estradiol (E2) and sex hormone-binding globulin (SHBG). Free E2 was cal-culated using SHBG and the E2/ E1S ratio calculated. A student’s T test,Mann-Whitney test, and Wilcoxon rank sum test were used to determinestatistical differences.

RESULT(S): 22 women with BC were included in this analysis. 12/22 re-ceived Tamoxifen daily throughout stimulation (Ant + Tam) and 10/22 un-derwent standard antagonist protocols (Ant only). The mean age (35.9�3.9vs. 39�3.0) and BMI (22.7�2.5 vs. 24.6�2.1) in the Ant + Tam and Antonly groups were not significantly different. Baseline E2, E1S, and E2/ E1Swere similar in both groups. There was a progressive increase in all estrogensfrom baseline to the peri-ovulatory phase in all patients. The total peri-ovu-latory E2 was significantly higher in the Ant + Tam group compared with theAnt only group (3218 vs. 1910 pg/mL, p¼0.47), likely due to the greaternumber of follicles (21.5�6.6 vs. 13.7�7.8) and oocytes retrieved(17.6�7.3 vs. 11.8�8.9). However, there was no significant difference infree E2 levels (53.1 vs. 29.9 pg/mL, p>.05), and E1S levels (60.1 vs. 42.9ng/mL, p¼ .03) were significantly higher in the Ant + Tam groupcompared with the Ant only group. There was a trend toward lower E2/E1S ratio (0.06 vs. 0.09, p¼0.078) in the Ant + Tam group.

CONCLUSION(S): This is the first study to our knowledge to describe Emetabolism at supraphysiologic levels in BC patients receiving Tamoxifen asan adjunct to COH. Greater conversion of active E2 to inactive E1S in the Ta-moxifen group may confer a protective effect in E metabolism. These find-ings support the theory that concurrent use of Tamoxifen reduces the riskof COH in BC patients, not only by direct receptor blockade, but also by po-tentially altering E metabolism.

SUPPORT: None.

P-56

Does Prior Success Predict Future Performance in FET Cycles? LouisN. Weckstein, M.D., Ariana Weckstein, Bethany Layport, Kristen Ivani,Ph.D., Nancy Huen, M.S., E.L.D., Mary D. Hinckley, M.D. ReproductiveScience Center of the San Francisco Bay Area, San Ramon, CA.

BACKGROUND: With the advent of improved cryopreservation successcoupledwith increasing utilization of elective single embryo transfers, frozenembryo transfers (FET) are increasingly being performed. Understanding thelikelihood of success based upon prior outcomewill help physicians in coun-seling patients on the ideal number of embryos to transfer.

OBJECTIVE(S): We hypothesized that patients with successful IVF cy-cles would have higher pregnancy rates in subsequent FET cycles comparedwith patients not achieving pregnancy in their fresh IVF cycle.

METHOD(S): Retrospective review of 352 FET cycles (first FET cycleonly following fresh IVF cycle) when only one or two embryos were trans-ferred, from January 2011 – June 2012. Chi-Squared analysis was performedusing OpenEpi.1

RESULT(S):

Clinical

F

ERTILITY

# FETs

& ST

Preg from FET

ERILITY�

eSET FETs

All ETs 1 Emb ETs 2 Emb

Pos Fresh IVF

143

Own Eggs

119 53/119 (44.5%) 12/29 (41.3%) 26/66 (39.4%) 34/53 (64.2%)

Donor Eggs

24 10/24 (41.6%) 5/10 (50%) 5/11 (45.5%) 5/13 (38.5%)

Neg Fresh IVF

209

Own Eggs

176 96/176 (54.5%) 7/24 (29.2%) 12/47 (25.5%) 84/149 (56.4%)

Donor Eggs

33 12/33 (36.4%) 4/9 (44.4%) 6/13 (46.2%) 6/20 (30%)

Patients using their own eggs who had a negative fresh IVF cycle hada higher clinical pregnancy rate in their subsequent FET cycle (96/176,54.5%) compared with patients with a successful fresh IVF cycle (53/119,44.5%, p<0.046).

There was no significant difference in the FET pregnancy rate in OocyteDonation (OD) recipients after successful fresh OD cycles (10/24, 41.6%)compared with unsuccessful fresh OD cycles (12/33, 36.4%).

There was a non-significant trend toward a higher clinical pregnancy ratein eSET FETs when comparing successful (12/29, 41.3%) with unsuccessful(7/24, 29.2%) fresh cycle patients.

