Cumulative newborn rates increase with the total number of transferred embryos according to an analysis of 15,792 ovum donation cycles

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1 Cumulative newborn rates increase with the total number of transferred embryos according to an analysis of 15,792 ovum donation cycles Nicolas Garrido, Ph.D., M.Sc., a Jose Bellver, M.D., a Jose Remohí, M.D., a Pilar Alama, M.D., a and Antonio Pellicer, M.D. a,b a Instituto Universitario IVI Valencia, University of Valencia; and b Hospital Universitario y Politecnico La Fe, Valencia, Spain Objective: To measure the success of in vitro fertilization (IVF) of donated ova according to cumulative newborn rates (CNBR) per number of embryos required to achieve at least one newborn (EmbR), considering in addition the relevance of age and infertility etiology. Design: Survival curves and Kaplan-Meier methods were employed to analyze CNBR with respect to the number of EmbR in a retrospective cohort of oocyte donation recipients. Setting: University-affiliated infertility center. Patient(s): Infertile couples undergoing IVF with oocyte donation. Intervention(s): None. Main Outcome Measure(s): CNBR per EmbR. Result(s): The CNBR increased radically (up to 64.8%) between 1 and 5 EmbR, moderately (85.2%) between 5 and 15, and slowly thereafter, reaching a plateau at 15 embryos (92.4%) and peaking after 25 EmbR (96.8%), thus demonstrating that the chances of success vary as failed attempts accumulate. Patient age was not a negative factor, and indication for oocyte donation was also irrelevant to the outcome. The data showed an overall mean number of 2.6 embryo transfers and 5.8 transferred embryos per newborn. Conclusion(s): The relationship between CNBR and number of EmbR provides pragmatic and exact information about the probability of success with oocyte donation, which is of obvious relevance to patient counseling. (Fertil Steril Ò 2012;98: Ó2012 by American Society for Reproductive Medicine.) Key Words: Assisted reproduction, cumulative rates, IVF, newborn, number of embryos, ovum donation Discuss: You can discuss this article with its authors and with other ASRM members at Use your smartphone to scan this QR code and connect to the discussion forum for this article now.* * Download a free QR code scanner by searching for QR scanner in your smartphone s app store or app marketplace. In many developed societies there is a trend among women to delay the age at which they wish to become mothers. As a result, reduced ovarian reserve and oocyte quality often affect women s chances of becoming pregnant (1), so the demand for donated oocytes has increased (2 8). It is assumed that oocyte donation (OD) yields higher pregnancy and implantation rates than standard in vitro fertilization/intracytoplasmic sperm injection (IVF-ICSI) cycles with the patients own oocytes, as documented by both independent centers and public registries (2 4). The reason for this is undoubtedly linked to the selection of young, Received September 20, 2011; revised March 28, 2012; accepted April 24, 2012; published online May 24, N.G. has nothing to disclose. J.B. has nothing to disclose. J.R. has nothing to disclose. P.A. has nothing to disclose. A.P. has nothing to disclose. Presented in part at the 65th Annual Meeting of the American Society for Reproductive Medicine in Denver, Colorado, October 23 27, Reprint requests: Nicolas Garrido, Ph.D., M.Sc., Instituto Universitario IVI Valencia, Plaza de la Policía Local, 3, 46015, Valencia, Spain ( nicolas.garrido@ivi.es). Fertility and Sterility Vol. 98, No. 2, August /$36.00 Copyright 2012 American Society for Reproductive Medicine, Published by Elsevier Inc. doi: /j.fertnstert healthy women as donors, which would suggest that uterine receptivity is secondary. Improvement in the results obtained with OD has been reported over the years (2, 5), but there have been few reliable studies investigating repeated treatments in cases of failure in general and the cumulative rates in particular. Moreover, the achievement of a newborn is not always evaluated as the end point in the studies published to date. We have recently reported an innovative new approach to measuring the success of assisted reproduction treatment (ART) by analyzing, in IVF cycles using the patient s own oocytes, VOL. 98 NO. 2 / AUGUST

