Embryo implantation rates in oocyte donation: a prospective comparison of tubal versus uterine transfers.

OBJECTIVE: To compare pregnancy and implantation rates in tubal and uterine transfers during a hormonal replacement cycle in an oocyte donation program. DESIGN: Prospective randomized. PATIENTS: Forty-two consecutive patients who entered an oocyte donation program. INTERVENTIONS: Twenty-two patients were assigned for uterine transfer and 20 for tubal embryo transfer (ET). RESULTS: Twenty-three pregnancies were achieved, 12 (54.5%) after uterine transfers and 11 (57.9%) after tubal transfers. Implantation rates in both groups are not significantly different (17.4% uterine transfers versus 21.5% tubal ETs). CONCLUSIONS: Our results suggest that in hormonal replacement cycles (uniform endometrial stimulation) there is no advantage in transferring embryos to the fallopian tube. Furthermore, embryo quality and endometrial receptivity appear to be significantly more important than the time of entrance of an embryo to the uterine cavity in determining its chances of implantation.     

Elective single-embryo transfer in oocyte donation programmes: should it be the rule?

The aim of this study is to compare the cumulative clinical pregnancy and live birth rates (fresh embryo transfers followed by frozen–thawed embryo transfers from the same stimulated cycle) between single-embryo transfer (SET) and double-embryo transfer (DET) in an oocyte donation programme. A retrospective analysis of the outcome in 1139 recipient fresh cycles (1073 from DET and 66 from SET) with at least three available embryos for transfer was performed. The clinical pregnancy rates were similar after SET (45.5%, 30/66) and DET (57.1%, 613/1073), whereas the multiple pregnancy rate was 0% and 39.5% for SET and DET, respectively. After evaluating the results using the Kaplan–Meier survival analysis in a period of 1 year, no statistically significant differences were observed in the cumulative clinical pregnancy and live birth rates (SET 82.8% and 76.4% versus DET 77.2% and 63.7%). The results indicate that for women who have at least three available embryos in oocyte donation programmes, one single embryo should be transferred as no significant decrease in the success rate is observed and multiple pregnancy can be avoided.Clinical pregnancy rate is higher when transferring two embryos compared with one. However, this also results in a higher incidence of twin pregnancy, which is associated with increased obstetric and perinatal risks. The aim of this study was to compare the cumulative clinical pregnancy and live birth rates (fresh embryo transfers followed by frozen–thawed embryo transfers from the same stimulated cycle) between single-embryo transfer (SET) and double-embryo transfer (DET) cycles in our oocyte donation programme. A retrospective analysis of the outcome in 1139 recipient fresh cycles (1076 from DET and 66 from SET) with at least three available embryos for transfer was performed. The clinical pregnancy rates were similar after SET (45.5%, 30/66) and DET (57.1%, 613/1073), whereas the multiple pregnancy rate was 0% and 39.5% for SET and DET, respectively. The cumulative clinical pregnancy and live birth rates were similar between the two strategies (SET 82.8% versus DET 77.2%) and the same was found for the cumulative live birth rates (SET 76.4% versus DET 63.7%). Our results indicate that for women who have at least three available embryos in OD programmes, one single embryo should be transferred as no significant decrease in the success rate is observed while multiple pregnancy is avoided.     

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.     

Increased endometrial thickness is associated with improved treatment outcome for selected patients undergoing in vitro fertilization-embryo transfer

