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PubMed1999

The fertility impact of changes in the timing of childbearing in the developing world.

This study examines the role of tempo effects in the fertility declines of less developed countries. These effects temporarily inflate the total fertility of a population during periods when the age at childbearing declines and deflate it when childbearing is postponed. An analysis of data from the World Fertility Surveys and the Demographic and Health Surveys demonstrates that fertility trends observed in many less developed countries are likely to be distorted by changes in the timing of childbearing. In most countries women are delaying childbearing, which implies that observed fertility is lower than it would have been without tempo changes. This pattern is most clearly documented in Taiwan, where accurate birth statistics from a vital registration system make it possible to estimate the tempo components of fertility annually from 1978 to 1993. The small but unexpected rise in the total fertility of Colombia in the early 1990s is attributed to a decline in the negative tempo distortion that prevailed in the 1980s. Similar interruptions of ongoing fertility declines may occur in the future in other countries when existing negative tempo effects are removed.

Colombia↗
PubMed2005

Influence of visible light and ultraviolet irradiation on motility and fertility of mammalian and fish sperm.

OBJECTIVE: The effects of visible light irradiation on sperm motility, fertility, and reactive oxygen species (ROS) formation were investigated and compared in ram and fish (tilapia). BACKGROUND DATA: Low-energy visible light has previously been found to modulate various processes in different biological systems. In the literature, it is accepted that the first step following visible light irradiation is the formation of ROS by endogenous cellular photosensitizers. METHODS: Sperm of ram and tilapia were irradiated with various light sources (400-800 nm white light, 660 nm red light, 360 nm blue light, 294 nm UV), and their motility and fertility rates were measured. The amount of ROS generated by irradiation was estimated using electron paramagnetic resonance (EPR) technique. RESULTS: Sperm taken from tilapia showed higher motility and fertility following red and white light irradiation. In contrast, the motility and fertility of ram sperm were slightly increased only by red light. A negative effect on motility and fertility of sperm of both species was obtained following irradiation with UV and blue light. The amount of ROS produced in irradiated tilapia sperm was much higher than that of ram sperm. CONCLUSIONS: The results show that different wavelengths differentially affect tilapia and ram sperm motility and fertilization. The difference in response to the various light sources might be explained by the different amounts of ROS formation by ram and tilapia, which are in agreement with the physiology of fertilization appropriate to each of these species. Based on these results, it is suggested that in vitro fertilization in mammals should be performed in darkness or at least under red light.

Animals↗
PubMed1986

A numerical simulation of the one-locus, multiple-allele fertility model.

Numerical simulations were performed to determine the equilibrium behavior of the one-locus fertility model in which fitness is considered as a property of a pair of mating diploids. A series of patterns of "fertility matrices" were considered for a single locus with two to six alleles. From these simulations, 19 different statistics were collected that characterize, at equilibrium, the heterozygosity, the mean fitness and the fate of populations begun at the allele-frequency centroid. For more than one-half of the trajectories produced by random fertility matrices, there was a decrease in the mean fitness at some time on the way to equilibrium. The mean number of alleles maintained at equilibrium increased only slightly with matrix dimension. Despite the potential for fertility models to display multiple stable equilibria, random fertility models maintain fewer distinct stable points than do random one-locus viability models. Pleiotropic models were also considered with fertility and viability selection operating sequentially within each generation. Most of the equilibrium statistics (with the exception of mean fertility) for the pleiotropic model were intermediate between the corresponding random viability and fertility models.

Alleles↗
PubMed2005

Associates of self-reported fertility status and infertility treatment-seeking in a rural district of Malawi.

BACKGROUND: This study examines the demographic, fertility preference, health/infection and behavioural factors associated with self-reported fertility problems and infertility treatment-seeking in a rural district of Malawi. METHODS: Data come from a population-based survey of 678 women and 362 men. RESULTS: Having a higher ideal number of children than actual number of children, i.e. a 'child deficit', is highly associated with women's reported fertility impairment and treatment-seeking. Other factors associated with women's infertility treatment-seeking are being educated and reporting infertility in self or spouse. In contrast, being in a polygamous union, having exchanged money or goods for sex, and having multiple sex partners are significantly associated with men's reported fertility impairment. Significant factors associated with men's infertility treatment-seeking are having no education, having a long waiting time to pregnancy and having a 'child deficit'. CONCLUSIONS: There is a sex difference in which factors are associated with reported fertility impairment. Fertility preference variables are more often significantly related to women's reported fertility impairment, whereas sexual behaviours are more often significantly related to men's reported fertility impairment.