2 ORIGINAL ARTICLE: ASSISTED REPRODUCTION increases in cumulative newborn rates according to the total number of embryos replaced in consecutive embryo transfers (ETs) until a newborn is achieved (6). This analysis allow an accurate description of the rate at which newborns are attained, thus providing doctors with reliable information about the results that can be expected in the case of couples who have experienced several failed treatments. This would enable physicians to counsel patients about repeating or abandoning treatment, depending on their specific chances of success and an evaluation of cost effectiveness. In our cohort, the rate of newborns per transferred embryo increased substantially between the first and fifth embryo, slightly lowered between the fifth and tenth, and became even less thereafter; a plateau and different limits were detected that depended on the woman s age and the cause of infertility (6). We describe the changes in cumulative newborn rates (CNBR) per total number of embryos replaced until a newborn was achieved (EmbR) in over 15,000 ETs performed as part of our OD program since 1998, where each embryo transferred is considered a chance to achieve a newborn and the results are stratified according to age and infertility etiology. MATERIALS AND METHODS Patients A retrospective cohort study was performed with the data from OD cycles performed between January 1998 and February 2010 at the Instituto Universitario IVI Valencia (Spain) that ended in ET. The inclusion criterion was a fresh or frozen-thawed ET without preimplantational genetic screening for embryo aneuploidies. Institutional review board approval was obtained for this study (#1110-C-093-NG). Given that the aim of the study was to evaluate the significance with respect to CNBR of the total number of embryos transferred that were required to achieve at least one newborn, we considered each of the consecutive OD cycles performed for each couple until treatment was discontinued (>2 years, considered statistically as a censored time) or until at least one newborn was delivered, which was the primary outcome measure. Our study differs from others published until now in that our unit of analysis was the number of embryos transferred and that the cumulative rates per unit of analysis were measured rather than raw per transfer, stimulation, or patient rates. All patients failing to achieve a newborn (i.e., negative pregnancy test result or miscarriage) in a given cycle were eligible for a subsequent cycle. All patients achieving a newborn and who returned for additional OD treatments (to achieve a second pregnancy) were also included (7.7% of the total number of cycles analyzed). These new attempts were considered as new treatments. A separate analysis of only the patients who had yet to achieve their first child (Supplemental Fig. 1, available online) rendered very similar results, sustaining an extremely high statistical power even when approximately 8% of the cases were excluded. Oocyte Donors and Recipients Oocyte donor recruitment and management were performed following protocols previously described in detail elsewhere (2, 5, 7). Screening for sexually transmitted diseases (human immunodeficiency virus, hepatitis B virus, and hepatitis C virus included) was also performed. In Vitro Fertilization and Fresh-Embryo Transfer Once oocytes were obtained and matched with a recipient according to phenotypical characteristics, insemination was performed according to one of two IVF methods, namely, by means of microdrops containing the oocyte and sperm cells (classic IVF) or by mechanically introducing sperm into the oocyte by ICSI (8). Embryo transfer (ET) took place between 2 and 6 days after oocyte retrieval. The number of embryos transferred complied with current national regulations and responded to the individual patient s needs, requests, and possibilities. This number ranged from 1 to 3 since 2006, at which time Spanish law established this limit. Frozen-Thawed ET Cryopreservation was performed 3 days after oocyte retrieval or during the blastocyst stage, and only with embryos that were considered viable according to morphologic criteria. Frozen-thawed cycles employing cryopreserved