Cumulative pregnancy rates of two strategies: Day 3 fresh embryo transfer followed by Day 3 or Day 5/6 vitrification and embryo transfer: a randomized controlled trial

STUDY QUESTION

Are cumulative pregnancy rates better if supernumerary embryos are vitrified on Day 5/6 instead of Day 3?

SUMMARY ANSWER

The results do not show a significant difference in cumulative pregnancy rates between the Day 3 and Day 5/6 vitrification groups.

WHAT IS KNOWN ALREADY

Pregnancy and live birth rates following IVF or ICSI treatment are higher after extended embryo culture and blastocyst transfer (Day 5/6) compared to cleavage-stage (Day 3) transfer. Cumulative pregnancy rates from one oocyte retrieval (OR) cycle show no significant difference after fresh and frozen embryo transfers, but only one study has used vitrification for the cryopreservation of supernumerary embryos while four studies have used a slow freezing protocol.

STUDY DESIGN, SIZE, DURATION

Our prospective randomized controlled trial was performed in an academic centre between January 2018 and August 2020. Patients were randomized into vitrification Day 3 (n = 80) or Day 5/6 (n = 81) groups. The primary outcome was the cumulative ongoing pregnancy rate (cOPR), considering only the first pregnancy for each couple. The power calculation revealed that 75 patients were required in each group, when assuming a 50% cOPR with four embryo transfers in the vitrification Day 3 group vs two transfers in the vitrification Day 5/6 group.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Patients <38 years undergoing their first or second OR cycles were randomized at the start of the first cycle. Up to two cycles were included in the analysis. A fresh embryo transfer was performed on Day 3. Supernumerary embryos (with ≥6 cells, <25% fragmentation, and equal blastomeres) or blastocysts (with expansion grade ≥2 with inner cell mass and trophectoderm score A/B) were vitrified on Day 3 or Day 5/6, respectively, and then transferred at a later date. A time-to-event analysis was performed with the patient's first ongoing pregnancy as the event of interest and the number of embryo transfers as the time component. The statistical comparison was performed by a Cox proportional hazards model. Cumulative costs of vitrification on Day 3 vs Day 5/6 were explored and compared using Mann-Whitney U tests.

MAIN RESULTS AND THE ROLE OF CHANCE

By December 2021, 233 transfers (96 fresh and 137 frozen) in 77 patients were performed in the vitrification Day 3 group and 201 transfers (88 fresh and 113 frozen) in 77 patients were performed in the vitrification Day 5/6 group. The time-to-event analysis did not show a difference between the two arms with regard to the patient's first ongoing pregnancy as the primary study outcome (hazard ratio [HR] 1.25, 95% CI 0.82; 1.92, P = 0.30). The cumulative ongoing pregnancy rate after eight transfers (from one or two ORs) was 57% in the vitrification Day 3 group vs 58% in the vitrification Day 5/6 group. The median number of embryo transfers until a pregnancy was achieved was five vs four, respectively, in the vitrification Day 3 group vs the Day 5/6 group. Similar results were found for the secondary study outcome, i.e. clinical pregnancy with foetal heart rate (HR 1.19, 95% CI 0.78; 1.80, P = 0.41). The cumulative clinical pregnancy rate (cCPR) after eight embryo transfers was 62% in the vitrification Day 3 group vs 59% in the vitrification Day 5/6 group. The median number of transfers until a pregnancy was achieved was four in both groups. The healthcare consumption pattern differed between the two groups and we observed higher costs for the vitrification Day 3 group compared to the vitrification Day 5/6 group, although these differences were not statistically significant.

LIMITATIONS, REASONS FOR CAUTION

Although our power calculation revealed that only 75 patients were needed in each study group (β = 0.87, α < 0.05), the numbers were low. Also, different numbers of single and double embryo transfers were performed between the two groups, which may have affected the results. The cost analysis was performed on a subset of the patients and is therefore exploratory.