Adolescent↗
PubMed2005

Investigation of the infertile couple: a basic fertility work-up performed within 12 months of trying to conceive generates costs and complications for no particular benefit.

The current approach of the basic fertility work-up has been questioned recently in this journal. Based on new data on human fecundity, the authors advocated starting the fertility work-up after just 6 months of trying to conceive instead of the usual 12 months. In women younger than 39 years and with a regular cycle, there are several arguments why the basic fertility work-up should not be done earlier than after 12 months of child wish. Firstly, 50% of couples who have tried to conceive for 6 months without success will conceive in the next 6 months without any treatment. Secondly, the prevalence of fertility diseases is lower in couples who have been trying to conceive for 6 months as compared with those who have been trying for 12 months. Performance of a fertility work-up at this stage will lead to an increase in false-positive diagnoses compared with performing them at 12 months of subfertility. Thirdly, fertility treatment will have fewer additional effects in couples with good spontaneous conception prospects (6-12 months child wish), compared with subfertile couples who have poor prospects. At present, none of the available fertility treatments have success rates comparable with no intervention in these women, and postponement of treatment in such couples will prevent complications such as ovarian hyperstimulation syndrome and multiple pregnancies. We argue that the fertility work-up should not be offered to couples with a duration of child wish of <12 months, except for women with ovulation disorders and women of 39 years and older.

Adult↗
PubMed1996

High fertilization prediction by flow cytometric analysis of the CD46 antigen on the inner acrosomal membrane of spermatozoa.

The study was set up to determine the relationship between the human sperm acrosome reaction and fertilization in couples undergoing routine in-vitro fertilization (IVF) treatment. Prospective data analysis was carried out on all IVF patients during a 6 month period. Exceptions were those patients having insufficient sperm concentration to allow both acrosome reaction determination and insemination. The main outcome measures were the prediction of fertilization in IVF patients using flow cytometric analysis of the spontaneous and ionophore-induced acrosome reaction [giving the acrosomal response to ionophore challenge (ARIC) score] in the male partner's spermatozoa versus standard analytical methods of sperm motion parameters and morphology. Stepwise logistic regression indicated only two independent factors predictive of fertilization: ARIC score (chi 2 = 109.6, P < 0.0001) and post-Percoll % motility (chi 2 = 8.8, P < 0.003). Of patients with an ARIC score of > 10, 92% had > 30% of oocytes fertilized; 100% of patients with an ARIC score of < 10 had < 30% fertilization of oocytes. The sensitivity and specificity of the assay system were 1.00 and 0.82 respectively. The results would indicate that the ARIC test as measured by flow cytometric analysis of CD46 binding is a sensitive and specific assay for use in the prediction of fertilization in IVF patients, thus enabling direct channelling of those patients with ARIC scores of < 10 into the more invasive micro-assisted fertilization schemes.

Acrosome↗
PubMed1989

In-vitro processing of sperm with autoantibodies and in-vitro fertilization results.

In-vitro fertilization and embryo transfer were carried out in twenty infertile couples with significant levels of anti-sperm antibodies on the ejaculated spermatozoa. Over 21 cycles (15 couples), 95 mature oocytes were collected and inseminated with spermatozoa obtained by swim-up migration after rapid dilution and washing of the ejaculates. An overall fertilization rate of 38.9% was obtained with these post-migration (PM) preparations. When greater than 70% of the inseminated spermatozoa were covered with both IgG and IgA antibodies, only 14% of the 43 oocytes were fertilized. A higher fertilization rate was obtained with the PM preparations containing less than 70% of spermatozoa coated with one or both classes of antibodies. Under these conditions 60% of the 52 oocytes were fertilized. Fertility rate correlated better with IgG than with IgA antibody levels. In order to decrease the proportion of antibody-coated spermatozoa in the inseminated populations, washed spermatozoa were immuno-adsorbed on Mage's plates before swim-up migration. Over 11 cycles (10 couples) 52 mature oocytes were inseminated with these post-migration immuno-depleted sperm preparations (PMP) containing less than 65% of antibody-coated spermatozoa: 31% of the oocytes were fertilized. This rate compares favourably to IVF results obtained with the PM preparations with greater than 70% of spermatozoa coated with both classes of antibodies. In five couples who had different IVF attempts with the two sperm preparations, the immuno-depletion resulted in a slight increase in the fertilization rates: 10% for the PM preparations versus 26% for the PMP preparations. Sperm binding to the zona pellucida was decreased in the majority of unsuccessful attempts.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Experience with zona drilling and zona cutting to improve fertilization rates of human oocytes in vitro.