embryos were performed following a natural cycle in which ovulation was triggered with human chorionic gonadotropin (hcg) when the preovulatory follicle reached 18 to 19 mm or after an artificial cycle in which exogenous hormones were administered (9). In both types of cycles, the luteal-phase was supported with vaginal micronized progesterone. Thawed embryos were considered viable if more than 50% of the blastomeres and the zona pellucida were unaffected by the thawing process. Data Collection Data were obtained from donors and patient s clinical charts, and included age, body mass index (BMI) and basal serum follicle-stimulating hormone (FSH) levels. Other parameters recorded for each cycle were total dose of gonadotropins, serum estradiol (E 2 ) levels on the day of hcg administration, oocytes obtained per cycle, type of insemination (IVF and/or ICSI), embryos replaced, embryos cryopreserved, and outcome in terms of pregnancy, miscarriage and newborns. The primary outcome was the delivery of one or more live infants, confirmed by medical records. Indications for OD were as follows: low response to conventional controlled ovarian stimulation due to either diminished ovarian reserve or age (>38 years), ovarian failure due to premature or natural menopause, endometriosis, repeated IVF failure or recurrent miscarriage. Statistical Analysis Statistical analysis was performed using Statistical Package for Social Sciences 17 (SPSS, Inc.). The cumulative probability of a first newborn for each woman undergoing treatment during the study period was estimated using the Kaplan-Meier method, according to the total number of EmbR in each set of treatments, defining a set of treatments as the total number of consecutive OD performed until a newborn was achieved or the patient abandoned treatment. Adjustments were made 342 VOL. 98 NO. 2 / AUGUST 2012

3 Fertility and Sterility when the number of ETs was equal to the number of embryos implanted (by adding one embryo) and when the number of implanted embryos was different from the number of ETs (number of embryos most likely needed to achieve a newborn) (10), as previously validated elsewhere (6). Data for patients who did not return for treatment when no newborn was achieved were statistically considered as censored. Data were stratified according to the woman s age and infertility etiology, and log-rank Breslow and Tarone-Ware tests were employed to compare the survival curves according to each of these cases. With respect to indication for OD, only cases in which the clinical chart showed that infertility was caused by a single factor were considered. Chi square tests and analysis of variance (followed by Bonferroni s post-hoc test) were applied to detect statistical differences among the groups in terms of proportions or means. A two-sided (P<.05) was considered statistically significant. RESULTS Characteristics of the Donors and Patients All our oocyte donors were aged between 18 and 34 years old. The total dose of gonadotropins used in the ovarian stimulation cycles was 2,238 IU (95% confidence interval [CI], 2,210 2,265), which resulted in mean E 2 levels of 2,772 pg/ml (95% CI, 2,210 2,265) on the day of hcg administration. Our cohort consisted of 8,895 women who underwent a total of 15,792 OD ET cycles, resulting in a total of 35,839 embryos transferred as part of 9,657 sets of treatments. Of these, 762 patients underwent treatment for a second child, and these new attempts were considered to be independent and were also included. Baseline characteristics of the patients at the start of cycle 1 were as follows: 39.9 years old (95% CI, ) 2,143 (22.2%) under 35 years; 1,022 (10.6%) of 36 to 37 years; 1,248 (12.9%) of 38 to 39 years; 1,547 (16.0%) of 40 to 41 years; 1,487 (15.4%) of 42 to 43 years; and 2,216 (22.9%) of over 43 years and with a mean body mass index of 23.1 kg/m 2 (95% CI, ). The main indications for OD were as follows: 4,101 (46.1%) advanced age, 640 (7.2%) failure of previous ART, 534 (6.5%) endometriosis, 1,459 (16.4%) low response to conventional controlled ovarian hyperstimulation, 1,992 (22.4%) ovarian failure, and 169 (1.9%) recurrent miscarriage. Overall OD Cycle Results A total of 8,605 biochemically confirmed pregnancies (54.5% per ET [95% CI, ]) were