OBJECTIVE: To examine possible relationships between endometrial thickness and treatment outcome after IVF and embryo transfer, and to explore the role of potential confounding factors that may influence such relationships. DESIGN: Retrospective study. SETTING: A university-affiliated clinical IVF center. PATIENT(S): Patients undergoing IVF-embryo transfer with their own oocytes. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Endometrial thickness was determined on the day of hCG administration, 2 days before oocyte retrieval. Clinical pregnancy was confirmed by ultrasound observation of fetal heart activity. RESULT(S): The study analyzed 897 IVF-embryo transfer cycles. Treatment outcome (clinical pregnancy) after IVF-embryo transfer was positively associated with increased endometrial thickness and peak E(2) concentrations in serum, and negatively associated with advanced age. Endometrial thickness was dependent on peak E(2) concentrations in serum, but was independent of patient age or duration of ovarian stimulation. Thin endometrium reduced PRs in relatively young patients (<38 years old), in patients who required more than 10 days of gonadotropin stimulation, or in patients whose embryo transfers consisted of poor quality embryos. CONCLUSION(S): Increased endometrial thickness was associated with improved treatment outcome, but this association was dependent on patient age, duration of ovarian stimulation, and embryo quality.     

Five years of single embryo transfer with anonymous and non-anonymous oocyte donation

Single embryo transfer (SET) has been the main embryo transfer strategy in the oocyte donation programme at the authors' clinic since 2000. The primary aim of this study was to evaluate the effect of SET on the clinical outcome in an unselected group of oocyte recipients. A retrospective analysis of the outcome in 142 recipient cycles (116 from anonymous donors; 26 from known donors) was performed. The oocytes from each anonymous donor were shared between two recipients if at least 10 oocytes were obtained. The proportion of SET of all fresh transfers was 77.3%. The clinical pregnancy rate (CPR) was 43.2% and the delivery rate 31.1% per embryo transfer. The outcome was similar in recipients undergoing anonymous and non-anonymous donation. The delivery rates were similar after SET (30.4%) or double embryo transfer (DET) (33.3%), whereas the twin rate was 0% after SET and 40% after DET. The implantation rate was significantly better (P < 0.01) with good-quality embryos (54.7%) compared with non-optimal embryos (27.1%). Of 152 frozen-thawed embryo transfer cycles, 78.9% were SET. The CPR was 28.3% and the twin rate was 7.1%. In fresh oocyte donation cycles, elective SET can be recommended if the embryo quality is considered good, and always if there is a contraindication for twin pregnancy.     

Trizygotic quintuplet pregnancy following simultaneous embryo splitting in an oocyte donatin cycle

Purpose To report a trizygotic quintuplet pregnancy following simultaneous embryo splitting in an oocyte donation cycle after transfer of 3 embryos. Methods A 40-year-old Caucasian female G3P1 with two previous spontaneous abortions and diminished ovarian reserve presented for IVF. The patient underwent an oocyte donation cycle secondary to diminished ovarian reserve. Three embryos were transferred per patient request. Results The three embryo transfer resulted in a trizygotic quintuplet pregnancy. Selective embryo reduction was performed at 11 weeks leaving a dizygotic twin gestation. The patient underwent SVD, or spontaneous vaginal delivery at 36 weeks gestation with respective weights and apgars of 2673 g (apgars 7(1), 9(5)) and 2722 g (apgars 7(1), 9(5)). The twins are presently doing well without complications. Conclusions Although rare, the possibility of simultaneous embryo splitting must be factored into determining number of embryos for fresh transfer.     

Blastocyst culture and transfer increases the efficiency of oocyte donation

OBJECTIVE: To determine the impact of blastocyst transfer on an oocyte donation program. DESIGN: Retrospective review of embryo transfer in an IVF clinic. SETTING: Private assisted reproductive technology unit. PATIENT(S): Two hundred and twenty nine patients undergoing oocyte donation. INTERVENTION(S): Culture of pronucleate embryos to either day 3 or day 5 followed by embryo transfer. MAIN OUTCOME MEASURE(S): Implantation rates, pregnancy rates, and multiple gestations were analyzed. RESULT(S): Implantation rates and pregnancy rates were significantly increased by moving to extended embryo culture and transfer on day 5. After day 3 transfers, implantation and pregnancy rates were 47.1% and 75%, respectively. In contrast, on day 5 these rates were increased to 65.8% and 87.6%. Concomitantly, there were significantly fewer embryos transferred on day 5 (2.1) compared to day 3 (3.2). CONCLUSION(S): Blastocyst transfer is a highly effective treatment for patients who receive donor oocytes, allowing excellent pregnancy rates while significantly reducing the incidence of high-order multiple gestations.     

