Factors useful in predicting the success of oocyte donation: a 3-year retrospective analysis.

OBJECTIVE: To establish prognostic relevance of parameters assessed in oocyte donation cycles. DESIGN: Retrospective analysis. SETTING: Large university-based donor oocyte program. PATIENT(S): All oocyte recipient cycles achieving embryo transfer from September 1995 to October 1998. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Pregnancy. RESULT(S): Recipient age and reproductive status, day 9 and 12 serum estradiol (E(2)) levels and a progesterone (P) level obtained 2 days after initiation of hormonal therapy did not correlate with pregnancy. Endometrial thickness, but not endometrial pattern, was useful in predicting pregnancy outcome. The clinical pregnancy and live-birth rate in cycles where the endometrial thickness was less than 8 mm was significantly lower when compared to cycles with an endometrial thickness > or =9 mm. Cycles where optimal quality embryos were transferred had the highest implantation (36%), clinical pregnancy (63%) and live birth (54%) rates and these rates were significantly higher than those of cycles where only poor quality embryos were available for transfer (10% implantation, 17% clinical pregnancy, and 8% live birth rates, respectively; P<.05). CONCLUSION(S): The most reliable predictive factors for pregnancy in oocyte donation cycles are the quality of the embryos transferred and the recipient's mid-cycle endometrial thickness. Recipient monitoring should minimally include ultrasound assessment of endometrial thickness.     

Controlled ovarian hyperstimulation does not adversely affect endometrial receptivity in in vitro fertilization cycles

OBJECTIVE: To determine whether exposure of developing endometrium to supraphysiologic E2 levels during controlled ovarian hyperstimulation (COH) in IVF cycles inhibits endometrial receptivity. DESIGN: Retrospective analysis of IVF-ET and ovum donation data. SETTING: Tertiary-care teaching hospital. PATIENT(S): Four hundred ten patients <33 years of age undergoing IVF-ET and 181 anonymous ovum donors (<33 years of age) and their associated ovum recipients. MAIN OUTCOME MEASURE(S): Implantation, pregnancy, and delivery rates. RESULT(S): Ovarian response to COH (duration of stimulation, peak E2 level, area under the curve for E2 exposure, and number of oocytes retrieved) was similar for IVF-ET patients and ovum donors. Donors were younger than IVF-ET patients (mean age, 27.5 +/- 0.2 years vs. 30.4 +/- 0.1 years). A similar number of embryos with similar number of blastomeres were transferred in IVF-ET patients and ovum recipients. The fragmentation rate at time of transfer differed slightly between groups (5.2 +/- 0.2% vs. 4.3 +/- 0.3%). Implantation, pregnancy, and delivery rates did not differ between IVF-ET patients and recipients of donor oocytes. CONCLUSION(S): Exposure of the developing endometrium to controlled ovarian hyperstimulation during IVF cycles does not inhibit embryo implantation or affect pregnancy and delivery rates.     

Early pregnancy losses in in vitro fertilization and oocyte donation

Objective: To evaluate prospectively the incidence of early pregnancy losses (before menstruation occurs) in IVF and ovum donation cycles.

Design: Prospective case-control study.

Setting: Tertiary care, university-associated center.

Patient(s): One hundred forty-five patients undergoing IVF and 92 undergoing oocyte donation were recruited. The control group for IVF consisted of 15 ovum donors who had no ET and were instructed to avoid intercourse. The control group for oocyte donation included 10 women undergoing a mock cycle of steroid replacement.

Intervention(s): Starting on day 6 after ET, the women were instructed to collect the first urine sample of the day every 2 days. Each patient collected six different specimens of urine (days 6, 8, 10, 12, 14, and 16 after ET for cases or the same days without ET for controls.

Main Outcome Measure(s): β-HCG was measured with a standardized microparticle enzyme immunoassay, and IVF reproductive outcome was assessed.

Result(s): For IVF, positive implantation was registered in 88 of 145 cycles of embryo replacement (60.7%). Only 30 (20.7%) resulted in viable pregnancies, whereas the remaining 58 miscarried. Forty-two of these miscarriages (72.4%) were early pregnancy losses and 13 (22.4%) were classified as clinical abortions. In ovum donation, positive implantation was recorded in 64 of 92 cycles of ET (69.6%). A total of 30 (32.6%) ended in viable pregnancies, whereas the remaining 34 (37.0%) were miscarriages. Early pregnancy loss accounted for 70.6% of pregnancy losses, whereas biochemical pregnancies and clinical abortions accounted for 11.8% and 17.6%, respectively.