obtained, of which 2,479 (28.8% per pregnancy [95% CI, ]) did not evolve, resulting in 6,126 newborns (38.8% per ET [95% CI, ]) and an overall mean number of 2.6 (95% CI, ) ETs and 5.8 transferred embryos per newborn (95% CI, ). There were 12,934 ETs on days 2 to 3, achieving 4,875 newborns, indicating a 37.7% (95% CI, ) newborn rate per transfer, and 2,858 ETs achieving 1,251 newborns from the blastocyst stage, for a 43.8% (95% CI, ) newborn rate per transfer. Tables 1 and 2 provide a clear picture of the patient s clinical characteristics and their results according to the number of embryos they required to achieve a newborn, TABLE 1 Clinical characteristics of the treatments according to the number of embryos transferred to reach a newborn in oocyte donation. No. of embryos transferred per newborn Overall P value 1 5 >5 10 >10 15 >15 20 >20 25 >25 Characteristic Mean age of the recipients (y) ( ) a ( ) a ( ) a ( ) ( ) ( ) <.05 No. of cycles with transfer 10,565 3, ,850 (83.8) 2,892 (77.4) 817 (86.7) 246 (90.8) 121 (90.1) 131 (89.7) Fresh embryo transfers (% of total) IVF (% of fresh) 2,121 (24.0) 819 (28.3) 295 (36.1) 126 (51.2) 68 (56.2) 60 (45.8) IVF/ICSI (% of fresh) 672 (7.6) 103 (3.6) 18 (2.2) 0 (0) 4 (3.3) 4 (3.1) ICSI (% of fresh) 6,057 (68.4) 1,970 (68.1) 504 (61.7) 120 (48.8) 49 (40.5) 67 (51.1) Thawed embryo transfers 1,715 (16.2) 843 (22.6) 125 (13.3) 25 (9.2) 12 (9.9) 15 (10.3) (% of total) Mean no. of transfers needed 1.31 ( ) a 2.94 ( ) a,b 4.00 ( ) a,b,c 5.20 ( ) a,b,c,d 6.65 ( ) a,b,c,d 8.94 ( ) a,b,c <.05 (95% CI) MII received/cycle (95% CI) 9.20 ( ) a 8.93 ( ) a,b 8.41 ( ) a,b 8.25 ( ) a,b 7.87 ( ) 8.56 ( ) <.05 Embryos transferred/cycle 2.12 ( ) a 2.59 ( ) a,b 3.21 ( ) a,b,c 3.49 ( ) a,b,c 3.43 ( ) a 3.65 ( ) a <.05 (95% CI) 1.56 ( ) a 1.20 ( ) a,b 0.60 ( ) a,b,c 0.29 ( ) a,b,c 0.47 ( ) a,b 0.47 ( ) a,b <.05 Embryos cryopreserved/cycle (95% CI) Note: The overall cohort includes all women in whom the total number of embryos transferred in consecutive cycles belongs to this category. CI ¼ confidence interval; ICSI ¼ intracytoplasmic sperm injection; IVF ¼ in vitro fertilization; MII ¼ metaphase II. Equal superscripts within the same row denote statistical differences between the first category and the remaining, from left to right. VOL. 98 NO. 2 / AUGUST

4 ORIGINAL ARTICLE: ASSISTED REPRODUCTION TABLE 2 Cycle outcomes according to number of embryos transferred to reach a newborn in oocyte donation. No. of embryos transferred per newborn Overall P value 1 5 >5 10 >10 15 >15 20 >20 25 >25 Characteristic No. of women 8,071 1, Embryo transfers (15,792) 10,565 3, Pregnancies/transfer 6,610 (62.6, ) a 1,519 (40.7, ) a,b 325 (34.5, ) a,b,c 69 (25.5, ) a,b,c 48 (36.1, ) a,b 34 (23.3, ) a,b,c <.05 (%, 95% CI) Miscarriages/pregnancy 1,394 (21.1, ) 779 (51.3, ) 199 (61.2, ) 41 (59.4, ) 39 (81.2, ) 27 (79.4, ) <.05 (%, 95% CI) Newborn/transfer (%, 95% CI) 5,216 (49.4, ) 740 (19.8, ) 126 (13.4, ) 28 (10.3, ) 9 (14.8, ) 7 (4.7, ) <.05 2, Women eligible to be included in the next category % of deliveries with a newborn in each category among the entire population of newborn (n ¼ 6,126) Singleton (%) 3,646 (70.0) 476 (64.3) 76 (60.3) 19 (67.9) 6 (66.7) 6 (85.7) Twins (%) 1,539 (29.5) 253 (34.2) 49 (38.9) 9 (32.1) 3 (33.3) 1(14.3) Triplets and quadruplets (%) 31 (0.6) 11 (1.5) 1 (0.8) Note: The overall cohort includes all women in whom the total number of embryos transferred in consecutive cycles belongs to this category. CI ¼ confidence interval. Equal superscripts within the same row denote statistical differences between the first category and the remaining, from left to right. including the number of retrieved oocytes, percentage of cycles involving ICSI, classic IVF, transfer of fresh or frozen embryos, and number of embryos transferred or frozen. The results are comparable independent of the number of embryos necessary to achieve a newborn as regards the recipient s age, type of insemination, and transfer of fresh or frozen-thawed embryos. Logically, the number of transfers required to achieve a newborn increased with the EmbR, as was the case with the number of embryos transferred per cycle. It is interesting that the mean number of embryos transferred in cases requiring a higher number of EmbR was close to three, which