WIDER IMPLICATIONS OF THE FINDINGS

Our study shows no difference in the cumulative pregnancy rate nor costs after fresh and frozen embryo transfers of at most two sequential OR cycles between the Day 3 and Day 5/6 vitrification groups; however, obstetric and perinatal outcomes should be taken into account to determine the best strategy.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded as an investigator-sponsored study of S.D. by Merck nv/sa Belgium, an affiliate of Merck KGaA, Darmstadt, Germany, and by Gedeon Richter Benelux (PA18-0162). The authors declare no conflict of interest related to this study.

TRIAL REGISTRATION NUMBER

NCT04196036.

TRIAL REGISTRATION DATE

15 January 2018.

DATE OF FIRST PATIENT’S ENROLMENT

15 January 2018.

The role of acupuncture in women with advanced reproductive age undergoing in vitro fertilization-embryo transfer: A randomized controlled trial and follicular fluid metabolomics study

BACKGROUND

The objective of this study was to determine the efficacy of acupuncture on the outcome of in vitro fertilization (IVF) in elderly infertile patients with kidney qi deficiency, and to explore its possible mechanism from the perspective of pseudo-targeted metabolomics of follicular fluid.

METHODS

Sixty cases of elderly women undergoing IVF were sampled and randomly divided into 2 equal groups: the treatment and the elderly control (HA) group. In the treatment group, routine ovulation induction combined with acupuncture treatment was used. Routine ovulation induction combined with sham acupuncture was used in the HA group. Reproductive outcomes of the 2 groups were compared. The follicular fluid of patients obtained on the day of oocyte retrieval was analyzed by the ultra-high-performance liquid chromatography-mass spectrometry analysis system.

RESULTS

Compared with the HA group, the score of kidney qi deficiency syndrome in the treatment group was significantly decreased, and the 2 PN fertilization rate, high-quality embryo rate and cumulative pregnancy rate were significantly increased (P < .05). Through the identification of target metabolites, 3 metabolic pathways were found to be closely related to the developmental potential of oocytes, namely: Retinol metabolism pathway; Glycine, serine, and threonine metabolism pathway; Glycerophospholipid metabolism pathway.

CONCLUSION

From our findings, acupuncture can improve the quality of oocytes thus bettering the outcome of IVF-assisted pregnancy in elderly patients with kidney qi deficiency.

TRIAL REGISTRATION

ChiCTR1800018329.

Does the outcome of fresh embryo transfer affect the outcome of subsequent thawed embryo transfers from sibling oocytes in patients that utilized all their embryos?

The association between fresh embryo transfer (ET) outcome and the subsequent frozen-thawed (FET) cycles that follow is not clear, mainly because of incomplete embryo cohort utilization. The aim of this study was to determine if the outcome of a fresh ET affects the frozen cumulative clinical pregnancy (CP) and live birth (LB) rates resulting from the utilization of all surplus embryos from sibling oocytes. Outcome measures were the FET cumulative CP and LB rates. Multivariate logistic regression was performed for the frozen cumulative CP rate and adjusted for age, the number of oocytes, fresh ET outcome and other confounders. A total of 1313 cycles met the inclusion criteria. The FET cumulative CP and LB rates were not affected by the outcome of the fresh ET. The FET cumulative CP rate increased with the number of oocytes collected regardless of whether a pregnancy was achieved in the fresh cycle or not. In multivariate analysis, age (OR = 0.96, 95% CI 0.94-0.98), protocol (OR = 0.13, 95% CI 0.03-0.57) and the number of oocytes (OR = 1.05, 95% CI 1.02-1.07) were associated with the frozen cumulative CP rate. It is concluded that fresh ET does not impact the outcome of the vitrified-thawed embryos from the same oocyte cohort.

Long-Term Pregnancy Outcomes of Patients with Diffuse Adenomyosis after Double-Flap Adenomyomectomy

