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1.
OBJECTIVE: To identify whether the cause, site of ductal obstruction, and characteristics of fluid aspirates are associated with the cryosurvival and fertility after thawing of sperm obtained during reconstruction of the excurrent ducts with microsurgical epididymal sperm aspiration, vasal sperm aspiration, or both. DESIGN: Prospective study. SETTING: Andrology center at a tertiary care institution. PATIENT(S): Men undergoing reconstruction of the excurrent duct and sperm aspiration (n = 42) or microsurgical epididymal sperm aspiration (n = 11). INTERVENTION(S): Sperm were tested for an association with the cause and site of obstruction. Fertilization and pregnancy rates after sperm aspiration and intracytoplasmic sperm injection (ICSI) were evaluated for fresh and frozen aspirates. MAIN OUTCOME MEASURE(S): Motile sperm count and percentage motility after thawing. RESULT(S): The motile sperm count before freezing was significantly higher in the caput epididymis than in the corpus. The motile sperm count before freezing was related inversely to the distance from the caput where the sperm were aspirated. Sperm from clear and opaque fluid aspirates had better percent motility than those from cloudy and creamy fluid aspirates. High fertilization and pregnancy rates were achieved using both fresh and frozen epididymal sperm. CONCLUSION(S): None of the factors studied was associated with cryosurvival of aspirated epididymal or vasal spermatozoa. Because motility is low after thawing, these specimens are best used with ICSI.  相似文献   

2.
A novel sperm collection method by epididymal micropuncture combined with perivascular nerve stimulation has been developed to obtain as many clean sperm as possible for IVF for patients with surgically irreparable vasal obstruction. To assess whether the new technique could improve the fertilization and pregnancy rates obtained when attempting microsurgical epididymal sperm aspiration (MESA) to retrieve epididymal sperm from such patients, a prospective randomized comparative study was conducted. Twenty-nine cycles of conventional MESA with ICSI were performed on 25 couples with congenital bilateral absence of the vas deferens (CBAVD) and four failed vasovasostomy cases (group 1). Thirty cycles of epididymal micropuncture with nerve stimulation with ICSI were performed on 28 couples with CBAVD and two failed epididymovasostomy cases (group 2). The mean volume of epididymal fluid and sperm motility in group 2 was significantly higher than that in group 1 (p < .001). Both fertilization and pregnancy rates in group 2 were significantly higher than those in group 1 (p < .001 and p < .03). This novel epididymal sperm collection method for ICSI can provide significantly higher fertilization and pregnancy rates than conventional MESA for ICSI.  相似文献   

3.
OBJECTIVE: To compare the survival rate and pregnancy rate (PR) of embryos from intracytoplasmic sperm injection (ICSI) or conventional IVF, which were cryopreserved at the pronuclear stage in cycles where fresh transfer was deferred. DESIGN: Comparative observational study. SETTING: University-associated IVF center. PATIENT(S): Ninety-nine patients who deferred ET and had all their embryos cryopreserved at the pronuclear stage after 153 oocyte retrievals. Thirty-nine patients had their oocytes inseminated by ICSI and 60 patients had conventional IVF insemination. INTERVENTION(S): All embryos were frozen-thawed at the two pronuclear stage and allowed to cleave for 2 days before transfer. MAIN OUTCOME MEASURE(S): Survival rate (morphologically intact after thaw), cleavage rate (cleaved by time of transfer), and the clinical PR after frozen ET. RESULT(S): In the ICSI group, 205 embryos were thawed for use in 57 frozen ETs; in the IVF group, there were 527 embryos thawed for use in 149 frozen ETs. There was no significant difference in any of the outcome measures by insemination method: survival rates (ICSI, 93.2%; IVF, 94.8%); cleavage rates (ICSI, 95.2%; IVF, 94.7%), and clinical PR (ICSI, 14.0%; IVF, 17.4%). CONCLUSION(S): Pronuclear embryos resulting from ICSI can be cryopreserved successfully, thawed, and the survival rate and PR are comparable to conventional IVF.  相似文献   