Conclusion(s): Our results demonstrate that patients undergoing assisted reproductive technology have an increased rate of early pregnancy loss compared with fertile patients. In addition, these data indicate that implantation is more frequently impaired in IVF than in oocyte donation cycles, resulting in a high incidence of early pregnancy loss. This suggests that implantation may be subjected to abnormal conditions in assisted reproduction.     

Is blastocyst transfer useful as an alternative treatment for patients with multiple in vitro fertilization failures?

OBJECTIVE: To determine whether blastocyst transfer is of benefit to patients with multiple IVF failures. DESIGN: Retrospective cohort study. SETTING: The George Washington University Medical Center. PATIENT(S): Patients undergoing IVF between October 1, 1997, and November 30, 1998, who had previously undergone three or more unsuccessful IVF cycles. Patients who had at least three embryos at the 8- to 12-cell stage available on day 3 were eligible for the study. INTERVENTION(S): Patients were given the option of day 3 ET (group A) or blastocyst transfer (group B). MAIN OUTCOME MEASURE(S): Blastocyst-formation rate, clinical pregnancy rate (PR) per transfer, and implantation rate per transfer. RESULT(S): Groups A and B were similar in terms of age, the number of previous failed IVF cycles, fertilization rate, and the number of fertilized oocytes per cycle. The blastocyst-formation rate was 51.0%. Clinical pregnancy and implantation rates per transfer were statistically significantly higher in the blastocyst-transfer group. There were no multiple pregnancies after blastocyst transfer. CONCLUSION: Blastocyst transfer increases implantation rates and PRs in patients with multiple failed IVF cycles, without increasing the risk of multiple pregnancy.     

Middle to lower uterine segment embryo transfer improves implantation and pregnancy rates compared with fundal embryo transfer

OBJECTIVE: To assess differences in pregnancy and implantation rates as a function of the embryo placement. DESIGN: Prospective cohort study. SETTING: A tertiary care center. SUBJECT(S): All fresh, nondonor IVF cycles performed in 2001. INTERVENTION(S): Alteration in embryo transfer (ET) target location from the fundal region to the middle to lower uterine segment. MAIN OUTCOME MEASURE(S): Clinical pregnancy rate (sonographic sac evidence/number of transfer cycles), implantation rate (number of sacs/number of embryos transferred), patient age, peak E(2), and fertilization rate. RESULT(S): A total of 393 fundal and 273 lower to middle uterine segment ETs were performed. The pregnancy (PR), implantation, and birth rates were significantly higher after a middle to lower uterine segment ET compared with fundal ET (39.6% vs. 31.2%; 21% vs. 14%; and 34.1% vs. 26.2%, respectively). Groups did not differ regarding patient age, basal FSH, peak E(2), number of intracytoplasmic sperm injection (ICSI) cycles, fertilization rate, embryo quality, or number of embryos transferred. CONCLUSION(S): Both PR and implantation rates are favorably affected by directing embryo placement to the lower to middle uterine segment. By some unknown mechanism, it appears that this endometrial location provides a more favorable region for embryo deposition.     

Effectiveness of 2-step (consecutive) embryo transfer. Comparison with cleavage-stage transfer

OBJECTIVE: To evaluate the effectiveness of 2-step (consecutive) embryo transfer (ET), in which two cleaved embryos are transferred on day 2 (first step of ET) and a single blastocyst is transferred on day 5 (second step of ET) in comparison with conventional day 2 ET. STUDY DESIGN: Observational comparative study at different time periods. Subjects were those who had > or = 4 embryos on day 2 after oocyte retrieval. Those in the conventional group (n = 60) received conventional day 2 ET, in which 3 cleaved embryos were transferred on day 2 between January 1999 and June 2000. Those in the 2-step group (n = 124) received 2-step embryo transfer, in which 2 cleaved embryos were transferred on day 2 and a blastocyst was transferred on day 5 between September 2000 and February 2002. Patients who planned to receive 2-step ET but could not proceed to the second step of ET because of failure to produce blastocysts were included in the 2-step group. RESULTS: The ongoing pregnancy rate with 2-step ET (51.6%) was significantly higher than with conventional ET (26.7%) (P < .01). The clinical pregnancy rate and implantation rate in conventional and 2-step ET were 30.0% vs. 59.7% and 11.1% vs. 27.8%, respectively (P < .001). CONCLUSION: Two-step ET may benefit patients who can obtain a sufficient number of embryos.     