Serum estradiol levels after 4 days of ovarian hyperstimulation in oocyte donors are predictive of embryo quality and clinical outcomes

OBJECTIVE: To determine whether estradiol (E(2)) levels after 4 days of ovarian hyperstimulation in leuprolide-downregulated cycles are predictive of embryo quality and pregnancy outcome in oocyte donation. MATERIAL AND METHODS: Retrospective analysis of 287 consecutive oocyte donation cycles performed at a university assisted reproduction therapy program between January 1996 and December 2000. Oocyte donors and recipients followed a non-varied standard synchronization regimen. A serum E(2) (day-5 E(2)) was obtained from egg donors the morning after leuprolide acetate downregulation and 4 days after hMG/FSH administration. Day-5 E(2) was categorized into 3 groups: group I <75 pg/ml; group II 75-350 pg/ml, and group III > or =350 pg/ml. All embryo transfers were performed 3 days after oocyte recovery. RESULTS: Elevated day-5 E(2) levels were directly correlated with higher average embryo scores, greater number of oocytes retrieved, and greater number of embryos available for transfer and cryopreservation. Improved pregnancy outcomes were also noted for group III (day-5 E(2) level >350 pg/ml). CONCLUSION: After 4 days of gonadotropin stimulation, an E(2) level of >350 pg/ml is most predictive of higher embryo grade and pregnancy outcome in oocyte donation.     

Different implantation rates after transfers of cryopreserved embryos originating from donated oocytes or from regular in vitro fertilization

Most oocyte donation programs have experienced higher pregnancy rates than usually seen in regular in vitro fertilization (IVF), suggesting that the quality of either the oocytes or the endometrium is superior. To clarify this issue we analyzed the results of transfers of 136 cryopreserved embryos originating either from donated oocytes (18 transfers) or from regular IVF (118 transfers). Transfers of embryos originating from donated oocytes took place after administrating oral estradiol (E2) valerate and vaginal micronized progesterone (P) following a regimen designed to mimic the serum levels of E2 and P observed during the menstrual cycle. Transfers of embryos originating from regular IVF took place either in the natural cycle (53 transfers) or after suppressing ovarian function with a single injection of a gonadotropin-releasing hormone agonist (GnRH-a), Decapeptyl-Retard 3.75 mg, and administering the same hormone replacement regimen (E2/P) used in oocyte donation (65 transfers). Eighteen transfers involving 24 embryos originating from donated oocytes were affected, resulting in six pregnancies (4 ongoing). The ongoing pregnancy rate per transfer was 22%. Seventy-nine embryos originating from regular IVF were transferred (53 transfers) in the natural cycle resulting in six pregnancies (2 ongoing). One hundred three other embryos originating from regular IVF were transferred (65 transfers) after administration of GnRH-a and E2/P resulting in four pregnancies. The pregnancy rate after transfers of embryos originating from regular IVF was 9% per transfer. This was significantly less than the pregnancy rate of 33% per transfer seen after the transfers of embryos originating from donated oocytes.(ABSTRACT TRUNCATED AT 250 WORDS)     

Pregnancy rate in an oocyte donation program

Oocyte donation programs offer an alternative treatment for infertile women with ovarian failure or abnormal ovarian function. Seventeen cycles of in vitro fertilization and embryo transfer with donated oocytes were performed in 13 women, with a mean age of 34.8 years. The hormonal replacement therapy consisted of a fixed dose of oral estradiol valerate, 6 mg daily, and intramuscular progesterone in oil, 100 mg daily. Estrogen and progesterone were continued for 10 more weeks after embryo transfer if pregnancy was established. After 13 embryo transfers, 8 pregnancies were obtained, for a pregnancy rate per transfer of 61.5%. Today seven pregnancies are progressing normally, including one set of twins. This results suggest that an oocyte donation program using a fixed and simple hormonal replacement therapy is an adequate treatment for these infertile couples.     