4.
Four distinct studies were carried out using two data sets of percutaneous epididymal sperm aspiration (PESA) and intracytoplasmic sperm injection (ICSI) procedures performed from March 1993 to January 1997. In study A, an analysis of 181 ICSI treatment cycles following PESA revealed a successful epididymal sperm retrieval rate of 83%. It confirmed that PESA is an effective sperm retrieval method and the associated ICSI pregnancy rate (35% per embryo transfer) compared favourably with that of other sperm retrieval methods. In study B, the relevance of a prior diagnostic PESA procedure was ascertained by comparing the sperm retrieval rates in two groups of patients having their first ICSI treatment cycle with spermatozoa retrieved through PESA. Group B1 (n = 50) had diagnostic PESA prior to the ICSI treatment cycle PESA procedure, unlike patients in group B2 (n = 64) who did not. The sperm retrieval rate in the treatment cycle procedure was not different at 90 and 82.8% for groups B1 and B2 respectively. However, the discontinuation of diagnostic PESA is fraught with problems including liability to medico-legal sanctions. In study C, analysis of 177 treatment cycles involving PESA and ICSI revealed a successful sperm retrieval rate by PESA of 82% in the first cycle, 93% in the second, 96% in the third and 100% in the fourth cycle. The same trend was evident when sperm retrieval was examined in relation to each of the epididymides. Retrieved spermatozoa were found to be motile in 67-100% of cases and the frequency of samples containing motile spermatozoa did not decrease with increase in the number of PESA attempts. These results show that PESA does not jeopardize future epididymal sperm retrieval. In study D, the outcome of treatment with ICSI using ejaculated spermatozoa (305 cycles) (group D1) was compared with that of ICSI using spermatozoa obtained through PESA (54 cycles) (group D2). The median age of women in the two groups of couples was similar (34 years). In group D1, 70% of metaphase II oocytes were fertilized compared with 61% in group D2 (P < 0.01). The cleavage rate and the median numbers of transferred and cryopreserved embryos were similar in both groups. There was no significant difference between the clinical pregnancy rates (33 and 42% in groups D1 and D2 respectively). Our results show that the outcome of PESA-ICSI treatment compares favourably with that of ICSI using ejaculated spermatozoa.  相似文献   

5.
OBJECTIVE: To determine whether spermatozoa, located in the seminiferous tubules obtained by needle puncture testicular biopsy, could be cryopreserved successfully within the tubules and subsequently be used for in oocyte fertilization via intracytoplasmic sperm injection (ICSI) after the spermatozoa were removed from the thawed tubules. DESIGN: Clinical case series. SETTING: Private IVF unit. PATIENT(S): Six azoospermic patients (four obstructive, two maturation arrest). MAIN OUTCOME MEASURE(S): Survival rate of thawed spermatozoa, fertilization rate of oocytes after ICSI with spermatozoa extracted from thawed tubules and pregnancies. RESULT(S): All six patients had adequate motile spermatozoa extracted from the thawed tubule sections, and all patients achieved fertilization via ICSI with their partner's eggs. The fertilization rate was 46%, compared with 56% obtained in other previous patient cycles using fresh testicular spermatozoa. Three pregnancies resulted from five ETs. CONCLUSION(S): Cryopreservation and subsequent thawing of seminiferous tubules proved to be a simple and successful method for storage of testicular spermatozoa, reducing the need for repetitive testicular biopsies and increasing the likelihood of sperm availability on the day of oocyte retrieval.  相似文献   

6.
OBJECTIVE: To describe methods of sperm retrieval for intracytoplasmic sperm injection (ICSI) in patients with male factor infertility and to review the clinical results using sperm from the different sources. DESIGN: The literature on sperm-obtaining methods and ICSI was reviewed. Studies related to this topic were identified through MEDLINE. RESULTS(S): This review describes the evolution of sperm retrieval methods. Sperm can be obtained by microepididymal sperm aspiration (MESA), percutaneous sperm aspiration (PESA), and testicular sperm extraction (TESE), from patients with congenital absence of the vas deferens or acquired vas obstruction. When ICSI is performed with ejaculated, epididymal, or testicular sperm, good fertilization and pregnancy rates are achieved without significant differences among the various sperm sources. The original percutaneous sperm aspiration method has been modified slightly and yields successful results. CONCLUSION(S): Viable pregnancies can be achieved with ICSI by using not only ejaculated sperm, but also epididymal and testicular sperm. Microepididymal sperm aspiration, percutaneous sperm aspiration, modified percutaneous sperm aspiration, and testicular sperm extraction can be considered standard procedures to treat male factor infertility.  相似文献   