Is there any difference in pregnancy and implantation rates when nurses perform embryo transfer in an IVF-ET program?

A retrospective analysis of fresh in vitro fertilization treatment cycles and frozen embryo transfer (FET) cycles from mid-1995 to December 31, 1998, was undertaken. Nurses performed embryo transfer (ET) for government-funded cycles, whereas doctors performed ET for self-funded cycles. During the study period, fresh ET was performed in 1,165 treatment cycles. There were no significant differences in demographic data, ovarian responses and the number of embryos replaced between ET cycles performed by nurses and doctors. Pregnancy rates for ETs performed by nurses and doctors were 16.7 and 15.8% per transfer, respectively, whereas the corresponding implantation rates were 8.3 and 6.9%, respectively. Similar pregnancy and implantation rates were encountered in FET cycles whether ET was performed by nurses or doctors.     

Transabdominal ultrasound-guided embryo transfer does not increase pregnancy rates in oocyte recipients

OBJECTIVE: To determine whether transabdominal ultrasound guidance during embryo transfer (ET) is a useful tool for increasing pregnancy rates in patients undergoing oocyte donation.DESIGN: Prospective, randomized, controlled trial.SETTING: In vitro fertilization academic center.PATIENT(S): Three hundred seventy-four infertile patients undergoing oocyte donation.INTERVENTION(S): Transabdominal ultrasound-guided ET.MAIN OUTCOME MEASURE(S): We measured the pregnancy rate and implantation rate after transabdominal ultrasound-guided ET versus the rates in a control group who did not receive transabdominal ultrasound-guided ET.RESULT(S): Clear visualization at ultrasound during ET was achieved in 90.8% of the patients who had ultrasound-guided ET. A similar number of easy transfers were performed in both the ultrasound-guided and the control groups (84.5% vs. 86.6%). The pregnancy rate was comparable between the groups (59.9% ultrasound vs. 55.1% control), as was the implantation rate (30.6% ultrasound vs. 26.3% control). No differences were found in the miscarriage rate (10.7% ultrasound vs. 9.1% control) or in the multiple pregnancy rate (21.4% ultrasound vs. 22.5% control). Although all ectopic pregnancies occurred in the group that did not receive ultrasound guidance, the differences were not statistically significant (0 vs. 2.7%).CONCLUSION(S): We could not show any benefit in terms of pregnancy rate in oocyte recipients for whom ET was performed under direct transabdominal ultrasound visualization of the endometrial cavity. There was a lower ectopic pregnancy rate when ultrasound guidance was used, but this rate was not statistically significant in comparison with the pregnancy rate without ultrasound guidance.     

Monozygotic Twins and Triplets in Association with Blastocyst Transfer

PURPOSE: To compare the incidence of monozygotic twins following blastocyst versus day-3 embryo transfer (ET). METHODS: A retrospective analysis of the outcome of assisted reproductive technology (ART) cycles utilizing blastocyst ET during 1999-2000 was compared to a similar group of patients undergoing day-3 ET during 1997-1998. RESULTS: Blastocyst ET was used in 75 cycles with 2.0 +/- 2 embryos transferred. The comparison group consisted of 90 cycles with day-3 ET and 3.0 +/- 2 embryos transferred. CONCLUSIONS: High pregnancy rates are maintained with blastocyst ET even though fewer embryos are transferred. The rate of monozygotic twins is higher with blastocyst ET than with day-3 ET. This increase may partially negate the benefit of reduced high-order multiple gestations attributed to blastocyst ET.     