A double embryo transfer on days 2 and 4 or 5 improves pregnancy outcome in patients with good embryos but repeated failures in IVF or ICSI

The purpose of this paper was to evaluate the outcome of a double embryo transfer during the same cycle for patients who had had three or more implantation failures in IVF-ET or ICSI-ET programs after the transfer of good quality embryos in all attempts. Forty-five women who had had previous unsuccessful attempts in IVF-ET or ICSI-ET programs after transfer of good quality embryos (Group A) were included in the study. Group A was divided into two subgroups, Group A1 consisted of 34 patients who underwent embryo transfer on day 2 and day 4 after pick-up and Group A2 consisted of ten patients who underwent embryo transfer on day 2 and day 5 after pick-up. Forty-two other women with a similar unsuccessful history in IVF-ET (Group B) were studied as controls. The patients in this group had a day 4 or 5 only transfer without having an additional day 2 transfer. The outcome of the procedure was compared in the two groups. Double embryo transfer had beneficial effects on patients with good embryos but with previous failure attempts. These patients had a 38.2% clinical pregnancy rate and a 50% total pregnancy rate if the additional embryo transfer was done on day 4 and a 60% clinical and 60% total pregnancy rate if the additional embryo transfer was done on day 5. Our data showed that excellent pregnancy rates can be obtained with a commercially available medium and double embryo transfers on days 2 and 4 or 5 after pick-up for patients with good quality embryos that have had previous failure attempts in an IVF-ET program. Due to the fact that endometrial maturation varies considerably in each patient, an adequate endometrial maturation and improved uterine receptivity seem to be the reason for improved pregnancy rates with double embryo transfers. It was also shown that morullae have high viability and high potential for implantation and pregnancy.     

Follicle recruitment determines IVF productivity rate via the number of embryos frozen and subsequent transfers

IVF productivity rate is an index defined as the sum of all live births from either fresh or frozen embryo transfers arising from a single oocyte collection. This retrospective analysis over 9 continuous years used this index to understand the potential impact on pregnancy rates of milder stimulation regimens with associated reduced egg numbers. The productivity rate per collection increased in a linear and significant rate as more oocytes were recovered, more embryos frozen and more frozen embryo transfers contributed to pregnancy. This observation was true for women aged <35 years and less so for women aged 35–39 years but not for women aged 40 years and older. The contribution of frozen embryo transfer to the productivity rate rose in a linear manner, reaching over 40% of all live births with nine oocytes. The number of live births per oocyte, pronuclear embryos and thawed embryos decreased significantly but the number of live births per embryo transferred (fresh or frozen) rose with rising oocyte numbers, reflecting increasing opportunity for embryo selection. This study suggests that optimal benefits with minimal risks are gained from a model that includes both fresh and frozen transfers under stimulation generating between 8 and 12 eggs.Most of the costs and risks associated with an IVF cycle occur during the stimulation, egg collection and subsequent transfer of fresh embryos and ignore or treat separately the outcome from any subsequent frozen embryo transfers. We have used the term ‘productivity rate’ (or cumulative pregnancy rate per collection cycle) that includes outcomes from both fresh and frozen transfers as a tool to explore the impact of oocyte numbers on the ultimate chance of pregnancy. While the pregnancy rate for individual fresh and frozen transfers were largely unrelated to oocyte numbers, the cumulative chance of pregnancy rose significantly with the number of oocytes recovered. This was due to the increasing contribution of frozen embryo transfers to the overall chance of pregnancy producing more than half of all pregnancies above five oocytes. While the fertilization rate and embryo quality was independent of egg numbers, increasingly more embryos needed to be used to generate sufficient good-quality embryos for transfers as the egg numbers rose. The study found that 8–12 oocytes provided the highest cumulative chance of pregnancy with the least risk of either failed fertilization or ovarian hyperstimulation syndrome and this range could be used as a target number for individualized stimulation regimens.     