7.
The first pregnancy achieved in a seronegative woman following in-vitro fecundation through intracytoplasmic sperm (ICSI) injection from a man with autoimmune deficiency syndrome (AIDS; HIV-1 carrier) is reported. The semen was prepared by PureSperm and swim-up techniques. Some of the motile spermatozoa obtained were used to detect the presence of HIV-1 using the polymerase chain reaction technique. HIV-1 in DNA or RNA form was not detected using this technique. The remaining spermatozoa were frozen. Ovarian stimulation in the woman was performed with long-protocol analogues and gonadotrophins. Thirteen mature oocytes were recovered, into which the thawed spermatozoa were microinjected. Nine embryos were obtained. Four were frozen, four transferred and one discarded. The woman became pregnant. Analyses for HIV-1 in the woman, performed in the first and third months of pregnancy, gave negative results. This case provides further experience with washed semen of sufficient quality for performing artificial insemination in HIV-1-serodiscordant couples (101 inseminations, 31 pregnancies, 28 deliveries, 37 babies, all healthy). In women with obstructed Fallopian tubes, or when the semen is not of sufficient quality for artificial insemination techniques to be performed, ICSI can be carried out using frozen, HIV-1-free semen.  相似文献   

8.
The present report covers the results of a 38-month period in which 2853 consecutive intracytoplasmic sperm injection (ICSI) cycles were performed in 1953 couples. These couples were afflicted with male factor infertility and had at least one previous failed conventional in vitro fertilization (IVF) treatment cycle. In other couples, the husband had semen parameters incompatible with conventional IVF or suffered from excretory or secretory azoospermia where it was possible to recover spermatozoa by microsurgical epididymal sperm aspiration (mesa) or by testicular sperm extraction (tese) procedure. Overall, the 2-PN fertilization rate was 62% per retrieved metaphase II oocyte and 70% per successfully injected metaphase II oocyte. Embryo transfer was performed in 91% of started cycles. The cumulative pregnancy rate (positive HCG) was 34% per started ICSI treatment and 37% per embryo transfer.  相似文献   

9.
The authors evaluate their initial experience and results of the technique of microsurgical aspiration of epididymal sperm (MESA) and extraction of testicular sperm (TESE) combined with intracytoplasmic sperm injection into the oocyte (ICSI) in men with azoospermia. The above methods were used in 16 patients with repeatedly assessed azoospermia. Epididymal sperm was obtained in six instances, testicular sperm in 10 instances. With epididymal sperm after ICSI 50% fertilization was achieved after ICSI, with testicular sperm 51% fertilization of oocytes.  相似文献   

10.
This study evaluated different sperm treatments for fertilization of sheep oocytes by intracytoplasmic sperm injection (ICSI) and in vitro fertilization (IVF). In Experiment 1, fresh and frozen semen was separated by Percoll centrifugation and incubated at 30 degrees C or 39 degrees C in HSOF or BSOF medium for 1 h before use for IVF or ICSI. For IVF, oocytes were inseminated and incubated with sperm for 30 min, 4 h and 19 h. Sperm were assessed for acrosome integrity after Percoll centrifugation and 1 h incubation, and those used for IVF were assessed after each period of exposure to the oocytes. Fertilization rates after ICSI were higher for fresh than for frozen-thawed sperm and were highest 19 h after IVF with fresh or frozen-thawed sperm in the presence of HSOF at 30 degrees C. In Experiment 2, fresh semen was separated by Percoll centrifugation and incubated for 5 h in HSOF, and the acrosome reaction was induced with lysophosphatidylcholine. Acrosome integrity was then assessed. Fertilization rates after ICSI were similar for acrosome-reacted and control spermatozoa. These results suggest that induction of the acrosome reaction in spermatozoa before ICSI is unnecessary, whereas a capacitating treatment of spermatozoa is required before IVF.  相似文献   

11.
Two wives of a Muslim with severe male factor infertility had simultaneous intracytoplasmic sperm injection (ICSI) treatments. One wife developed ovarian hyperstimulation syndrome (OHSS), and 19 of 27 oocytes retrieved were subjected to ICSI but only one fertilized; the other wife had a normal response to ovarian stimulation, normal fertilization following ICSI, successful treatment and has recently delivered a live-born infant. The wife who suffered from OHSS has since had another ICSI cycle with a normal response to ovarian stimulation, a normal fertilization rate but no pregnancy. The only variable that determined the different rate of fertilization in the simultaneous ICSI cycles appears to be oocyte quality. While the results of frozen embryo replacement cycles following the decision to freeze all embryos following OHSS is generally satisfactory, it is important to counsel couples about the possible detrimental effects of OHSS on oocyte quality.  相似文献   