Embryo transfer is equally effective at cleavage stage and blastocyst stage: a randomized prospective study

OBJECTIVE: To compare the implantation and pregnancy rates after cleavage stage embryo transfer (ET) with transfer of blastocyst-stage (days 5-6) embryos. STUDY DESIGN: Prospective randomized trial at an assisted reproduction unit in a university hospital. Women with six or more follicles at the last ultrasound scan before oocyte aspiration were randomized for transfer of a maximum of two embryos after 2-3 days (n = 80) or after 5-6 days (n = 64) of culture. Embryo quality, implantation and pregnancy rates were evaluated. Statistical significance was tested with the Chi-square test and Fisher's exact test. RESULT(S): No significant difference was observed in implantation rates (21.1% versus 20.9%, respectively) and clinical pregnancy rates (36.7% versus 32.5% respectively) after blastocyst and cleavage stage transfers for the two groups. The pregnancy rate among subjects who had at least one good quality embryo transferred was 37.5% per day 2-3 ET and 60% per day 5-6 ET. CONCLUSION(S): The overall implantation and pregnancy rates after embryo transfer at cleavage stage and at blastocyst stage transfer were not statistically different. Women who had at least one good quality blastocyst (n = 25) had a high pregnancy rate (60% per ET). Blastocyst transfer is a good alternative for couples with many good quality embryos on day 2 after insemination.     

Day 2 embryo transfer (ET) and day 3 ET afford similar reproductive outcomes in the poor responder

A retrospective review of 237 initial, fresh nondonor IVF cycles in which all embryos generated during the cycle were transferred on either day 2 (n = 109) or day 3 (n = 128) were evaluated with regards to reproductive outcomes. Patients who underwent a day 2 ET had similar conception (18% vs. 16%; relative risk [RR], 1.1; 95% confidence interval [CI], 0.64-1.95), clinical pregnancy (13% vs. 16%; RR, 0.8; 95% CI, 0.44-1.55), implantation (6% vs. 7%; RR, 0.9; 95% CI, 0.50-1.68), and live-birth (10% vs. 16%; RR, 0.7; 95% CI, 0.32-1.29) rates as those who underwent a day 3 ET.     

Transfer of nonselected transferable day 3 embryos in low embryo producers

OBJECTIVE: To examine the implantation potential of embryos from assisted reproductive technology cycles with low embryo production and to assess the effects of clinical variables and embryo scores (ES) on pregnancy outcome. DESIGN: Prospective clinical study. SETTING: Assisted reproductive technology unit in a tertiary medical center. PATIENT(S): From July 1998 to December 2001, 280 cycles in 229 infertile couples produced a limited number of one, two, or three embryos 3 days after oocyte retrieval and underwent fresh embryo transfer (ET). INTERVENTION(S): Embryos with two or more blastomeres were scored and transferred. MAIN OUTCOME MEASURE(S): ES and implantation rate per ET. RESULT(S): Of 863 fresh ET cycles during the study period, 32.4% (280) were low embryo producers. Among them, there were no significant differences in average ES of individual embryos in single, dual, or triple ET or in embryos obtained from patients with low or high E2 responses, or young or old age. Embryos derived from conventional IVF had a better ES than those derived from intracytoplasmic sperm injection. The clinical pregnancy rate was strongly correlated with the cumulative ES. Implantation rates were similar among and between groups, with an average rate of 15.9%. CONCLUSION(S): Embryos of low embryo producers had an inherently low implantation potential that appeared to be unrelated to the number of embryos transferred, female age, ovarian E2 genesis, or fertilization method. The cumulative ES can serve as a predictor of pregnancy.     

Anonymous oocyte donation performed exclusively with embryos cryopreserved at the pronuclear stage

OBJECTIVE: To evaluate the clinical outcomes of patients who participated in an anonymous oocyte donation program that used embryos cryopreserved at the pronuclear stage. DESIGN: Observational study. SETTING: A tertiary care reproductive medicine unit. PATIENT(S): Anonymous oocyte donors and their respective recipients. INTERVENTION(S): Oocyte donors underwent a standard controlled ovarian hyperstimulation protocol and transvaginal ultrasound-guided oocyte retrieval. Oocyte recipients underwent at least one programmed hormone replacement cycle with transcervical ET. MAIN OUTCOME MEASURE(S): Thaw survival, implantation, clinical and ongoing pregnancy rates. RESULT(S): Thirty-six oocyte retrievals resulted in one ET to date. The mean numbers of oocytes that were retrieved and normally fertilized were 18.2 and 11.6, respectively. Fifty-one embryo thaw-transfer cycles were performed, with an embryo thaw survival rate of 93.5%. The clinical and ongoing pregnancy rates per ET were 52.9% and 51%, respectively. The overall implantation rate was 28.7%. The percentage of oocyte retrievals that resulted in at least one ongoing pregnancy to date was 69.4%. CONCLUSION(S): Anonymous oocyte donation can be conducted efficiently with the exclusive use of embryos cryopreserved at the pronuclear stage. This approach facilitates synchronization of the donor-recipient pair, eliminates the risk that recipients will begin hormonal therapy without embryo availability, and produces an acceptable ongoing pregnancy rate per oocyte donation.     