Although many studies show that patients with diffuse adenomyosis who underwent fertility-sparing surgery can have a successful pregnancy, their pregnancy outcomes are still controversial. The objective of this study was to determine long-term pregnancy outcomes and possible influencing factors after double-flap adenomyomectomy for patients with diffuse adenomyosis. A total of 137 patients with diffuse adenomyosis who underwent double-flap adenomyomectomy between January 2011 and December 2019 were studied, and correlations between pregnancy outcomes and clinical data, including age and junctional zone measured by magnetic resonance imaging (JZmax-A), were analyzed. The results show that 56 patients (40.9%, 56/137) had 62 pregnancies, including 35 natural pregnancies and 27 assisted reproduction pregnancies, after operation. A univariate regression analysis showed that the pregnancy outcomes were related to age at surgery, visual analog scale (VAS) score of preoperative dysmenorrhea, parity experience, length of infertility, and postoperative JZmax-A. A multivariate regression analysis showed that age at surgery, VAS score of preoperative dysmenorrhea, and postoperative JZmax-A were the independent indicators correlated with pregnancy outcomes. A receiver operating characteristic curve analysis showed that postoperative JZmax-A was the most valuable indicator for predicting pregnancy outcomes. Cumulative pregnancy rates during the first 3 years were 70.1% and 20.9% in the postoperative JZmax-A ≤ 8.5 mm and the postoperative JZmax-A > 8.5 mm groups, respectively. In conclusion, double-flap adenomyomectomy could improve fertility for diffuse adenomyosis, and postoperative JZmax-A might be a promising indicator for predicting pregnancy outcomes.

Predictive Factors of Conception and the Cumulative Pregnancy Rate in Subfertile Couples Undergoing Timed Intercourse With Ultrasound

The aim of this study was to determine predictive factors for pregnancy and assess the cumulative pregnancy rate (CPR) and live birth rate (CLBR) in subfertile couples undergoing timed intercourse (TI) using ultrasound. This retrospective cohort study included 285 women (854 cycles) who started TI with ultrasound between January 2017 and October 2019. The overall clinical pregnancy rate was 28.1% (80/285) per couple and 9.4% (80/854) per cycle. Pregnant women had a higher body mass index (BMI), higher percentage of irregular menstrual cycles, a shorter duration of subfertility, lower serum follicle-stimulating hormone levels, and higher anti-Müllerian hormone levels than non-pregnant women. A longer duration of subfertility (≥24 months vs. <12 months; odds ratio: 0.193; 95% confidence interval: 0.043-0.859) and endometriosis (vs. ovulatory factors; odds ratio: 0.282; 95% confidence interval: 0.106-0.746) as causes of subfertility were unfavorable factors that independently affected clinical pregnancy. In subgroup analysis, old age ≥ 35 years [vs. < 35 years; odds ratio: 0.279; 95% confidence interval: 0.083-0.938), a longer duration of infertility ≥24 months (vs. <24 months; odds ratio: 0.182; 95% confidence interval: 0.036-0.913) and a higher BMI ≥ 25 kg/m²(vs. >25 kg/m²; odds ratio: 3.202; 95% confidence interval: 1.020-10.046) in couples with ovulatory factor and a longer duration of infertility ≥24 months (vs. <24 months; odds ratio: 0.185; 95% confidence interval: 0.042-0.819) in couples with non-ovulatory factors were significant independent predictive factors for pregnancy. No significant differences were found in the cycle characteristics between pregnant and non-pregnant women. The CPR substantially increased during the first three cycles and significantly increased until the sixth cycle. No significant increase was observed in the CPR after the sixth cycle. The CLBRs substantially increased during the first three cycles and significantly increased until the fourth cycle. No significant increase was observed in the CLBRs after the fifth cycle. When comparing CPRs and CLBRs according to subfertile causes, CRPs was significantly different and CLBRs was different with borderline significance. Our findings may indicate that women with a longer duration of subfertility or subfertility due to endometriosis have poor outcomes during TI with ultrasound. Women who failed to achieve conception by the fourth or fifth cycle of TI with ultrasound may be encouraged to consider advancing to the next treatment strategy.

Effect of moderately increased thyroid-stimulating hormone levels and presence of thyroid antibodies on pregnancy among infertile women

PURPOSE

To study the effects of mildly elevated thyroid-stimulating hormone (TSH) levels and thyroid antibodies on pregnancy rates among infertile women and their potential contribution to prolonged infertility treatment.

METHODS

This case-control study included 1479 women who underwent infertility treatment between March 2015 and August 2017. Cumulative pregnancy and miscarriage rates after assisted reproductive technology (ART) or non-ART treatments were compared between women with TSH <2.5 mIU/L and those with TSH 2.5-3.5 mIU/L and between women with and without thyroid antibody positivity.