Zona drilling (ZD) and zona cutting (ZC) were used in an IVF programme to assist fertilization in semen defect patients. Twenty-seven patients consented to ZD where acidified Tyrode's was used to create a hole in the zona pellucida. In 19 patients, ZD increased the fertilization rate to 29% compared with 8% (P less than 0.001) in their routine IVF cycles, and in eight patients precluded from routine IVF, a fertilization rate of 14% was achieved. Twenty-two patients consented to ZC where a slit in the zona is made mechanically. In 12 patients ZC increased the fertilization rate to 31% compared with 14% (P less than 0.01) from previous routine IVF cycles, and in 10 patients precluded from routine IVF, a fertilization rate of 34% was achieved. In 13 cycles, 68 uncut control oocytes were inseminated. In five cycles both control and ZC oocytes were fertilized (n.s.d.). In eight cycles no control oocytes were fertilized compared with 27% of ZC oocytes. The polyspermy rate was 4.6%. Twenty-four per cent of ZD and 12% of ZC (P less than 0.01) oocytes and embryos were degenerate after 42 h. Both ZD and ZC can increase the fertilization rate of sub-optimal semen, however, in our hands neither technique produced a pregnancy.

Cell Survival↗
PubMed1991

Evaluation of human sperm morphology using strict criteria after Diff-Quik staining: correlation of morphology with fertilization in vitro.

New, very strict criteria were used after Diff-Quik staining for evaluating sperm morphology. The results of morphology scoring were correlated with the fertilization rate in vitro. Semen samples from 64 men participating in an in-vitro fertilization programme were used for this study. All men had to have a sperm concentration of greater than or equal to 20 million/ml and a progressive motility of greater than 30%. The morphology evaluation using strict criteria was performed on the same aliquot of semen as that used for in-vitro insemination. If strict criteria showed that normal morphology was less than or equal to 4%, the fertilization rate per oocyte was 23%. If normal morphology was greater than or equal to 11%, 77% fertilization occurred. For proportions of normal morphology between 4 and 11%, the fertilization rate per oocyte was 59% (P less than 0.000001). Among all these morphology groups, classical semen parameters, such as the mean volume, the mean concentration and the mean motility, did not differ significantly, except for the morphology evaluation using WHO criteria. The correlation with fertilization was better for morphology evaluation using strict criteria than for WHO. In conclusion, the method of evaluating sperm morphology based on very strict criteria allows a more accurate prediction of the chance of fertilization in vitro. Further studies should be done to establish the most appropriate cut-off points for severely impaired, intermediate and high fertilization rates.

Azure Stains↗
PubMed1992

Interdependent influence of follicular fluid oestradiol concentration and motility characteristics of spermatozoa on in-vitro fertilization results.

Methods are presented for an objective assessment of the quality of both gametes in an in-vitro fertilization programme. The concentrations of oestradiol and progesterone in follicles whose oocytes did or did not fertilize, were measured and assessed as potential markers of oocyte maturity. There was no difference in the mean concentrations of either steroid in follicular fluid of fertilized and unfertilized oocytes. However, a highly significant inverse correlation was observed between the oestradiol concentration in follicles of oocytes becoming fertilized and the number of spermatozoa added for fertilization (P less than 0.001). Follicular fluid concentrations of progesterone did not correlate with the number of inseminated spermatozoa. The correlation between follicular oestradiol concentrations and the number of spermatozoa needed for fertilization was then used to identify movement characteristics of spermatozoa in the culture medium which were relevant for fertilization. Sufficient numbers of spermatozoa having specific values of head cross frequency, lateral head displacement, linearity and curvilinear velocity were critical for the occurrence of fertilization in vitro.

