Can you ever collect too many oocytes?

STUDY QUESTION: Does the chance of pregnancy keep improving with increasing number of oocytes, or can you collect too many? SUMMARY ANSWER: Clinical pregnancy (CP) and live birth (LB) rates per embryo transfer varied from 10.2 and 9.2% following one oocyte collected to 37.7 and 31.3% when >16 oocytes were collected. Regression modelling indicated success rates increased or at least stayed the same with number of oocytes collected. WHAT IS KNOWN ALREADY: It has been suggested that if >15 oocytes are collected, the success rate for fresh embryo transfers decreases. As this is counterintuitive, as more oocytes should result in more embryos, with a better choice of quality embryos, we decided to analyse the recent experience in a busy IVF unit. STUDY DESIGN, SIZE DURATION: A retrospective analysis of clinical pregnancy and live birth outcome, with respect to number of oocytes collected at Monash IVF for the 2-year period between August 2010 and July 2012, where patients under the age of 45 years underwent a fresh embryo transfer. This included 7697 stimulated cycles for IVF and ICSI. PARTICIPANT/MATERIALS, SETTING, METHODS: Statistical analysis involved data tables and graphs comparing oocyte number with outcome. Results of women who had their first oocyte collection with an embryo transfer within the reference period were analysed by logistic regression analysis including other covariates that might influence pregnancy outcome. Analysis was also carried out of all the 7679 oocyte collections undertaken, resulting in fresh embryo transfers by generalized estimating equations to allow for the within subject correlation in outcomes for repeated treatments. MAIN RESULTS AND THE ROLE OF CHANCE: The number of oocytes collected varied from 1 to 48. Clinical pregnancy and live birth rates per embryo transfer varied from 10.2 and 9.2% when only one oocyte was collected to 37.7 and 31.3% when >16 oocytes were collected. Regression modelling indicated success rates increased or at least stayed the same or with the number of oocytes collected. The percentage of women with embryos cryopreserved increased from under 20% with <4 oocytes collected to over 70% with >16 oocytes collected. There was a slight increase (from 18 to 22%) in oocyte immaturity and a more marked increase (from 0 to 3%) in cancelling fresh transfers to prevent Ovarian Hyperstimulation Syndrome (OHSS) with increase in number of oocytes collected above 16. The results of this study suggest that you cannot collect too many oocytes as both clinical pregnancy and live birth rates do not decrease with high numbers of oocytes collected. However, once >15 oocytes are collected, everything gets quite uncertain. LIMITATIONS, REASONS FOR CAUTION: As the data become sparse above 15 oocytes, we could not demonstrate a significant increase in pregnancy rates above this number. Larger studies would be required to answer the question whether there is a plateau, or rates continue to increase. The negative of aggressive stimulation to produce many oocytes is that the risk of OHSS increases, and this is the most serious complication of ovarian stimulation. STUDY FUNDING/COMPLETING OF INTERESTS: No funding was required. There is no conflict of interest, except that G.K., V.M. and C.M. are shareholders in Monash IVF Pty Ltd.

Defective protein kinase A and C pathways are common causes of disordered zona pellucida (ZP)--induced acrosome reaction in normozoospermic infertile men with normal sperm-ZP binding.

OBJECTIVE: To determine association between defective protein kinases C (PKC) and A (PKA) and disordered zona pellucida (ZP)-induced acrosome reaction (DZPIAR) in normozoospermic infertile men with normal sperm-ZP binding. DESIGN: Sperm from DZPIAR infertile men were treated without (control) or with (test) phorbol myristate acetate (PMA, PKC activator) or dibutyryl cyclic AMP (dbcAMP, PKA activator) under in vitro standard culture condition. The ZP-induced AR was assessed and compared between control and test. SETTING: Public and private hospital-based clinical assisted reproduction technology (ART) centers. PATIENT(S): A total of 51 DZPIAR infertile men were involved in this study. INTERVENTION(S): None. MAIN OUTCOMES MEASURE(S): Sperm-ZP binding and the ZP-induced IAR. RESULT(S): Both PMA and dbcAMP enhanced ZP-induced AR up to a normal level (≥25%) in some subjects with DZPIAR: 29 (57%) with PMA and 27 (53%) with dbcAMP. Overall 35 (69%) had the ZP-induced AR enhanced to normal by PMA or dbcAMP but 16 (31%) had little or no response to either agent. Fourteen men responded to the two activators differently: 8 effective only with PMA and 6 effective only with dbcAMP. CONCLUSION(S): Defective upstream of PKC and PKA pathways are highly associated with disordered ZPIAR in normozoospermic infertile men with normal sperm-ZP binding.

