DAY 6 BLASTOCYST TRANSFERS INCREASE THE PREGNANCY, IMPLANTATION AND LIVE BIRTH RATES COMPARED TO

DAY 5 BLASTOCYST TRANSFERS IN HUMAN IVF-ETL.K. Smith, E.H. Roots and M.J. Odom Dorsett

The Centre for Reproductive Medicine, Lubbock, TX

IntroductionRecent advances in ART have made it possible to routinely culture

human embryos to the blastocyst stage. Blastocyst culture and transfer

has been reported to increase pregnancy and implantation rates and to

reduce the risk of higher order multiple pregnancies in human IVF-ET

(1-4). Currently, blastocyst transfers are performed primarily on Day 5

of embryo culture. Our laboratory has investigated the possibility that

extending the transfer time to Day 6 for all IVF cases might increase

pregnancy and implantation rates further, by increasing the efficacy

of embryo selection.

ObjectiveThe objective of this study was to determine if extending embryo

transfer time to Day 6 would increase pregnancy and implantation

rates.

DesignA four-year retrospective analysis of all IVF cases with Day 5 or

Day 6 embryo transfers from April 15, 1998 to December 31, 2001.

Materials/MethodsBlastocyst culture was performed on all IVF cases. Oocytes were

co-incubated with 200,000 motile sperm/mL in 100 µL drops of S1

or G1.2 media (Vitrolife) under mineral oil (Squibb). All cultures

were performed in a 37ºC incubator with 5% CO2. Denuding and

fertilization checks were performed at 18 hrs. Embryos were

washed and moved to 30-100 µL drops of S1 or G1.2 media

under mineral oil and cultured until Day 3. The embryos

were then washed and transferred to 30-100 µL drops of S2

or G2.2 media under mineral oil and cultured until Day 5

or Day 6. Blastocyst transfers were performed on Day 5 or

Day 6 with an 18 cm Wallace transfer catheter. The transfer

day was the first day (Day 5 or Day 6) in which the embryologist

could select the best 2-3 blastocysts. Only IVF cases with 1blastocyst by Day 5 were included in the study. All IVF cases

that utilized oocyte donors or gestational surrogates were

excluded from the study. IVF-ICSI was performed on ~10%

of the cases. Statistical analysis of the data was performed

using Chi square or Student t-tests where appropriate.

ResultsTable 1: Summary of IVF Cases

n % of Cycles

--------------------------------------------------------

Cycles 467

Retrievals 404 86.5%

Transfers 338 72.4%

ICSI 44 9.4%

Cryopreservation 107 22.9%

Table 2: Analysis of IVF Cases

Day 5 Blastocysts Day 5 Blastocysts

Day 5 Transfers Day 6 Transfers

--------------------------------------------------------------------------------

Age 32.2 5.1 31.9 4.0

# Prior IVF Cycles 0.7 1.0 0.7 1.2

# Oocytes Retrieved 11.8 4.7 11.5 4.4

% Fertilization 69.2% 68.5%

% Cleavage 84.9% 86.6%

% Blastulation 40.7% 43.0%

# Blastocysts Transferred 2.4 0.7 2.0 0.9

Table 3: Day 5 vs Day 6 Blastocyst Transfers

Day 5 Blastocysts Day 5 Blastocysts

Day 5 Transfers Day 6 Transfers

------------------------------------------------------------------------------------

# Transfers 82 157

Positive ßhCG/Transfer 59.8% (49/82) 77.1% (121/157)*

Positive US/Transfer 47.6% (39/82) 63.7% (100/157)*

Live Birth/Transfer 43.9% (36/82) 62.4% (98/157)*

% Implantation 29.9% (60/201) 48.5% (150/309)*

* Results differ from Day 5 transfers at P < 0.01 Chi square.

Results are expressed as the percent of blastocysts transferred on Day 6 that would have been selectedfor transfer on Day 5 or Day 3.* Results differ from Day 6 at p < 0.01 Chi square.

ConclusionsDay 6 blastocyst transfers increased the pregnancy,implantation and live birth rates compared to Day 5blastocyst transfers in IVF-ET cases that presented 1blastocyst on Day 5. These results suggest that blastocysttransfers should be performed on Day 6 for optimal results.The implantation rates of Day 6 blastocyst transferssuggests that acceptable pregnancy rates may beachieved using single embryo transfers.

References1. Gardner DK, Vella P, Lane M, Wagley L, Schlenker T, Schoolcraft WB. Culture and transfer of human blastocysts increases implantation rates and reduces the need for multiple embryo transfers. Fertil Steril 1998;69:84-88.2. Gardner DK, Schoolcraft WB, Wagley L, Schlenker T, Stevens J, Hesla J. A prospective randomized trial of blastocyst culture and transfer in in-vitro fertilization. Hum Reprod 1998;13:3434-3440.3. Behr B, Pool TB, Milki AA, Moore D, Gebhardt J, Dasig D. Preliminary clinical experience with human blastocyst development in vitro without co-culture. Hum Reprod 1999;14:454-457.4. Marek D, Langley M, Gardner DK, Confer N, Doody KM, Doody KJ. Introduction of blastocyst culture and transfer for all patients in an in vitro fertilization program. Fertil Steril 1999;72:1035-1040.

Day 5 Blastocysts Day 6 Blastocysts

Graph 1: Transferred Day 6 Blastocysts Retrospectively

Selected

100%

73.2% *

46.1% *

0

20

40

60

80

100

120

Day 6 Day 5 Day 3

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