RESULTS

The cumulative pregnancy rate of women with TSH 2.5-3.5 mIU/L was similar to that of women with TSH <2.5 mIU/L in the non-ART (hazard ratio [HR], 0.85; 95% confidence interval [CI], 0.56-1.23) and ART (HR, 1.17; 95% CI, 0.93-1.47) groups. Thyroglobulin antibody (TgAb) and thyroid peroxidase antibody (TPOAb) had no correlation with cumulative pregnancy rates. In the non-ART and ART groups, HRs for TgAb were 0.87 (95% CI, 0.55-1.32) and 1.09 (95% CI, 0.84-1.39) and HRs for TPOAb were 0.88 (95% CI, 0.52-1.39) and 1.29 (95% CI, 0.97-1.68), respectively.

CONCLUSIONS

Cumulative pregnancy rates and miscarriage rates were similar between women with TSH <2.5 mIU/L and those with TSH 2.5-3.5 mIU/L and were independent of thyroid antibody positivity.

Predictive value of the serum anti-Müllerian level for spontaneous pregnancy in women after endometriosis surgery

Objective

This study was performed to assess the predictive value of the anti-Müllerian hormone (AMH) serum level for spontaneous pregnancy in women after endometriosis surgery.

Methods

In total, 124 patients with suspected ovarian endometrioma planning to undergo laparoscopic ovarian cystectomy were divided into a high AMH group (AMH > 2 ng/mL) and low AMH group (AMH ≤ 2 ng/mL) according to their preoperative AMH levels. The postoperative AMH levels were also measured, and pregnancy outcomes were followed up.

Results

Twenty-one patients were excluded, and 52 pregnancies were registered in the remaining 103 patients diagnosed with endometriosis. The pregnancy rate was significantly greater in the high than low AMH group. Receiver operator characteristics analysis of preoperative AMH, postoperative AMH, and the AMH decline rate showed that preoperative AMH was associated with the greatest area under the curve. Kaplan–Meier curves showed that women in the high AMH group had a significantly higher cumulative pregnancy rate than those in the low AMH group.

Conclusion

The preoperative AMH level might be a useful marker to predict the occurrence of natural pregnancy and could be offered as part of the fertility strategy to women who desire pregnancy after endometriosis surgery.

Fertility performance and the predictive value of the endometriosis fertility index staging system in women with recurrent endometriosis: A retrospective study

This study presents the postoperative pregnancy rate of women with recurrent endometriosis and evaluates the predictive value of the endometriosis fertility index (EFI) for the pregnancy.A total of 107 women who wished to conceive after surgery for recurrent endometriosis from January 2007 to December 2016 were included. The EFI score was calculated postoperatively. The receiver operator characteristic (ROC) curve was plotted to determine the most promising contributor to predicting pregnancy, and Kaplan-Meier (K-M) analysis was used to estimate the cumulative pregnancy rate (CPR).A total of 61 pregnancies were registered in 58 women and the remaining 49 patients failed to become pregnant. The EFI score was strongly associated with the postoperative fertility prognosis. The CPRs during the first 2 and 3 years postoperatively were 51.86% and 66.38%, respectively, and increased to 71.98% within the first 5 years postoperatively in patients with EFI scores ≥5. However, the CPR was 26.00% during the first 2 years after surgery in individuals with EFI scores <5, and there was no increase in the CRP thereafter.Women suffering from recurrent endometriosis still experienced a probability of natural pregnancy, especially patients with EFI scores ≥5. The EFI score had good predictive power for postoperative pregnancy in these patients.