Quinn's advantage fertilization medium enhances zona pellucida-induced acrosome reaction compared with human tubal fluid medium.

The aim of this study was to compare sperm velocity, hyperactivation, zona pellucida (ZP) binding and ZP-induced acrosome reaction (AR) between Quinn's advantage fertilization (QAF), human tubal fluid (HTF) and Ham's F10 media. Semen samples were obtained from normozoospermic men and motile spermatozoa were prepared by gradient centrifugation (PureSperm). Unfertilized oocytes from clinical IVF were used for spermatozoa-oocyte interaction tests. Sperm velocity and hyperactivation were assessed using a Hamilton-Thorn motility analyser. When media were supplemented with human albumin, sperm motility and velocity and sperm binding were not significantly different between QAF and HTF. However, ZP-induced AR was significantly higher with QAF than HTF (42±22 versus 21±18, P<0.th001). Sperm velocity, hyperactivation and sperm binding were also significantly higher in QAF than Ham's F10 media. Supplementation of media with either human serum or human albumin showed no difference in effect on all sperm test results. In conclusion, QAF medium significantly enhances ZP-induced AR which is essential for sperm penetration. Thus QAF appears to be a better medium than HTF for sperm fertilizing ability in conventional IVF.

Adverse obstetric and perinatal outcomes in subfertile women conceiving without assisted reproductive technologies.

OBJECTIVE: To determine whether adverse perinatal outcomes are increased in subfertile women. DESIGN: Cohort study. SETTING: Two tertiary assisted reproductive technologies (ART) centers; Victorian births register. PATIENT(S): Records of women who registered with the clinics (1991-2000), but did not have an infant using ART, were linked to the birth register (1991-2004) to identify singleton non-ART births within 5 years of registration (N = 2171). Controls, matched by maternal age and year of infant's birth, were selected randomly from birth records (N = 4363). INTERVENTIONS: None. MAIN OUTCOME MEASURE(S): Adverse obstetric and perinatal outcomes. RESULT(S): After adjusting for confounders, compared with controls, subfertile women had increased odds of hypertension or preeclampsia (adjusted odds ratio [OR] 1.29, 1.02-1.61), antepartum hemorrhage (adjusted OR 1.41, 1.05-1.89), perinatal death (adjusted OR 2.19, 1.10-4.36), low birth weight (adjusted OR 1.44, 1.11-1.85), preterm birth <37 weeks (adjusted OR 1.32, 1.05-1.67) or <31 weeks (adjusted OR 2.37, 1.35-4.13), and cesarean delivery (adjusted OR 1.56, 1.37-1.77). There was weak evidence for increased birth defects (adjusted OR 1.30, 0.98-1.72) and gestational diabetes (adjusted OR 1.25, 0.96-1.63). No increased risk was found for prelabor rupture of membranes, small for gestational age, or postpartum hemorrhage. CONCLUSION(S): Subfertile women with singleton births are at increased risk of several adverse outcomes. These risks should be considered during their antenatal care and when analyzing adverse effects of ART.

Increased risk of blastogenesis birth defects, arising in the first 4 weeks of pregnancy, after assisted reproductive technologies.