shows that these women tended to be among those treated before 2006, in which case there was no limit regarding the number of embryos transferred in a single cycle. Indeed, this is supported by the fact that comparable numbers of oocytes were donated but fewer embryos were frozen in the groups with a high EmbR. The description of the success rates of OD according to EmbR, pregnancies per transfer, miscarriages per pregnancy, and newborns per cycle is shown in Table 2. A clear decrease was observed in the pregnancy rates per transfer when comparisons were made with the group in which newborns were achieved with one to five embryos (approximately 63% rate of pregnancy per transfer); there was a drop to near 40% in the following category (5 10 embryos), and to 30% from there onward. Table 2 illustrates a marked increase in miscarriage rates per embryo transferred among women requiring higher numbers of EmbR to achieve their first newborn. In the case of women needing at least 20 embryos transferred to achieve a newborn, miscarriage rates per pregnancy were almost fourfold those of women achieving a child within the first five embryos transferred (80% vs. 21.1%). This high miscarriage rate, rather than an inability to become pregnant, would appear to underlie the poor success rates in women requiring a high number of embryos transferred to achieve a newborn. The data also confirm that almost 85% of the babies conceived through OD were done so within the first five EmbR, with only 2.5% of the total number of babies being born to couples undergoing more than 10 EmbR. As the number of failed attempts rose, the number of embryos transferred in a single replacement tended to increase. It is interesting that the number of frozen embryos decreased as patients required more embryos to achieve a newborn. Overall and Stratified CNBR To reach a CNBR of 64.8%, five embryos were sufficient (95% CI, ), which represents an increase of approximately 12.3% per embryo transferred in consecutive cycles. In patients in whom up to 10 embryos were replaced, the CNBR was 85.2% (95% CI, ), which represented an increase of approximately 3.9% between 5 and 10 embryo transferred. When up to 15 embryos were replaced, the CNBR was 92.4% (95% CI, ), with an increase of 1.4% in the CNBR per embryo transferred being observed in this category. Finally, in patients requiring 25 embryos transferred, the maximum CNBR was 96.8% (95% CI, ), which was 344 VOL. 98 NO. 2 / AUGUST 2012

5 Fertility and Sterility only slightly higher (approximately 0.4% per embryo transferred) than cases in which 10 and 15 embryos were needed. There was a clear drop in the likelihood of achieving a newborn per additional embryo transferred among patients with a wide history of previous failures. Figure 1A represents the CNBR according to the recipient s age, showing that all curves practically overlapped and were statistically comparable, without any noticeable trend. In both extremes patients younger than 35 years and older than 40 years the results were very similar (<5 EmbR, 10, 15, 20, and >25 EmbR). Regarding the indication for OD (Fig. 1B), the results were also comparable, showing that OD outcome was exactly the same regardless of the woman s infertility etiology, with equivalent results regarding EmbR. Moreover, the overall impression provided by the curves is that almost all the patients, regardless of age or infertility etiology, had extremely high chances of achieving a newborn after repeated OD treatments. The effects of day 2 3 versus day 5 6 ET can be seen in Supplemental Figure 2 (available online): newborns were achieved earlier with blastocysts, although the long-term results were comparable. DISCUSSION Our cohort is the largest ever analyzed almost 9,000 couples and more than 35,000 ETs to evaluate ART results obtained using donated oocytes in successive cycles. Our aim in doing this was to provide more accurate and precise information with which to advise patients after failed treatments. In this way, we wish to establish new criteria for counseling patients, as we have in the case of IVF using patients own oocytes (6). Our analysis shows that OD success can be predominantly achieved within the first five embryos transferred. Couples failing to achieve a newborn within