The graduated embryo score predicts the outcome of assisted reproductive technologies better than a single day 3 evaluation and achieves results associated with blastocyst transfer from day 3 embryo transfer

OBJECTIVE: To evaluate the graduated embryo score (GES) for predicting assisted reproductive technology (ART) outcome compared to a single morphologic evaluation on day 3 of culture (grade A: > or =7 cells; <20% fragmentation). DESIGN: Prospective cohort analysis. SETTING: Private practice. PATIENT(S): Women aged <40 years with a normal uterine cavity treated with ART (n = 106). INTERVENTION(S): Embryos were graded by GES and by day 3 morphologic characteristics alone before ET. Cycle outcomes were compared with embryo grade. MAIN OUTCOME MEASURE(S): Ongoing gestation and implantation rates. RESULT(S): Overall ongoing gestation and implantation rates were 48% and 26%, respectively. With 1+ embryo GES > or =70 (n = 77), the rates were 62% and 36%, respectively, which were significantly higher than for those with 0 embryos GES > or =70 (n = 29). With 1+ grade A embryo (n = 102), the rates were 50% and 27%, respectively. Transfer of more than one embryo GES > or =70 did not improve the pregnancy rate, but did increase the risk of multiple gestations. A single day 3 evaluation had an extremely low specificity (7%) compared to GES (47%). Graduated embryo scoring (GES) was an excellent predictor of pregnancy and implantation rates from blastocyst transfer. Day of transfer did not affect pregnancy rates, although implantation was higher from day 5 embryo transfer (ET) than from day 3 ET, as fewer embryos were transferred. CONCLUSION(S): Transfer of one or more embryo GES > or =70 predicts pregnancy and implantation rates better than a single morphologic evaluation on day 3 and achieves ART outcomes associated with blastocyst transfer from day 3 ET, making extended culture unnecessary for most patients.     

Comparison of GnRH antagonists and flareup GnRH agonists in donor oocyte cycles

OBJECTIVE: To compare the flareup GnRH-antagonist (GnRH-ant) and GnRH-agonist (GnRH-a) protocols in oocyte donation cycles, using the donor as her own control. STUDY DESIGN: A retrospective review at a university-based practice of 22 oocyte donors who underwent 29 cycles using recombinant follicle-stimulating hormone (FSH) and GnRH-ant and 28 cycles using flareup GnRH-a with recombinant FSH. Recipients (n=57) were synchronized with estrogen and progesterone supplementation. RESULTS: The total number of recombinant FSH used and days of stimulation were similar between the groups; however, cycle days 5 estradiol (341 +/- 40 vs. 473 +/- 62 pg/mL), peak serum estradiol (1721 +/- 170 vs. 3625 +/- 295 pg/mL) and the number of retrieved MII oocytes (17 +/- 1.5 vs. 29 +/- 7) were significantly higher in the flareup GnRH-a group. Similar fertilization rates, embryos transferred, clinical pregnancy rate/embryo transfer (44%, 11/25; vs. 55%, 15/27), delivered pregnancy rate/embryo transfer (32%, 8/25; vs. 52%, 14/27) and implantation rates (31 +/- 6% vs. 28 +/- 5%) were seen in each group. CONCLUSION: Both the flareup GnRH-a and GnRH-ant are shortened, simplified and efficacious protocols in oocyte donation cycles.     

The choice of embryo transfer catheter affects embryo implantation after IVF

OBJECTIVE: Comparison of two transfer catheters in an IVF program. DESIGN: Prospective, randomized clinical study. SETTING: A private tertiary care center for ART. PATIENT(S): 66 patients < 38 years of age undergoing IVF and/or ICSI. INTERVENTION(S): Patients were randomly assigned to undergo ET using the Tomcat catheter (n = 32) or the TDT catheter (n = 34). MAIN OUTCOME MEASURE(S): Primary outcome measures were implantation and pregnancy rates. Secondary outcome measures were contamination with blood and/or mucus on the tip of the catheter, cramping or patient discomfort, and time required to complete ET. RESULT(S): Use of the Tomcat catheter resulted in significantly higher implantation (25.2% vs. 8.4%) and clinical pregnancy rates (47% vs. 14.7%) compared with the TDT catheter. All secondary outcome measures were similar for both catheters. CONCLUSION(S): The choice of ET catheter may affect the success of IVF-ET cycles. Use of the Tomcat catheter compared with the TDT catheter seems to result in significantly better efficiency of the ET procedure and is more cost effective.     