Evidence-based clinical outcome of oocyte slow cooling

In the last few years, there has been a significant improvement in oocyte cryopreservation techniques. To investigate the clinical significance of oocyte freezing, an assessment of the cumulative pregnancy rate per started cycle derived from the use of fresh and frozen-thawed oocytes was performed. Between 2004 and 2006, 749 cycles were carried out, in which no more than three fresh oocytes were inseminated either by standard IVF or microinjection. Supernumerary mature oocytes were cryopreserved by slow cooling. Cryopreservation of fresh embryos was performed in rare cases to prevent the risk of ovarian hyperstimulation syndrome using a standard embryo freezing protocol. Fresh embryo transfer cycles totalled 680, 257 of which resulted in pregnancy. The pregnancy rates per patient and per transfer were 34.3% and 37.8% respectively. When frozen-thawed oocytes were used, following 660 thawing cycles, 590 embryo transfers were performed in 510 patients. Eighty-eight pregnancies were achieved with embryos from frozen oocytes, with a success rate of 17.2% per cycle. When fresh and frozen-thawed cycles were combined, the number of pregnancies was 355, giving a cumulative pregnancy rate of 47.4%. Oocyte cryopreservation can contribute considerably to the overall clinical success, ensuring a cumulative rate approaching that achievable with embryo storage.     

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 window of embryo transfer and the efficiency of human conception in vitro

Women with ovarian failure transferred with donated oocytes provide a unique in vivo model for the elucidation of the window of implantation and efficiency of reproduction in the human. Throughout 52 ovum donation cycles, the temporal window of endometrial receptivity was tested by replacing 2- to 12-cell embryos between days 16 and 24 of hormonally and histologically defined cycles. Of 37 transfers within days 17 to 19, 15 (40.5%) conceptions occurred. Twelve (32.4%) have reached viability. Of 11 patients transferred on days greater than or equal to 20, none conceived. Likewise, no pregnancies were achieved with 4 transfers on cycle day 16. Analysis of multiple embryo transfers within the suggested window of endometrial receptivity (days 17 to 19) revealed 14 of 24 (58.3%) to be conception cycles. considering only transfers with two or more embryos, at least one of which is of high quality (grades 1 to 2), yielded a 63.2% pregnancy rate. The results indicate a very high efficiency for in vitro fecundity provided optimal conditions are attained. The concepts leading to success in the ovum donation model should set the course for continued research toward improving results in other forms of assisted reproduction.     

Establishment of a nonanonymous donor oocyte program: preliminary experience at the University of Southern California

Transvaginal ultrasound-directed oocyte retrieval was performed on eight women functioning exclusively as gamete donors for 10 patients with ovarian failure. Donors included sisters, personal friends, and compensated participants selected by the recipient couple. Oocyte donors underwent controlled ovarian hyperstimulation and transvaginal oocyte aspiration. Thirteen initiated cycles resulted in 11 embryo transfers and six ongoing pregnancies. There were no complications, and all donors stated a willingness to undergo the procedure again. The use of nonanonymous oocyte donation appears both efficacious and efficient and is recommended as an option for achieving pregnancy in women with ovarian failure.     

Embryo transfer technique as a cause of ectopic pregnancies in in vitro fertilization

Against an overall risk of around 2% ectopic pregnancies in in vitro fertilization programs around the world, we report an incidence more than three times greater (5 tubal ectopic pregnancies in 80 clinical in vitro fertilization pregnancies). Of two techniques used for embryo transfers, one produced a significantly higher risk for ectopic pregnancy (P less than 0.05). Four of the ectopic pregnancies occurred in a small group of 24 patients in whom the embryo transfer technique attempted to deliver the embryos at the uterine fundus (mean distance of catheter insertion 62.9 +/- 7.9 mm from the external cervical os). Only one ectopic pregnancy occurred in 56 patients whose embryos were transferred to a standard, generally midcavity position. It is concluded that the delivery catheter need be inserted only 55 mm as a routine and less in patients with a shortened cervix or with the hypoplastic uterus usually encountered in women with primary ovarian failure who have ovum or embryo donation. In such cases an ultrasonic measurement of length may indicate that a shorter transfer distance is required.     