12.
Male genital tract obstructions may result from infections, previous inguinal and scrotal surgery (vasectomy) and congenital bilateral absence of the vas deferens (CBAVD). Microsurgery can sometimes be successful in treating the obstruction. In other cases and in cases of failed surgical intervention, the patient can be treated by microsurgical or percutaneous epididymal sperm aspiration (MESA, PESA) or testicular sperm extraction (TESE) and intracytoplasmic sperm injection (ICSI). We present the results of 39 ICSI procedures for obstructive azoospermia in 24 couples. The aetiology of the obstruction was failed microsurgery in 11 patients, CBAVD in nine and genital infections in four. Sperm retrieval was accomplished via MESA in four cases, PESA in 18 cases and via TESE in 11 cases. TESE was only applied when PESA failed to produce enough spermatozoa for simultaneous ICSI. In six patients, the ICSI procedure was performed with cryopreserved spermatozoa after an initial PESA procedure. Fertilization occurred in 47% of the metaphase II oocytes; embryo transfer was performed in 92% of procedures and resulted in a clinical pregnancy in 13/39 procedures. Ongoing pregnancy was achieved in 10/39 procedures. One pregnancy was terminated early after prenatal investigation showed a cytogenetic abnormality (47,XX+18, Edwards syndrome). The other nine pregnancies resulted in the live birth of 10 children, without any congenital abnormalities. Epididymal and testicular retrieved spermatozoa were successfully used for ICSI to treat obstructive azoospermia, and resulted in an ongoing pregnancy in 10 of 24 couples (41.6%) after 39 ICSI procedures, a success rate of 25.6% per treatment cycle and of 27.7% per embryo transfer.  相似文献   

13.
OBJECTIVE: To evaluate and compare sperm quality and suitability for intracytoplasmic sperm injection (ICSI) from open and percutaneous epididymal aspiration in men with obstructive azoospermia, and to determine the relevance of epididymal morphology. PATIENTS AND METHODS: A series of 20 men undergoing vasectomy reversal were evaluated by percutaneous (PESA) and open epididymal sperm aspiration (MESA) before undergoing surgery for reversal. Two samples were taken with PESA, one with the needle in situ (PESA1) and the second while withdrawing the needle (PESA2). Epididymal morphology was graded as normal, distended and grossly distended. Five men undergoing vasectomy served as a control, nonobstructed group for percutaneous aspiration. Analysis of the aspirates was performed immediately after operation with no knowledge of the treatment, and aspiration was considered successful if sperm suitable for ICSI were retrieved. RESULTS: In the obstructed group, 15 of 20 men had successful PESA and 13 of these also had successful MESA. PESA was successful bilaterally eight times compared with MESA on five occasions; two men with successful PESA had no success with MESA. PESA2 was five times more successful than PESA1. Only one PESA in the non-obstructed group was suitable for ICSI. PESA was successful in 21 of 25 distended or grossly distended epididymi compared with only three of 21 non-distended systems. CONCLUSION: PESA is a viable alternative to MESA in patients with obstructive azoospermia, particularly when associated with clinically distended epididymi.  相似文献   