BACKGROUND: The reasons for increased birth defect prevalence following in-vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) are largely unknown. Classification of birth defects by pathology rather than organ system, and examination of the role of embryo freezing and thawing may provide clues to the mechanisms involved. This study aimed to investigate these two factors. METHOD: Data on 6946 IVF or ICSI singleton pregnancies were linked to perinatal outcomes obtained from population-based data sets on births and birth defects occurring between 1991 and 2004 in Victoria, Australia. These were compared with 20,838 outcomes for singleton births in the same population, conceived without IVF or ICSI. Birth defects were classified according to pathogenesis. RESULTS: Overall, birth defects were increased after IVF or ICSI [adjusted odds ratio (OR) 1.36; 95% CI: 1.19-1.55] relative to controls. There was no strong evidence of risk differences between IVF and ICSI or between fresh and thawed embryo transfer. However, a specific group, blastogenesis birth defects, were markedly increased [adjusted OR 2.80, 95% CI: 1.63-4.81], with the increase relative to the controls being significant for fresh embryo transfer (adjusted OR 3.65; 95% CI: 2.02-6.59) but not for thawed embryo transfer (adjusted OR 1.60; 95% CI: 0.69-3.69). CONCLUSION: Our findings suggest that there is a specific risk of blastogenesis birth defects arising very early in pregnancy after IVF or ICSI and that this risk may be lower with use of frozen-thawed embryo transfer.

Comparison of outcomes of conventional intracytoplasmic sperm injection and intracytoplasmic sperm injection using sperm bound to the zona pellucida of immature oocytes.

This study was to compare the outcomes of conventional (scientist-selected sperm) intracytoplasmic sperm injection (ICSI) and a modified ICSI using zona pellucida (ZP)-bound sperm. Although with 39 couples in each group there was no statistical significance in fertilization, embryo development, implantation, and fetal heart clinical pregnancy rates, the higher implantation and clinical pregnancy rates with ZP-bound sperm encourages further evaluation with larger numbers of subjects using sibling oocytes to determine if the ZP-bound sperm are biologically and functionally superior.

World Health Organization reference values for human semen characteristics.

BACKGROUND: Semen quality is taken as a surrogate measure of male fecundity in clinical andrology, male fertility, reproductive toxicology, epidemiology and pregnancy risk assessments. Reference intervals for values of semen parameters from a fertile population could provide data from which prognosis of fertility or diagnosis of infertility can be extrapolated. METHODS: Semen samples from over 4500 men in 14 countries on four continents were obtained from retrospective and prospective analyses on fertile men, men of unknown fertility status and men selected as normozoospermic. Men whose partners had a time-to-pregnancy (TTP) of < or =12 months were chosen as individuals to provide reference distributions for semen parameters. Distributions were also generated for a population assumed to represent the general population. RESULTS: The following one-sided lower reference limits, the fifth centiles (with 95th percent confidence intervals), were generated from men whose partners had TTP < or = 12 months: semen volume, 1.5 ml (1.4-1.7); total sperm number, 39 million per ejaculate (33-46); sperm concentration, 15 million per ml (12-16); vitality, 58% live (55-63); progressive motility, 32% (31-34); total (progressive + non-progressive) motility, 40% (38-42); morphologically normal forms, 4.0% (3.0-4.0). Semen quality of the reference population was superior to that of the men from the general population and normozoospermic men. CONCLUSIONS: The data represent sound reference distributions of semen characteristics of fertile men in a number of countries. They provide an appropriate tool in conjunction with clinical data to evaluate a patient's semen quality and prospects for fertility.

Relationship between seminal plasma zinc concentration and spermatozoa-zona pellucida binding and the ZP-induced acrosome reaction in subfertile men.

