The Debate: Fresh vs Frozen Transfer

The Cold, Hard Truth

Amber R. Cooper, MD, MSCI

Assistant ProfessorDivision of Reproductive Endocrinology & Infertility

Department of Obstetrics & Gynecology

Disclosures

• Scientific advisory board Celmatix

• Grant funding: K12HD063086-01, UL1TR000488• Industry research support: Beckman Coulter, Inc

SHE

What we DO agree on….

1. Frozen embryo transfers are an important part of successful IVF clinics

2. Vitrification has improved freezing success with both embryos and oocytes

3. Endometrial-Embryo synchrony is very important for successful implantation

4. Absolute risks of both approaches are overall quite small

Where we differ…

• What is the best first line approach…

FRESH OR FROZEN EMBRYO TRANSFER???

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?

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

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, 2009-2012 – Makinen S, Hum Reprod 2013

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 (0.8-1.4)• Hansen M Obstet Gynecol 2012, Davies NEJM 2012, Jalliday JL Hum Reprod 2010

-most data with slow-freezing

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, 42242

fresh, 288542 spontaneous singletons-increased risk LGA, macrosomia, and perinatal mortality (49% increase)

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

Perinatal risks: LGA• More recent vitrification data

– Kato et al, 2012; Japan (2006-2008 cycles)– 4092 vitrified SET vs 2531 fresh SET – Transfers D2 and D5– LGA crude OR 1.51 (1.32-1.74), aOR 1.23 (0.88-1.72) 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

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

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

Perinatal risks: Neurodevelopment?

• Swedish study, births 1982-2007 (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 (1.03-2.09), ICSI + frozen +

preterm birth 3.47 (1.22-9.90)• When adjusting for singletons only ICSI + frozen

remained significant for MR; 2.36 (1.04-5.36)

Sandin S et al, JAMA 2013

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

An additive (or masking) effect?

Ovarian Stimulation

In vitro maturation

Extended Culture

Cryo-Preservation

…In subtle epigenetic effects…?

…Is cryo just one more piece…?

Other issues with FET

• Additional cost• Disposition of excess embryos• Optimal length of storage for vitrification?