14.
PURPOSE: Our purpose was to evaluate whether the source of spermatozoa influences the results of intracytoplasmic sperm injection (ICSI) treatment in couples with severe male-factor infertility. METHODS: A retrospective analysis of 40 cases of ICSI with testicular-retrieved spermatozoa, matched with 40 cases of ICSI with ejaculated spermatozoa, was performed. We included only couples with normoovulatory females younger than 37 years who were matched according to the day of ovum pickup with the patients in the study group. RESULTS: Eighty cycles were analyzed: 40 cycles using testicular spermatozoa and 40 cycles using ejaculated spermatozoa. In 32 (80%) of the 40 ICSI transcutaneous needle aspiration cycles, we obtained enough spermatozoa to inject all the mature oocytes retrieved. In eight (20%) cases there were not enough spermatozoa to inject all the oocytes. Only 76 (54%) of 141 available oocytes were injected in these eight patients. The oocyte fertilization rates were 42% for the study group and 55.5% for the controls (P < 0.005). Thirty-six (90%) patients in the group with nonobstructive a zoospermia (NOA) and 37 (92.5%) patients in the oligoteratoasthenospermia (OTA) group had embryos for replacement. The mean cleavage rates per cycle (96% with testicular and 93% with ejaculated spermatozoa), the mean number of embryos per transfer (3.72 +/- 1.6 in the NOA group and 4.24 +/- 1.5 in the OTA group), the embryo quality (cumulative embryo scoring = 34.03 +/- 22.62 in the testicular sperm group and 36.08 +/- 19.28 in the ejaculated sperm group), and the clinical pregnancy rates (22.5% in the NOA patients and 20% in the ejaculate group) were not significantly different between groups. CONCLUSIONS: High fertilization, cleavage, and pregnancy rates can be achieved with intracytoplasmic testicular sperm injection from patients with NOA, reaching levels comparable with those of ICSI using ejaculated spermatozoa.  相似文献   

15.
Recovery of motile spermatozoa from extremely low quality samples for use in the intracytoplasmic sperm injection (ICSI) procedure is difficult. To solve this problem we developed a simple method to recover the motile spermatozoa using a 3% polyvinylpyrrolidone (PVP) droplet. After depositing a sperm pellet into this slightly viscous droplet, motile spermatozoa readily swam out to the clear area while immotile spermatozoa dispersed to a lesser extent, so that motile and immotile cells became clearly separated from each other. A total of 36 ICSI cycles using spermatozoa with extremely low quality characteristics were performed. We recovered the motile spermatozoa from all sperm samples from two sources of poor quality spermatozoa. Thirty-one cycles of ICSI with ejaculate resulted in fertilization and pregnancy rates of 54 and 29% respectively. Five cycles of ICSI with frozen-thawed epididymal spermatozoa resulted in fertilization and pregnancy rates of 70 and 60% respectively. The 3% PVP droplet method is very simple and easy to perform, so it may be useful for recovering the motile spermatozoa from extremely low quality sperm samples used for ICSI.  相似文献   

16.
Thirty-three patients with azoospermia of apparently excretory origin underwent surgery for epididymis-deferens anastomosis and/or epididymal sperm puncture. Pathology examinations of the epididymal fluid and biopsies of the testicles or epididymis were performed at surgery. Based on the clinical presentation, sperm results and per-operative findings, patients were divided into six groups by etiology: idiopathic azoospermia (n = 5), post-infectious azoospermia (n = 15), agenesia of the excretory (n = 6) or secretory (n = 3) ducts, vasectomy (n = 2), and obstruction of the ejaculatory ducts (n = 2). Peroperative identification of spermatozoa at epididymal puncture or biopsy was statistically more frequent in patients with agenesis of the excretory ducts than in patients with post-infectious or idiopathic azoospermia. Biopsies of the testicle led to the diagnosis of secretory azoospermia in 3 cases and revealed a functional parenchyma in all the other groups of patients. Epididymis-deferens anastomosis was performed in 45% of the cases and was successful in 13%. Rate of fertility with the intracytoplasmic sperm injection was 33%; there was no difficulty in using fresh or frozen sperm. Clinical pregnancy was continued to term with frozen sperm. This study confirms that testicular function is preserved in excretory azoospermia. With or without epididymis-deferens anastomosis, epididymal spermatozoa can generally be preserved for later use. Couples should however be counselled on the delays to contraception which may vary from months to years.  相似文献   

17.
High success rates have been reported for the use of intracytoplasmic sperm injection (ICSI) in alleviating essentially andrological infertility. However, neither the relationship between any of the sperm parameters and the result of ICSI nor the minimal sperm requirements for ICSI have been investigated so far. In this paper, our objective was therefore to study the relationship between three basic sperm parameters (total sperm count, sperm motility and morphology) and the outcome of ICSI by retrospective analyses of fertilization, embryo development and pregnancy rates in 966 micro-injection cycles, performed with ejaculated semen. The results showed that there was no important influence from either the type or the extent of sperm impairment on the outcome of ICSI. Even in the most extreme cases of male-factor infertility, where cryptozoospermia or total astheno- or total teratozoospermia was diagnosed in the initial semen sample, high fertilization and pregnancy rates were obtained by ICSI. Only one condition had a strongly negative influence on the result of ICSI: where an immotile (presumably dead) spermatozoon was injected into the oocyte. Thus the only ultimate criterion for successful ICSI is the presence of at least one living spermatozoon per oocyte in the pellet of the treated semen sample used for micro-injection.  相似文献   