The aim of this study was to determine the relationship between seminal zinc concentration and spermatozoa-zona pellucida (ZP) binding and the ZP-induced acrosome reaction (ZPIAR) in subfertile men. Semen analyses and seminal zinc concentration assessments were carried out according to the World Health Organization manual for 458 subfertile men. A spermatozoa-ZP interaction test was carried out by incubating 2 x 10(6) motile spermatozoa with a group of four unfertilized oocytes obtained from a clinical in vitro fertilization programme. After 2 h of incubation, the number of spermatozoa bound per ZP and the ZPIAR of ZP-bound spermatozoa were examined. The effect of adding 0.5 mmol L(-1) zinc to the media on the ZPIAR of spermatozoa from normozoospermic men was also tested in vitro. Seminal zinc concentration positively correlated with sperm count and duration of abstinence, but negatively correlated with semen volume. On analysis of data from all participants, both spermatozoa-ZP binding and the ZPIAR were significantly correlated with sperm motility and normal morphology, but not with seminal zinc concentration. However, in men with normozoospermic semen, the seminal zinc concentration was significantly higher in men with defective ZPIAR (< 16%) than in those with normal ZPIAR (>or= 16%) (P < 0.01). The addition of 0.5 mmol L(-1) zinc to the culture media had no effect on spermatozoa-ZP binding, but significantly reduced the ZPIAR in vitro (P < 0.001). In conclusion, seminal zinc concentration is correlated with sperm count and the duration of abstinence in subfertile men. In men with normozoospermic semen, high seminal zinc concentration may have an adverse effect on the ZPIAR.

Induction of spermatogenesis and fertility during gonadotropin treatment of gonadotropin-deficient infertile men: predictors of fertility outcome.

BACKGROUND: The induction of spermatogenesis and fertility with gonadotropin therapy in gonadotropin-deficient men varies in rate and extent. Understanding the predictors of response would inform clinical practice but requires multivariate analyses in sufficiently large clinical cohorts that are suitably detailed and frequently assessed. DESIGN, SETTING, AND PARTICIPANTS: A total of 75 men, with 72 desiring fertility, was treated at two academic andrology centers for a total of 116 courses of therapy from 1981-2008. OUTCOMES: Semen analysis and testicular examination were performed every 3 months. RESULTS: A total of 38 men became fathers, including five through assisted reproduction. The median time to achieve first sperm was 7.1 months [95% confidence interval (CI) 6.3-10.1]) and for conception was 28.2 months (95% CI 21.6-38.5). The median sperm concentration at conception for unassisted pregnancies was 8.0 m/ml (95% CI 0.2-59.5). Multivariate correlated time-to-event analyses show that larger testis volume, previous treatment with gonadotropins, and no previous androgen use each independently predicts faster induction of spermatogenesis and unassisted pregnancy. CONCLUSIONS: Larger testis volume is a useful prognostic indicator of response. The association of slower responses after prior androgen therapy suggests that faster pregnancy rates might be achieved by substituting gonadotropin for androgen therapy for pubertal induction, although a prospective randomized trial will be required to prove this.

Assessing the health and development of ART-conceived young adults: A study of feasibility, parent recall, and acceptability.

BACKGROUND: Assisted reproductive technologies (ART) to treat infertility have been available for nearly three decades. There have been a number of systematic comparisons of the health and development of ART-conceived with spontaneously-conceived (SC) children. Data are equivocal, some finding no differences and others that there are more health and developmental problems in the ART group. It is agreed that perinatal mortality and morbidity are worse after assisted than spontaneous conception and the impact of the hormonally altered intrauterine environment on puberty and later fertility of offspring are unknown. To date however, there has been no investigation of the health and development of ART-conceived young adults, including from the world's few prospective cohorts of ART conceived children. Obtaining these data requires contact to be made with people at least twenty years after discharge from the treating service. Given the ethical difficulties of approaching families to participate in research up to two decades after cessation of treatment, the aim of this exploratory qualitative investigation was to assess the feasibility and acceptability of approaching mothers treated for infertility prior to 1988, and their recall of the health and development of their ART-conceived young adult children. METHODS: Mothers treated for infertility at the Royal Women's Hospital Reproductive Biology Unit in Melbourne, Australia prior to 1988 were approached by a senior clinician and invited to participate in individual semi-structured interviews which could include their partners and/or young adult children if they wished. Recruitment continued until theoretic saturation had been reached. RESULTS: Ten mothers, two of their husbands and five young adults participated in interviews, and the health and development of 15 ART-conceived young adults were described. The experience of conception, pregnancy, birth and the health and development of the children were recalled vividly and in detail. Families were pleased to have been approached and supported the need for systematic data collection. Mode of conception had been disclosed from childhood to all the offspring. CONCLUSION: With careful and sensitive recruitment strategies it is feasible and acceptable to contact women treated for infertility at least two decades ago and their families, to assess the health and development of ART-conceived young adults.