Adult↗
PubMed1992

The use of cryopreserved aged human oocytes in a test of the fertilizing capacity of human spermatozoa.

The use of cryopreserved aged human oocytes in a diagnostic test of sperm fertilizing ability was evaluated. Oocytes arising from assisted conception cycles and showing no signs of fertilization 48 h post-insemination were cryopreserved by one of two methods. An ultrarapid method using dimethyl sulphoxide gave poor post-thaw results, with only 5/69 (7.2%) oocytes surviving. Oocytes frozen by a slow method using propanediol as the cryoprotectant gave better survival rates (359/594; 60%). Fertilization by donor spermatozoa of these thawed oocytes was poor (15/63; 24%) when the zona pellucida was left intact. To improve this, the zona was enzymatically removed using pronase. These zona-free oocytes were then inseminated with spermatozoa from a fertile donor or from men previously exhibiting fertilization failure in an in-vitro fertilization treatment cycle. The fertilization rate in the patient group (41/91; 45%) was significantly lower than in the donor group (16/18; 89%) (P less than 0.02). There was also a significant (P less than 0.03) reduction in the median number of pronuclei per oocyte (2.9 versus 4.5). These results show that aged oocytes can be effectively cryopreserved to establish a bank for use in a test to identify men with impaired sperm fertilizing capacity.

Cell Survival↗
PubMed1992

An evaluation of couples with failure of fertilization in vitro.

Attempts at in-vitro fertilization (IVF) may be used as a method of evaluating whether in a given couple, the inability of the sperm to fertilize the oocyte may be the cause of infertility. We evaluated all IVF patients in our practice who had at least one cycle with no fertilization to determine how often this was an isolated event or was repeated in multiple cycles; would poor semen quality be found as a frequent cause; and how well can a donor sperm or oocyte 'probe' uncover which of the two is the problem? Of 35 couples who used their own gametes exclusively, 30 (85.7%) had at least one cycle with zero fertilization; 42.5% of those failing to fertilize in cycle 1 and 35% of those failing in cycle 2 had a subnormal concentration of motile spermatozoa, morphology or hypo-osmotic swelling test scores. The pregnancy rate per cycle with both husband's and wife's gametes was only 2.3% (3/130), but was 8.3% for those using donor spermatozoa (3/36) and 18.2% (2/11) for donor oocytes. Thus, failing to fertilize in a given cycle does not necessarily predict failure to fertilize in a subsequent cycle, but does predict a poor fertility outcome unless donor gametes are used.

Adult↗
PubMed1994

Micro-assisted fertilization in patients who have failed subzonal insemination.

During the past 3 years we have used direct injection of spermatozoa into the cytoplasm of the oocyte (DISCO) in an attempt to procure conception in vitro where subzonal insemination (SUZI) has failed. Acknowledging the paucity of information about this invasive procedure in humans, it was clearly the only alternative for some patients. A total of 58 patients (cycles) who had had previously failed SUZI elected for this approach. Sibling oocytes, where possible, were used as a comparison between DISCO, SUZI, partial zona dissection (PZD) and microdrop in-vitro fertilization (IVF). Fertilization and embryo transfer was achieved by 66% (n = 38) of patients. Patients with embryos derived solely from DISCO (n = 19) produced four clinical pregnancies (21%), four patients had embryo transfer from SUZI embryos only with no pregnancies, and 15 had embryo transfer from a mixture of SUZI and DISCO embryos, with one dizygotic twin pregnancy from a combined SUZI and DISCO embryo transfer (7%). Twins, one male and one female, have been delivered, there has been one miscarriage and two pregnancies are ongoing. Of the 627 oocytes, 251 were used for DISCO and 71 (28%) were fertilized, 296 were used for SUZI and 29 (10%) were fertilized; 70 were used for PZD, two (3%) were fertilized, and none of the 10 undergoing microdrop IVF were fertilized. Of the 58 patients (cycles) 31% (n = 19) had fertilization with DISCO only, 8% (n = 4) with SUZI only, 28% (n = 15) with both SUZI and DISCO, while only one (2%) had fertilization with PZD.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2002

Fertility of broiler breeders following categorization by the OptiBreed sperm quality index when hens are inseminated with a constant number of sperm.