In Freeze-All Strategy, Cumulative Live Birth Rate (CLBR) Is Increasing According to the Number of Blastocysts Formed in Women <40 Undergoing Intracytoplasmic Sperm Injection (ICSI)

Background: Elective freezing of all embryos, followed by frozen-thawed ET cycles emerged to prevent risk of Ovarian Hyperstimulation Syndrome and to allow endometrium recovery after Controlled Ovarian Stimulation, leading to better IVF outcomes. Blastocyst Freeze-all policy can minimize the number of abnormal embryos and consequently failed ETs, but its efficacy in terms of cumulative rates has not been studied yet. Methods: A prospective cohort observational study was carried out in Assisting Nature, Center of Assisted Reproduction and Genetics, in Thessaloniki, Greece from January 2014 until December 2017. 244 patients- normal or high responders- underwent COS with recFSH and Freeze-all policy with blastocyst culture. The included patients were 18-39 years and achieved clinical pregnancy and/or live birth or had all their vitrified blastocysts transferred in subsequent frozen-thawed cycles. Women were divided into four groups (group A: 1-2 blastocysts frozen; group B: 3-4; group C: 5-6; group D ≥7 blastocysts frozen) or seven groups (group I: 1-2 blastocysts frozen, group II: 3, group III: 4, group IV: 5, group V: 6, group VI: 7; group VII: ≥8 blastocysts frozen), according to the numerical range or to the absolute number of vitrified blastocysts, respectively. Results: The main outcome of the study was the CLBR achieved by frozen-thawed ETs, according to the number of the vitrified blastocysts. Higher CLBR are expected, when at least 3 blastocysts are formed (group B: 65.2%) and at least 2 frozen-thawed ETs are performed, reaching highest rates (88%) by group D (≥7 vitrified blastocysts). Similarly, CLBR is significantly increasing with the absolute number of the vitrified blastocysts, ranging from 20%, when 1-2 blastocysts are vitrified (group I) to 82.4% when ≥8 blastocysts are available. Conclusions: A higher number of vitrified blastocysts is associated with higher CLBR in women <40 years old- normal/high responders- following Freeze-all policy. Adopting Freeze-all strategy after blastocyst culture can contribute to improve delivery outcome after IVF, in terms of CLBR. The number of the total cryopreserved blastocysts produced might reflect the quality of the oocyte and can successfully predict the pregnancy outcome. The blastulation rate can be a robust criterion to segment or not an IVF cycle.

Characterization of a suboptimal IVF population and clinical outcome after two IVF cycles

The number of oocytes retrieved in in vitro fertilization (IVF) cycles is an independent factor influencing pregnancy rate (PR), and optimal number of oocytes would be between 10 and 15. This has led to the hypothesis that the identification of a suboptimal group of responders beforehand (4-9 oocytes retrieved) would allow physicians to optimize their PR. A retrospective observational study counting on 735 women doing an IVF treatment in our center was performed. Multivariable logistic regression was used to analyze the relationship between anti-Mullerian hormone (AMH) and antral follicle count (AFC), within suboptimal and optimal responders. We also analyzed the outcome of those patients with an estimated high probability of having an optimal response and the second cycles of those who did not get pregnant in the first cycle to observe the main significant traits that made them change from one group of responders to the other. Main results are that suboptimal responders account for almost half of our patients. Ovarian reserve markers (AMH and AFC) are significantly different in optimal and suboptimal responders, even when adjusted by age. There is a significant difference in the cumulative PR between both groups. Interestingly, 18.9% shifted from suboptimal to optimal response, and 36.9% from optimal to suboptimal.

Embryo pooling: a promising strategy for managing insufficient number of embryos in preimplantation genetic diagnosis

This retrospective study evaluated the embryo pooling strategy for managing insufficient number of embryos in preimplantation genetic diagnosis (PGD) through serial vitrification of cleavage-stage embryos from consecutive cycles, and simultaneous blastocysts biopsy in combination with blastocysts obtained in ultimate fresh cycle. A retrospective analysis of the cumulative pregnancy rate of 68 patients underwent cleavage-stage embryos accumulation (Embryo Pooling Group) and 94 patients underwent one stimulation cycle (Control Group) over a 2-year period were conducted. The blastocyst formation rate was comparable between the consecutive cycles and the ultimate cycle in embryo pooling group (56.0 versus 62.0%, p = .078). No significant difference existed between twice-vitrified and once-vitrified warmed blastocysts with respect to implantation rate (50.8 versus 46.3%, p = .658). The implantation rate and cumulative pregnancy rate of embryo pooling group were 49.0 and 67.6%, respectively, which were statistically comparable to the corresponding values of 48.9 and 73.4% obtained in control group. Our study suggests that in patients undergoing ICSI-PGD who do not reach enough embryos in a single stimulation cycle, pooling embryos from consecutive ovarian stimulation cycles is a promising strategy, which can render a cumulative pregnancy rate comparable to those patients who only require one stimulation cycle.