Comparison of the frequency of defective sperm-zona pellucida (ZP) binding and the ZP-induced acrosome reaction between subfertile men with normal and abnormal semen.

BACKGROUND: The aim of this study was to compare the frequency of defective sperm-zona pellucida (ZP) binding (DSZPB) and defective ZP-induced acrosome reaction (DZPIAR) in subfertile men (i.e. male partners of infertile couples) with normal and abnormal semen analyses. METHODS: A total of 1030 subfertile men with normal semen analysis (n=255), oligozoospermia (count<20x10(6)/ml, n=136), severe teratozoospermia (strict normal morphology

[Assessment of human sperm function and clinical management of male infertility].

In this article, we provide an update review on the implication of the assessment of human sperm function and the management of male infertility in clinical assisted reproductive technology (ART) known as in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI). In most ART clinics, the assessment of male fertility is still mainly based on routine semen analysis but it is inaccurate in predicting sperm fertilizing ability. Thus it is often difficult to determine if IVF or ICSI will be an optimal treatment for patients in the initial cycle. Before introduction of ICSI, frequency of low ( <30%) fertilization rate in IVF was very high (20-35% of patients). Evidence suggests that sperm defects are the major contributors to complete failure of fertilization in IVF. Most common sperm defects are oligozoospermia, asthenozoospermia and teratozoospermia though many of the patients are shown to be normal in routine semen analysis. In the literature, many new sperm function tests have been developed, including sperm DNA normalities assessed by Acridine Orange (AO), sperm-zona pellucida (ZP) binding, the ZP-induced acrosome reaction (AR) , sperm-ZP penetration and recently hyaluronan binding assay (HBA). For routine semen analysis, sperm morphology is one of the most useful values for the prediction of sperm function but is also the most difficult test to perform accurately and consistently. Oocytes that failed to fertilize in clinical IVF/ICSI are valuable biological materials for testing sperm function. The human ZP selectively binds sperm with normal morphology and an intact acrosome. The ZP-induced AR is highly correlated with sperm-ZP penetration and disordered ZP-induced AR causes infertility in about 25% men with unexplained infertility with normal semen analysis. Both oligozoospermic (sperm count < 20 x 10(6) /ml) and severe teratozoospermia (strict normal sperm morphology < or =5%) men have a very high ( >70%) frequency of defective sperm-ZP interaction. Thus patients with defects of sperm-ZP interaction should be identified and treated with ICSI since they have high risk of low or zero fertilization rate in IVF. HBA test highly correlates with sperm motility and normal morphology but provides no additional information about sperm fertility. Clinical value of sperm DNA normalities detected by AO for the prediction of ART outcomes is currently still inconclusive and requires further investigation. In conclusion, addition of some of these new sperm tests to routine semen analysis could significantly improve the management of male infertility in clinical ART.

Relationships between timing of syngamy, female age and implantation potential in human in vitro-fertilised oocytes.

Although early developmental markers are frequently used to select embryos for transfer in human assisted reproduction, their value as independent predictors of outcome is often unclear. In this study, the value of using early syngamy and first cleavage as predictors of implantation potential of Day 2 embryos was investigated by examining their interrelationships with subsequent development, female age and implantation. Implantation rates were higher when syngamy occurred before 23-24 h post insemination even when all embryos analysed were transferred 42 h post insemination at the 4-cell stage (25.8 v. 11.9% for the later syngamy group; P < 0.01). Although there was a significant (r = 0.682; P < 0.001) relationship between earlier entry into syngamy and female age, earlier syngamy was still associated with a significantly higher implantation rate in Day 2 embryos with four blastomeres in women under 36 years of age (31.4 v. 15.4% for the later syngamy group; P < 0.05). The ability of timing of syngamy to predict implantation independent of other variables was confirmed by multiple logistic regression analysis. Although related to both subsequent embryo development and female age, early entry into syngamy is a predictor of implantation potential independent of both correlates in human Day 2 in vitro-fertilised embryos.