If semen quality was known prior to insemination, sperm doses could possibly be decreased, maximizing the number of hens inseminated. The sperm quality index (SQI), an indicator of overall semen quality, is determined by the number of deflections in a light path due to sperm movement inside a capillary tube. The objectives of this study were 1) to determine the age at which the SQI becomes a static predictor of semen quality and 2) to determine if fertility of males with a higher SQI responds more favorably to insemination dose reduction than that of males with a lower SQI. Weekly from 23 to 32 wk of age, 144 Cobb males were tested for SQI. At 32 wk of age, males were placed into four groups that represented the SQI population quartiles as follows: poor, fair, good, and best. A fifth SQI group, uncategorized, was created to determine fertility of the original population by mixing equal amounts of semen from each of the four groups. Semen was collected weekly from 33 to 40 wk of age from 18 males in each of the four groups, pooled by group, and used to inseminate 30 hens per group with 50 or 100 million sperm. Eggs were collected daily, incubated, and broken out to determine fertility. Correlation coefficients between weekly SQI results and overall averages for individual males indicated that the SQI stabilized after the birds were 28 wk of age. The main effect for SQI selection revealed that the best SQI group had the highest fertility (88%), which did not differ from the good (83%) or fair group (82%) but was greater than the uncategorized group (80%). Fertilities of the top three groups and the uncategorized group were higher than the poor group (63%) (P < 0.0001, SEM 2.18). In addition, there was an interaction between SQI classification and insemination dose. Fertilities of the top three SQI groups were similar at the 50 and 100 million sperm doses. However, the poor and uncategorized SQI groups had lower fertility at the 50 million dose as compared to the 100 million dose. By categorizing males into SQI groups after 28 wk of age, insemination dose can be reduced, maximizing a male's fertilizing potential.

Animals↗
PubMed2003

Semen dilution prior to analysis influences the ability of the sperm quality analyzer to predict fertility whether inseminating with a constant number of sperm or a constant volume of semen.

Previous research has shown that the sperm quality index (SQI) is positively correlated with semen characteristics as well as fertility when broiler breeder semen is diluted 10-fold prior to analysis. However, research has not been conducted to establish if semen dilution rate affects the ability of the SQI to predict fertility when inseminating a constant number of sperm or a constant volume of semen. As a result, 3 experiments were undertaken. The objective of the first study was to determine if diluent, minimum essential media, or 0.85% saline affects the SQI. The second objective was to identify potential semen dilution rates for the SQI by obtaining the range in live sperm concentrations to which the SQI is most sensitive. The purpose of experiment 3 was to determine which semen dilution rate, 10-, 25-, 50-, 75-fold, or a constant concentration of 180 x 10(6) sperm/mL, yields an SQI that is most predictive of fertility. Once a week for 3 wk, 20 hens were individually inseminated with either 20 microL of 4-fold diluted semen or a constant 45 x 10(6) sperm from each of 29 broiler breeder males. To determine which semen dilution rate yielded an SQI that was most predictive of fertility, Pearson's correlation coefficients were obtained between the SQI at each dilution rate and fertility. There was no difference in the SQI due to diluent. Sperm quality index values declined logarithmically as live sperm concentration decreased. The SQI was most sensitive to live sperm concentrations from 11 to 232 x 10(6) sperm/mL. The SQI for semen diluted 10-fold was the best predictor of fertility when inseminating with a constant volume of 4-fold diluted semen (r = 0.71). When hens were inseminated with a constant 45 x 10(6) sperm/hen, the SQI for semen diluted 10- and 25-fold as well as to a constant concentration of 180 x 10(6) sperm/ mL was equally effective at predicting fertility (r = 0.59, 0.52, and 0.61, respectively). Apparently, the SQI is predictive of fertility when semen samples are diluted 10-fold prior to analysis regardless of insemination method used. Dilution beyond 10-fold appears to alter semen quality, rendering the SQI less accurate.

Animals↗
PubMed2003

Potential relationships between physical traits and male broiler breeder fertility.

