Extended Culture
…Is cryo just one more piece…?
Cryo-
Preservation

18. Other issues with FET Additional cost Disposition of excess embryos
Optimal length of storage for vitrification?