Impact of retained embryos on the outcome of assisted reproductive technologies

OBJECTIVE: To assess the impact of embryo retention in the embryo transfer catheter followed by "immediate" retransfer on pregnancy outcome in women undergoing assisted reproduction. DESIGN: Retrospective analysis of embryo transfer following in vitro fertilization. SETTING: Assisted reproductive technology practice in a university in vitro fertilization program. PATIENT(S): In vitro fertilization charts for 1,812 embryo transfer cycles representing 1,139 patients between January 1997 and March 2002 were reviewed. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Pregnancy rate, implantation rate, delivery rate. RESULT(S): Three embryo transfer cycles were excluded from analysis because of missing data, leaving 1,364 embryo transfers during oocyte recovery cycles and 445 embryo transfer cycles using thawed embryos. Seventy-one embryo transfers (3.9% of all transfers) were complicated by finding retained embryos after the initial embryo transfer-all retained embryos were immediately retransferred. There was no difference in the frequency of retained embryos during oocyte retrieval versus thawed embryo cycles. The pregnancy, implantation, and delivery rates per embryo transfer were not negatively affected by embryo(s) retained in the transfer catheter. Age, fresh versus frozen embryo, use of ultrasound during the procedure, or transferring physician did not influence pregnancy outcome. CONCLUSION(S): Immediate retransfer of embryos retained in the catheter following the initial transfer attempt did not have an adverse effect on pregnancy outcome.     

Use of progestins to inhibit spontaneous ovulation during ovarian stimulation: the beginning of a new era?

Advances in oocyte and embryo cryopreservation for assisted reproduction prompted new approaches to ovarian stimulation. Attention has been paid to progesterone and its derivatives to block the LH surge, as oocyte vitrification removes possible harmful effects of progestins on endometrial receptivity. This review summarizes the current status of progestin use to inhibit ovulation during ovarian stimulation compared with conventional ovarian stimulation. Progestin-primed ovarian stimulation is shown to effectively inhibit spontaneous ovulation, without affecting the number of retrieved oocytes and embryo quality. Reproductive outcomes from ovarian stimulation with progestins appear similar to those from conventional ovarian stimulation, although large trials are needed to confirm this. Use of progestins allows better control of LH concentrations, lower costs and easier (oral) administration. Therefore, progestin-primed ovarian stimulation could be the first choice for ovarian stimulation in fertility preservation, oocyte donation and preimplantation genetic testing cycles. So-called ‘non-conventional’ ovarian stimulation protocols (luteal and random-start, double ovarian stimulation), which always require oocyte or embryo cryopreservation, may also use progestins to inhibit the endogenous LH surge. Since the ‘freeze-all’ strategy with delayed transfer is mandatory, high responders undergoing IVF could benefit more from this approach. Economic advantage remains to be demonstrated, as do pregnancy and neonatal outcomes.     

Success of in vitro fertilization and embryo transfer in relation to the causes of infertility

In 1984 163 patients were treated in our in vitro fertilization program, including 4 patients accepting embryos from the oocyte and embryo donation program. Twenty pregnancies were achieved with an average chance per transfer of 16,6%. The final success of IVF strongly depends on the cause of infertility. The best results were obtained for patients with tubal infertility, with a pregnancy rate of 15% per laparoscopy and 19% per transfer. There is a significant decrease in oocyte cleavage rate from tubal (61%) to male infertility (13%). Once the barrier of embryo formation is taken, there is no marked difference in the mean number of embryos transferred on the pregnancy rate after transfer, among the different patient groups. In patients with tubal infertility the pregnancy rate per cycle remains constant, resulting in a cumulative pregnancy rate of 40% after 3 cycles.