Genetic selection in primary broiler breeders may modify skeletal structure, possibly impeding semen transfer, and could alter the size and degree of fluctuating asymmetry (FA) of bilateral traits associated with fertility. Hence, we hypothesized specific morphometric traits could predict differential fertility. Sixty primary broiler breeder males from Strains A and B (n = 30/strain) were individually housed with an average of 10 females per male. Male fertility and sperm penetration (SP) through the perivitelline layer were estimated on fresh eggs. At 50 wk, BW, keel length (KL), posterior pelvic width and length (PPW, PPL), dorsal pelvic width and length (DPW, DPL), tarsometatarsal length and width (TL, TW), comb length and width (CL, CW), and wattle length, width, and area (WL, WW, WA) were measured. Results indicated that Strain A had smaller BW, KL, WL, WW, WA, CL, CW, PPL, DPL, and DPW. A higher degree of FA was found in Strain A TL and WL (P < 0.05), yet DPW FA was greater for Strain B (P < 0.001). In addition, DPW FA negatively correlated with Strain B fertility (r = -0.369; P < 0.01); however, other FA measurements did not correlate with estimated fertility or SP. Strain A WL correlated with SP (r = 0.383; P < 0.01) and fertility (r = 0.346; P < 0.01). Results indicate DPW alteration may impact semen transfer upon copulation, as Strain A fertility negatively correlated with DPW (r = -0.298; P < 0.05). This research provides evidence that morphometric traits might be useful to predict fertility in broiler breeders.

Animals↗
PubMed2003

Fertilization and development of quail oocytes after intracytoplasmic sperm injection.

The present study was conducted to establish the intracytoplasmic sperm injection (ICSI) method for in vitro fertilization and development in quail. The efficiency of fertilization of oocytes was compared 1) between spontaneous and premature ovulation and 2) among testicular round spermatids, elongated spermatids, and immature and mature spermatozoa. The oocytes were injected with a single spermatozoon or spermatid and cultured for 24 h. Cell division was histologically observed with hematoxylin-eosin (HE) and a nucleus-specific fluorescent dye (DAPI). Five of 30 (16.6%) and 4 of 30 (13.3%) oocytes injected with mature sperm were fertilized in the spontaneous and induced ovulation group, respectively. Those embryos showed development at stages II-VII. Half the number (three of six) of the oocytes injected with testicular spermatozoa were fertilized and developed to stages IV-VII, and two of five oocytes injected with elongated spermatids were fertilized and developed to stage VI. All ooocytes injected with round spermatids were unfertilized. The results demonstrate that intracytoplasmic injection of a single sperm into quail oocyte can activate the oocyte and lead to fertilization. Oocytes prematurely ovulated are capable of fertilizing with mature sperm as are those spontaneously ovulated. In addition, the results suggest that the testicular round spermatids may not possess sufficient oocyte-activating potency but that the elongated spermatids and immature spermatozoa are competent to participate in fertilization and early embryonic development in quail.

Animals↗
PubMed2004

Requirements for glucose beyond sperm capacitation during in vitro fertilization in the mouse.

In both the mouse and the human, it is a point of controversy whether glucose is necessary for in vitro fertilization. Some of this controversy has resulted from a failure to distinguish between requirements for glucose during sperm capacitation versus requirements during the multistage process of fertilization. Using the mouse as a model, we performed a series of experiments designed to identify specific processes that might require glucose. We observed a positive correlation between increasing glucose concentrations during capacitation and fertilization, and increasing fertilization of zona pellucida (ZP)-intact eggs. These data supported a requirement for glucose in the fertilization medium even when sperm were first capacitated in the presence of 5.5 mM glucose. This glucose requirement was observed for both ZP-intact and ZP-free eggs. During ZP-free in vitro fertilization, some binding and fusion between the plasma membrane of the sperm and egg occurred in the absence of glucose and at concentrations less than 1 mM, suggesting that this substrate is not absolutely required. However, glucose concentrations of 1 mM or higher greatly facilitated both binding and fusion under these conditions. These subtle distinctions suggest that during ZP-free in vitro fertilization, 1 mM glucose represents a threshold level that facilitates binding and fusion. Taken as a whole, the data suggest requirements for glucose during both capacitation and fertilization under normal physiologic conditions.

Animals↗