this range have a diminished but reasonable likelihood of fulfilling their dream by increasing the number of EmbR to 10. Subsequently, chances increase only 1.4% per additional embryo; from 15 EmbR onward, each new transfer raises the CNBR by only 0.4%. At this point, a plateau is reached, and further treatments are not likely to succeed. It is important to stress that, though our findings show that the likelihood of a newborn increases as the number of ET rises in consecutive cycles, they do not support the use of indiscriminate ovarian stimulation for the retrieval of oocytes from donors or multiple-embryo transfers per cycle, which can lead to problems such as ovarian hyperstimulation syndrome or multiple pregnancies. We believe that the undesirable side effects of such practices must be considered more important than the potential clinical benefits of making more embryos available or performing further transfers. Our results are reassuring in that they show that age has little influence on endometrial receptivity, although it should be pointed out that women aged >50 years are not accepted in our program. Similarly, indication for OD did not affect overall outcome. The advantage of this novel approach to analyzing data is that it has allowed us to measure ART results as a follow-up study and to create survival curves in which the variable time is replaced by opportunities to reach a newborn (embryos). It has also enabled us to evaluate each ET as a single part of the whole treatment process, as well as the total number of embryos transferred, a key parameter of success that was not considered by previous reports (11 17). This approach also allows us to distinguish between patients receiving an equal number of transfers but different numbers of embryos per transfer, which can have a considerable effect on their chances of success. Moreover, our data are not restricted to six cycles, as in other previously published reports (17). Wehaveanalyzedcasesofmore than nine ETs, and this has allowed us to determine when a plateau in the results is reached and to establish the real upper limits of OD. As expected, the number of cycles needed to achieve a newborn tended to increase with the total number of embryos required to succeed, from approximately one ovarian stimulation when the total number of EmbR was 1 to 5 to almost 9 when more than 25 embryos were needed. It is interesting that the cases that required the highest number of replaced embryos to achieve a newborn were also those with FIGURE 1 Kaplan-Meier curves for cumulative newborn rates depending on the total number of embryos transferred required to achieve a newborn, excluding preimplantational genetic screening treatments, categorized by (A) age and (B) main cause of infertility. VOL. 98 NO. 2 / AUGUST

6 ORIGINAL ARTICLE: ASSISTED REPRODUCTION the highest miscarriage rates, in agreement with data published for success rates of IVF with the woman s own oocytes (6). Even more intriguingly, if all patients received oocytes of a similar quality, it seems that the differences in the number of embryos required to achieve a newborn were related principally with uterine receptivity or sperm characteristics. The latter factor could lie behind the differential success rates among some couples, as a decrease in the number of frozen embryos as the EmbR increases is an indicator of bad embryo quality. Further research on this topic is underway in our center. This report does have some limitations. First, we did not evaluate single-, double-, or triple-embryo transfers, but our center s policy is to keep as low as possible the number of embryos transferred per attempt. Second, embryo quality was not considered, due to the difficulties associated with its numerical quantification. We have preferred to refer to the number of embryos transferred, as this is an objective numerical parameter; after all, a minimum embryo quality is always required for ET. Our study demonstrates that IVF using OD is a highly successful procedure and that CNBR increases with consecutive attempts until a plateau is reached, while OD indication and recipient age are irrelevant to the outcome. The insight acquired through this study enables us to provide patients with accurate and individualized information