Recovery of human sperm motility and ability to interact with the human zona pellucida after more than 28 years of storage in liquid nitrogen.

Six donor semen samples were evaluated after 28 years cryopreservation in liquid nitrogen. The results showed that the samples retained good postthaw motility recovery and normal levels of binding to the human zona pellucida and that four of the five samples tested also gave normal levels of zona-induced acrosome reaction. In conclusion, human sperm can survive very long-term storage, which is pertinent information for clinicians referring boys and young men for sperm banking before chemotherapy.

Assisted conception is a risk factor for postnatal mood disturbance and early parenting difficulties.

OBJECTIVE: To investigate whether assisted conception is associated with an increased risk of admission to a residential early parenting program for treatment of maternal mood disorder or infant feeding or sleeping disorders in the postpartum year. DESIGN: Systematic audit of consecutive medical records. SETTING: Masada Private Hospital Mother Baby Unit (MPHMBU), Melbourne, Australia. PATIENT(S): Medical records of all mother-infant dyads admitted to MPHMBU between July 2000 and August 2002. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Modes of conception and delivery of index infant, maternal and infant age on admission, multiplicity of birth, infant birth weight, and Edinburgh Postnatal Depression Scale scores. RESULT(S): A total of 745 records were audited, and mode of conception was recorded in 526 (70.6%) of records. Overall 6% (45/745) of the admitted infants had been conceived through assisted reproductive technologies compared with 1.52% in the general population (relative risk 4.0; 95% confidence interval, 3.0-5.4). Mothers who had conceived with assisted reproductive technologies were older and more likely to have had cesarean and multiple births than those who conceived spontaneously. CONCLUSIONS: Assisted conception appears to be associated with a significantly increased rate of early parenting difficulties. Women who experience assisted conception may require additional support before and after their babies are born.

Clinical application of sperm-oocyte interaction tests in in vitro fertilization--embryo transfer and intracytoplasmic sperm injection programs.

OBJECTIVE: To review the clinical value of sperm-oocyte interaction tests for the diagnosis and management of infertility by standard IVF or intracytoplasmic sperm injection (ICSI). DESIGN: Review of recent publications on relationships among sperm-oocyte interaction tests, sperm characteristics, and results of IVF and determination of frequency of defective sperm-oocyte interaction in infertile men. MAIN OUTCOME MEASURE(S): Fertilization rates with IVF, sperm characteristics, sperm-zona pellucida (ZP) binding, ZP-induced acrosome reaction (AR), and sperm-ZP penetration. RESULT(S): Sperm defects associated with low sperm-ZP binding or impaired ZP-induced AR and sperm-ZP penetration are the major causes of failure of fertilization when all or most oocytes from a couple do not fertilize in standard IVF. There is a high frequency of defective sperm-ZP interaction in men with oligozoospermia (<20 x 10(6)/mL) and severe teratozoospermia (strict normal sperm morphology < or =5%). Sperm morphology correlates with sperm-ZP binding, and sperm concentration correlates with ZP-induced AR in infertile men with sperm concentrations >20 x 10(6)/mL. Defective ZP-induced AR may cause infertility in up to 25% men with idiopathic infertility. These patients require ICSI despite the normal standard semen analyses. CONCLUSION(S): Sperm-oocyte interaction tests are useful for diagnosis of subtle sperm defects that cause infertility in men without severe abnormalities of semen analysis. Pre-IVF diagnosis of these sperm defects will assist in the clinical assignment of patients to treatment with either standard IVF or ICSI.

Flow cytometry and microscopic acridine orange test: relationship with standard semen analysis.