Sperm cystic fibrosis transmembrane conductance regulator expression level is relevant to fecundity of healthy couples

Cystic fibrosis transmembrane conductance regulator (CFTR) is relevant to sperm quality, sperm capacitation and male fertility. However, it is still unknown whether CFTR can be a potential parameter for fecundity prediction in healthy couples. In this study, 135 healthy couples were divided into groups according to their fertility. We demonstrated that the sperm CFTR expression level of healthy males who never impregnated their partners (49 cases, 38.68 ± 2.71%) was significantly lower than that of fertile men (86 cases, 46.35 ± 2.32%). Sperm CFTR expression level accurately corresponded with fertility through the logistic regression model. Receiver operating characteristic (ROC) curve analysis showed that the cut-off value of sperm CFTR expression level for fecundity prediction was 43.75%. Furthermore, cumulative pregnancy rates (CPRs) of CFTR > 43.75% group and CFTR ≤ 43.75% group during the follow-up periods were 80.6% and 49.3% respectively. Meanwhile, the mean time to pregnancy (TTP) of CFTR ≤ 43.75% group (26.79 ± 2.35) was significantly longer than that of CFTR > 43.75% group (16.46 ± 2.42). Therefore, sperm CFTR expression level is relevant to fecundity of healthy couples and shows potential predictive capacity of fecundity.

Is it justified to transfer two embryos in oocyte donation? A pilot randomized clinical trial

Multiple pregnancies involve high obstetric and perinatal risks. The aim of this study is to evaluate, in a pilot randomized control study, if the cumulative pregnancy and live birth rates of elective single embryo transfer (eSET) are comparable to the ones obtained with elective double embryo transfer (eDET). A total of 65 patients with at least two good quality embryos was randomized, 34 (52.3%) assigned to the eSET group and 31 (47.7%) to the eDET group. The cumulative pregnancy rates (eSET: 73.5% and eDET: 77.4%. RR: 0.95 95% CI: 0.72-1.25) and live birth rates (eSET: 58.8% and eDET: 61.3%. RR: 0.96 95% CI: 0.64-1.42) were similar in the two groups. The twin pregnancy rate in the fresh transfers of eDET group was 47.7% and 0% in the eSET group. The medical team decided to interrupt the study for reasons related to risks associated with elevated twin pregnancy rate, leaving low numbers of patients within the study as a result. When considering cumulative success rates, eSET and eDET are similar in terms of efficacy. However, eDET involves an increased and unacceptable twin pregnancy rate. The only prevention strategy is single embryo transfer.

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.

Life-table analysis of artificial insemination pregnancy rates for couples with male factor and idiopathic infertility

Background:  In the summer of 2002, standard guidelines for the application of assisted reproductive technology were reported by a research group of the Ministry of Health, Labor and Welfare. The present study aimed to examine the relationship between the number of cycles of artificial insemination and the cumulative pregnancy rates according to the cause of infertility. Methods:  Patients who experienced their first cycle of artificial insemination during the period of January 1999-December 2002 were included in the study and were divided into a male factor infertility group and an idiopathic infertility group. Cumulative pregnancy rates resulting from artificial insemination with the husband's semen were calculated by the life-table approach. Results:  During the study period, 139 couples entered the assisted reproduction program and underwent 581 cycles. Significant differences were observed in cumulative pregnancy rates between the two groups. Conclusion:  It is recommended that couples with male factor infertility and who fail to conceive within six or seven cycles of intrauterine insemination, consider a modification of treatment strategy such as in vitro fertilization, because cumulative pregnancy rates of this group were reached at a plateau within six or seven cycles. In contrast, patients with idiopathic infertility, the cumulative pregnancy rates appeared to increase constantly with each subsequent cycle. It is important to consider modifications of treatment strategy in the light of the cause of infertility. (Reprod Med Biol 2004; 3: 27-31).