concerning the probability of achieving a newborn based on the number of ETs they have already undergone, also considering the total number of embryos replaced. By determining at which point of the treatment curve a patient is located at a given time, we can help in the hardest decision of the process of ART: whether to continue with the treatment or to remain childless or adopt. Acknowledgments: The authors thank all the clinicians, embryologists, and technicians whose work helped to generate the data analyzed in this study for their cooperation and enthusiasm, and Brian Normanly for his exhaustive work in editing the manuscript. REFERENCES 1. Andersen AN, Goossens V, Gianaroli L, Felberbaum R, de Mouzon J, Nygren KG. Assisted reproductive technology in Europe, Results generated from European registers by ESHRE. Hum Reprod 2007;22: Remohi J, Gartner B, Gallardo E, Yalil S, Simon C, Pellicer A. Pregnancy and birth rates after oocyte donation. Fertil Steril 1997;67: Sauer MV, Kavic SM. Oocyte and embryo donation 2006: reviewing two decades of innovation and controversy. Reprod Biomed Online 2006;12: Society for Assisted Reproductive Technology, American Society for Reproductive Medicine. Assisted reproductive technology in the United States: 2001 results generated from the American Society for Reproductive Medicine/Society for Assisted Reproductive Technology registry. Fertil Steril 2007;87: Budak E, Garrido N, Soares SR, Melo MA, Meseguer M, Pellicer A, et al. Improvements achieved in an oocyte donation program over a 10-year period: sequential increase in implantation and pregnancy rates and decrease in high-order multiple pregnancies. Fertil Steril 2007;88: Garrido N, Bellver J, Remohi J, Simon C, Pellicer A. Cumulative newbornrates per total number of embryos needed to reach newborn in consecutive in vitro fertilization (IVF) cycles: a new approach to measuring the likelihood of IVF success. Fertil Steril 2011;96: Garrido N, Zuzuarregui JL, Meseguer M, Simon C, Remohi J, Pellicer A. Sperm and oocyte donor selection and management: experience of a 10 year follow-up of more than 2100 candidates. Hum Reprod 2002;17: Gamiz P, Rubio C, de los Santos MJ, Mercader A, Simon C, Remohi J, et al. The effect of pronuclear morphology on early development and chromosomal abnormalities in cleavage-stage embryos. Hum Reprod 2003;18: Soares SR, Troncoso C, Bosch E, Serra V, Simon C, Remohi J, et al. Age and uterine receptiveness: predicting the outcome of oocyte donation cycles. J Clin Endocrinol Metab 2005;90: Domenech JM, editor. Anonymous Fundamentos de Dise~no y Estadística. UD 1: Descripcion de datos cuantitativos. Barcelona, Spain: Signo; Elizur SE, Lerner-Geva L, Levron J, Shulman A, Bider D, Dor J. Cumulative live birth rate following in vitro fertilization: study of 5,310 cycles. Gynecol Endocrinol 2006;22: Witsenburg C, Dieben S, Van der Westerlaken L, Verburg H, Naaktgeboren N. Cumulative live birth rates in cohorts of patients treated with in vitro fertilization or intracytoplasmic sperm injection. Fertil Steril 2005;84: Olivius K, Friden B, Lundin K, Bergh C. Cumulative probability of live birth after three in vitro fertilization/intracytoplasmic sperm injection cycles. Fertil Steril 2002;77: Klipstein S, Regan M, Ryley DA, Goldman MB, Alper MM, Reindollar RH. One last chance for pregnancy: a review of 2,705 in vitro fertilization cycles initiated in women age 40 years and above. Fertil Steril 2005;84: Fukuda J, Kumagai J, Kodama H, Murata M, Kawamura K, Tanaka T. Upper limit of the number of IVF-ET treatment cycles in different age groups, predicted by cumulative take-home baby rate. Acta Obstet Gynecol Scand 2001;80: Lintsen AM, Eijkemans MJ, Hunault CC, Bouwmans CA, Hakkaart L, Habbema JD, et al. Predicting ongoing pregnancy chances after IVF and ICSI: a national prospective study. Hum Reprod 2007;22: Malizia BA, Hacker MR, Penzias AS. Cumulative newbornrates after in vitro fertilization. N Engl J Med 2009;360: VOL. 98 NO. 2 / AUGUST 2012

7 Fertility and Sterility SUPPLEMENTAL FIGURE 1 Analysis of all the cycles seeking for the first newborn. VOL. 98 NO. 2 / AUGUST e1

8 ORIGINAL ARTICLE: ASSISTED REPRODUCTION SUPPLEMENTAL FIGURE 2 Analysis of the cycles depending on the day of embryo transfer. 346.e2 VOL. 98 NO. 2 / AUGUST 2012