Therewas no significant difference between clinical pregnancy rates in thetwo groups when transferring two embryos in FET cycles. There was no sig-nificant difference in multiple pregnancy rates. When transferring two

embryos in FET cycles, 44.4% of pregnancies were multiple pregnancies(3 triplets).

Multiple Pregnancies with 2 ET in FET

FET after Pos Fresh IVF

Own Eggs

12/34 (35.3%)

Donor Eggs

2/5 (40%)

FET after Neg Fresh IVF

Own Eggs

28/56 (50%)

Donor Eggs

2/6 (33.3%)

There was a significantly higher clinical pregnancy rate in FET cycles inboth groups using their own eggs when two embryos were transferred com-pared with one (overall 59% vs 36%, p¼0.001).CONCLUSION(S): Contrary to our hypothesis, in subsequent FET cycles,

patients who had a successful fresh IVF cycle do not have a higher pregnancyrate, or higher multiple pregnancy rate than patients not achieving a pregnancyin their fresh IVF cycle. Clinical pregnancy rates for FET cycles in both groups(successful fresh versus unsuccessful fresh) were higher when two versus oneembryo was transferred, but with a 44.4% multiple pregnancy rate. Patientswho did not get pregnant in the fresh IVF cycle have at least as good of a chanceof pregnancy in the subsequent FET cycle with similar multiple pregnancyrates. This information is useful in counseling patients going through FET cy-cles, and helpful in deciding whether to thaw and transfer one or two embryos.BIBLIOGRAPHY:1. Dean AG, Sullivan KM, Soe MM OpenEpi: Open Source Epidemio-

logic Statistics for Public Health, Version 2.3.1. www.OpenEpi.com,updated 2011/23/06, accessed 2012/11/14.

P-57

Dynamic Analysis of Relationship between Timing of Syngamy andHuman Embryonic Development Using Time-Lapse Cinemato-graphy. Minako Ueda. MIO Fertility Clinic, Reproductive Centre, Yo-nago, Japan.

BACKGROUND: In 2011, Istanbul consensus workshop has proposedthat the assessment of syngamy (24 h post insemination) is very sensitive pre-dictors for embryonic quality (RBMOnline, 2011). However, the value as in-dependent predictor of outcome is still unclear.OBJECTIVE(S):We have reported several novel aspects of human embry-

onic development in vitro using time-lapse cinematography (TLC). In thisstudy, we analyzed the relationship between timing of syngamy and humanembryonic development using TLC.MATERIALS AND METHOD(S): We have developed a system of TLC,

which is described elsewhere (AJOG, 2008). Culture temperature was main-tained at 37.0� 0.2�C and pH at 7.37� 0.05 by controlling CO2 flow. Afterc-IVF or ICSI procedure, oocytes donated (n¼203) were analyzed for TLC.In c-IVF, the cumulus cells were gently removed at one hour post insemina-tion, so as not to damage the tail of the sperm that had penetrated the zonapellucida, and transferred into culture media for TLC. In ICSI, oocyteswere commenced TLC after the procedure.RESULT(S): Of 203 oocytes, normally fertilized embryos were 128 (c-

IVF: 50, ICSI: 78) and the rest were abnormal fertilization (n¼13), undetect-able (n¼35) and unfertilized (n¼27). In normal fertilized embryos, the timerequired from the extrusion of 2nd polar body to syngamy in c-IVF and ICSIwere 21.2 � 3.6 hours and 20.8 � 3.6 hours, respectively. The time requiredfor syngamy in good quality embryos (GQE) was 20.0 � 3.3 hours and inpoor quality embryos (PQE) was 22.1 � 4.3 hours, respectively and the dif-ference was significant (P<0.05). In addition, the time required for syngamyin abnormally fertilized embryos was 25.1� 6.3 which was obviously de-layed compare to normal fertilized embryos.CONCLUSION(S): Although there was no difference in the time required

for syngamy by the insemination procedures (IVF or ICSI), the time requiredfor syngamy in GQE was significantly shorter than that in PQE, suggestingthat timing of syngamy would be a useful parameter to assess the embryoquality in human embryos. Furthermore, the time required for syngamy be-tween normally and abnormally fertilized embryos was significantly differ-ent, suggesting that we could distinguish the normally fertilized embryosfrom abnormal embryos by assessment of timing of syngamy.SUPPORT: None.

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