Pregnancy in women with premature ovarian failure using tubal and intrauterine transfer of cryopreserved zygotes

Twenty-nine women, mean age 36.3 (SD 5.5) years, with premature ovarian failure received donated ova on an ovum donation programme. Three had Turner's syndrome, four a surgical menopause, one a chemotherapy-induced menopause and 21 had idiopathic premature ovarian failure. All donated oocytes were fertilized with frozen-thawed spermatozoa from the recipient's partner, and the resulting zygotes were frozen until transfer had been arranged. Overall, 19 women had intrauterine embryo transfer (ET) and a mean of 2.7 (SD 0.9) embryos were transferred on 20 occasions; 10 women underwent zygote intrafallopian transfer (ZIFT) and a mean of 3.5 (SD 0.5) zygotes were transferred on 10 occasions. Both groups were matched for age. The pregnancy rate per transfer was 20% in the ET group and 40% in the ZIFT group. After excluding the 10 women in the ET group who had fewer than three embryos transferred, the pregnancy rates were similar in the two groups, 30% in the ET group and 40% in the ZIFT group. Cryopreserved embryos may be used for ovum donation to preserve anonymity and still show a high pregnancy rate of at least 30% per transfer.     

Effect of duration of estradiol replacement on the outcome of oocyte donation.

PURPOSE: To investigate if duration of estrogenic endometrial stimulation can affect recipient pregnancy rate in an ovum donation program. METHODS: Each recipient received micronized 17 beta-estradiol orally in a steadily increasing dosage from 2 to 6 mg daily over a period of time varying from 5 to 76 days until oocyte were available for donation. Recipients (520 patients for a total of 835 transfer cycles) were retrospectively divided into five groups depending on the duration of E2 administration. RESULTS: No significant difference was seen in pregnancy and implantation rates between groups. There was a higher number of miscarriages in Group A (41%), p < 0.05 vs. Group B (15%), and vs. Group E (1%). Age, number of pregnancies and miscarriages, or implantation rate in donors (327 women aged < 35 years) were similar in all the five groups. CONCLUSIONS: Endometrial receptivity is tolerant to a wide duration of E2 treatment (until 2 months), while waiting for oocytes available for donation, but best results are achieved with a treatment range of 11 to about 40 days.     

A flexible protocol for artificial preparation of the endometrium without prior gonadotropin-releasing hormone agonist suppression in women with functioning ovaries undergoing frozen-thawed embryo transfer cycles

OBJECTIVE: To present our experience with a flexible and convenient protocol for artificial endometrial preparation without prior GnRH agonist suppression in patients with functioning ovaries undergoing frozen ET. DESIGN: Case series. SETTING: An IVF unit in a university hospital. PATIENT(S): All patients who underwent IVF with embryo cryopreservation from December 1997 to June 1998 and requested transfer of their frozen-thawed embryos. INTERVENTION(S): Controlled endometrial preparation for ET entailed the use of a fixed dose of 6 mg/d of micronized E2 started on day 1 of the cycle, followed by concomitant administration of micronized P placed in the vagina. MAIN OUTCOME MEASURE(S): Hormonal and endometrial profiles throughout the cycle, pregnancy rate per ET, implantation rate, and pregnancy outcome. RESULT(S): Of 185 treatment cycles in 140 patients, 8 cycles (4.3%) were canceled. In another 2 cycles, no embryos were suitable for transfer. For the remaining 175 ET cycles, the calculated pregnancy rate and implantation rate were 21.7% and 9%, respectively. The proliferative phase could be extended up to 20 days but was a mean (+/-SD) of 15+/-1.9 days. CONCLUSION(S): For patients with functioning ovaries, controlled endometrial preparation for the transfer of frozen-thawed embryos can be done successfully by using oral E2 from day 1 of the cycle followed by P preparation. Prior suppression with GnRH agonist is not necessary.