18.
OBJECTIVE: To report a triplet pregnancy that occurred after intracytoplasmic injection of sperm into cryopreserved oocytes. DESIGN: Case report. SETTING: Instituto de Ginecología y Fertilidad (IFER), Buenos Aires, Argentina. PATIENT: A 36-year-old infertile patient with premature ovarian failure and a previous term pregnancy with fresh donated oocytes. INTERVENTION(S): We administered leuprolide acetate for pituitary down-regulation followed by E2 valerianate in incremental doses until an endometrial lining of >8 mm was observed by ultrasound. Thawing of frozen donated oocytes, intracytoplasmic sperm injection (ICSI), and translaparoscopic fallopian tube ET also were performed. Natural micronized progesterone was administered intravaginally (600 mg/d) before ET. MAIN OUTCOME MEASURE(S): Ultrasound at the 8th week of gestation revealed a triplet pregnancy with active fetal heartbeats. RESULT(S): A triple intrauterine gestation was achieved with the use of microinjection into cryopreserved oocytes. CONCLUSION(S): This case illustrates the feasibility of oocyte cryopreservation for clinical use in the era of ICSI.  相似文献   

19.
Testicular or epididymal spermatozoa were obtained for in-vitro fertilization and intracytoplasmic sperm injection (ICSI) in 27 cycles out of 33 (in six men the azoospermia proved to have testicular causes). Testicular needle biopsy carried out in addition to surgical open biopsy proved to be an effective method to obtain spermatozoa for ICSI from patients with obstructive azoospermia. Thus it might be possible to replace scrotal operations by simple needle biopsies. Embryos resulting from ICSI with testicular spermatozoa were used in 19 transfers that resulted in six pregnancies. One pregnancy resulted from six embryo transfers from ICSI after microsurgical-epididymal sperm aspiration (MESA). The normal fertilization rates with testicular (37.3%) and MESA spermatozoa (53.7%) did not differ significantly from each other, but with testicular spermatozoa the rate was significantly lower than that obtained with ejaculated spermatozoa and ICSI (59.7%) in the matched couples. The abnormal fertilization of oocytes with one pronucleus was significantly higher with testicular spermatozoa than with ejaculated spermatozoa in the control couples.  相似文献   

20.
Factors other than spermatozoa could be the major determinant of the success of assisted reproduction treatment in cases of male infertility. Our aim was to evaluate the effect of the wife's age and ovarian reserve on assisted reproduction success rates in the most severe type of male infertility, i.e. azoospermia. A total of 249 consecutive couples suffering from male infertility caused by azoospermia underwent microsurgical epididymal sperm aspiration (MESA) or testicular sperm extraction (TESE) with intracytoplasmic sperm injection (ICSI). Of these men, 186 had irreparable obstructive azoospermia, and 63 had non-obstructive azoospermia due to testicular failure. Neither the pathology, the source, the quantity, nor the quality of spermatozoa had any effect on fertilization or pregnancy rates. Maternal age and ovarian reserve (number of eggs) had no effect on fertilization or embryo cleavage, but did dramatically affect the embryo implantation, pregnancy and delivery rates. Wives of azoospermic men who were in their 20s had a 46% live delivery rate per cycle, wives aged 30-36 years had a 34% live delivery rate per cycle, wives aged 37-39 years had a 13% live delivery rate per cycle, and wives > or = 40 years had only a 4% live delivery rate per cycle. The number of eggs retrieved also affected pregnancy and delivery rate, but to a lesser extent than age. In virtually all cases of obstructive azoospermia, and in 62% of cases with non-obstructive azoospermia caused by germinal failure, sufficient spermatozoa could be retrieved to perform ICSI, with normal fertilization and embryo cleavage. However, the pregnancy rate and the live delivery rate were dependent strictly on the age of the wife, and on her ovarian reserve. Unfortunately, exaggerated claims of high pregnancy rates can thus easily be made by manipulating, in a very simple way, selection for female factors.  相似文献   

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