Improved prediction of male fertility requires advances in semen analysis. This study examined the reproducibility and independence of the flow cytometry acridine orange test (FCM-AOT) of sperm chromatin integrity as an assessment of semen quality. The study found that FCM-AOT results are not significantly affected by up to 6 h delay in semen preparation (n = 9) or contamination of semen with moderate concentrations of bacteria (<10(8)/ml E. coli or Staph. epidermidis, n = 14). The variation of replicate measurements within samples was low (%Abnormal alpha(t): SD = 1.4, 95%CI = 4.6, n = 25) and different samples from the same men were mostly within the range of measurement error (n = 35). FCM-AOT variables, in particular %Abnormal alpha(t), displayed significant correlations with motility (r = -0.557), vitality (r = -0.469) and morphology (r = -0.464, n = 201), which are similar in magnitude to those existing between the standard semen variables. Surprisingly, no correlation was found between %Abnormal alpha(t) and the microscopic acridine orange test (M-AOT) (n = 185), suggesting the FCM results are sensitive to a different aspect of sperm quality. In summary, this study confirms that although not totally independent of standard semen analysis or the M-AOT, it is found to be a robust, sensitive and reproducible measure of semen quality, representative of the individual.

High frequency of defective sperm-zona pellucida interaction in oligozoospermic infertile men.

BACKGROUND: The ability of sperm to interact with the zona pellucida (ZP) plays a critical role during the process of human fertilization. The aim of this study is to determine frequency of defective sperm-ZP interaction in oligozoospermic infertile men. METHODS: Sperm-ZP binding assays and the ZP-induced acrosome reaction (AR) were performed in 72 infertile men with a sperm concentration <20 x 10(6)/ml. Oocytes that had previously failed to fertilize in a clinical IVF programme were used for the tests. Motile sperm (2 x 10(6)/ml) selected by swim-up from each semen sample were incubated with four oocytes for 2 h. The number of sperm bound per ZP and the ZP-induced AR were assessed. Under these conditions, an average of < or =40 sperm bound/ZP was defined as low sperm-ZP binding and a ZP-induced AR < or =16% was defined as low ZP-induced AR. RESULTS: In the 72 oligozoospermic men, 28% (20/72) had low sperm-ZP binding. Of those with normal sperm-ZP binding, 69% (36/52) had low ZP-induced AR. Overall, 78% (56/72) had either low ZP-binding or normal ZP binding but low ZP-induced AR. This means that only 22% (16/72) had both normal sperm-ZP binding and normal ZP-induced AR. CONCLUSION: Oligozoospermic men have a very high frequency of defective sperm-ZP interaction, consistent with their low natural fertility or low fertilization rate in conventional IVF. Infertile couples with oligozoospermic semen should be treated by ICSI rather than by conventional IVF.

Comparison of sperm counts in two groups of men presenting for infertility investigations 20 years apart.

Aims: To compare sperm counts for two groups of men who had presented for infertility investigations approximately 20 years apart. Methods: The study compared results for 309 men tested between 1977 and 1981 with those of 559 men tested between 1997 and 1998 using identical methodology. In order to approximate the normal population, only those men with counts above 5 million/mL were included in the final analysis. Bias, due to repeated testing after an initial abnormal result, was minimized by including only the patient's first test results. In addition, to allow for time-dependent changes in the requirements for semen samples, results were included only if a complete sample was produced by masturbation after 3-5 days abstinence. Results: There was a small, but statistically significant drop in ejaculate volume (3.9-3.6 mL, P = 0.015) and a significant increase in the patient's mean age (32.18 vs 35.08, P < 0.001). Both groups had median abstinence of 3 days and no difference in sperm counts with a mean (median) count for the early group of 87.9 (75) versus 92.0 (76) for the recent group (P > 0.80). The significant drop in ejaculate volume was not reflected in a difference (P = 0.45) in total sperm numbers in the ejaculate with 320.7 (255) versus 313.1 (234). Conclusion: This study found no evidence of a decrease in sperm counts or total sperm output in men (excluding those with severe oligospermia) presenting for infertility investigations in Melbourne, Australia, over the last two decades of the twentieth century. (Reprod Med Biol 2004; 3: 211-216).