Population Fertility Research Articles

Characterization of cystic fibrosis conductance transmembrane regulator gene mutations and IVS8 poly(T) variants in Portuguese patients with congenital absence of the vas deferens.

Cystic fibrosis conductance transmembrane regulator (CFTR) gene mutations and IVS8 poly(T) variants in Portuguese patients with bilateral (CBAVD) and unilateral (CUAVD) congenital absence of the vas deferens remain to be evaluated. Patient screening was carried out by PCR, denaturing gradient gel electrophoresis and DNA sequencing. CFTR mutations were found in 18 out of 31 (58.1%) CBAVD and in three of four (75%) CUAVD patients. The most frequent mutations were F508del and R334W in CBAVD and G542X in CUAVD, with the allelic frequencies of R334W (6.5%) and G542X (25%) being particular to the Portuguese population. The 5T allelic frequency was 3.5% in the fertile male population, 25% in CUAVD and 27.4% in CBAVD patients. The combined frequency of mutations (CFTR+5T) was increased in CBAVD to 22 out of 31 (71%). The frequency of CFTR mutations was compared with that of patients with secondary obstructive azoospermia (OAZ; one out of 16, 6.3%) and non-obstructive azoospermia (NOAZ; two out of 22, 9.1%) with conserved spermatogenesis, which were similar to the general population. However, whereas the 5T allelic frequency in OAZ was similar to that of the general population (3.1%), it was increased in NOAZ cases (14.3%). Data confirm that CFTR+5T mutations represent the most common genetic abnormality in CAVD, and suggest that cases of NOAZ may be associated with the 5T allele.

The Demographic Transition and the Emergence of Sustained Economic Growth

The demographic transition that swept the world in the course of the last century has been identified as one of the prime forces in the transition from stagnation to growth. The unprecedented increase in population growth during the early stages of industrialization was ultimately reversed and the demographic transition brought about a significant reduction in fertility rates and population growth in various regions of the world, enabling economies to convert a larger share of the fruits of factor accumulation and technological progress into growth of income per capita. This paper examines various mechanisms that have been proposed as possible triggers for the demographic transition, assessing their empirical validity, and their potential role in the transition from stagnation to growth. (JEL: O11, O14, O33, O40, J11, J13)

Does intracytoplasmic sperm injection (ICSI) carry inherent genetic risks?

The use of ICSI provides an effective treatment for severe male factor infertility (1). If viable sperm are available, the pregnancy rates are unaffected by the semen characteristics and sperm quality because the technique bypasses the zona pellucida and oolemma to deliver the male genome directly into the ooplasm. This allows couples with compromised semen parameters to achieve pregnancy rates comparable to those achieved with IVF with conventional fertilization. ICSI now can be performed in azoospermic men if spermatozoa can be collected from the epididymis or the testis (2–4). Because the spermatozoon used for fertilization is selected by the operator, and not by natural selection in the reproductive tract, the zona pellucida, and oolemma, concerns regarding safety have been raised. Some reports have suggested a possible increased risk of sex chromosomal abnormalities in ICSI pregnancies (5). ICSI is compatible with normal development (6, 7), and it is no longer regarded as an experimental procedure (8). ICSI may be associated with a higher incidence of congenital defects (9), and children conceived with ICSI have been reported to achieve a significantly lower performance on the Bayley Scale of Infant Development at one year of age (10). A larger study concluded that children conceived with ICSI did not perform differently at two years of age than those conceived following conventional IVF, and both groups performed better than the fertile control population (11, 12).

Alvin Hansen on Economic Progress and Declining Population Growth

Alvin Hansen on Economic Progress and Declining Population Growth

Birth seasonality in the Old Order Amish.

The Old Order Amish are a healthy and well-nourished natural fertility population, so that the timing of births is not influenced by behaviours to limit family size, undernutrition or disease. The present study examines the monthly distribution of 8160 births occurring between 1920 and 1991 in the Geauga Settlement in north-east Ohio, USA. The monthly distribution of births in the Geauga Settlement is bimodal, with a major peak extending from August to October, a minor peak in February, and a major trough from April to June. This pattern is almost identical to the pattern found in the US in 1943. The monthly distribution of first births appears to be influenced to some extent by a highly significant seasonal pattern of weddings. The pattern of births in the Old Order Amish is consistent with the hypothesis that the spring trough in US births is at least partially caused by a decrease in coital frequency and/or a decrease in fecundability as a result of hot summer temperatures but is not consistent with the hypothesis that the fall peak in US births is primarily due to an increase in coital frequency during the Thanksgiving and Christmas holiday seasons.

Significance of endometrial polyps detected hysteroscopically in eumenorrheic infertile women.

To determine if the incidence of small endometrial polyps detected hysteroscopically in an infertile eumenorrheic population differed from that in an apparently fertile eumenorrheic population. Evidence was sought to determine whether removal of such lesions would enhance reproductive performance. In a prospective study, 266 consecutive infertile women had undergone complete fertility evaluation. None of the women had experienced any change in their menstrual cycle. They were divided into two groups; 235 infertile patients (group 1) and 31 requesting a reversal of a previous tubal sterilization (group 2). All patients were examined by simultaneous combined laparoscopy and hysteroscopy as part of their routine infertility evaluation. When endometrial polyps were noted they were removed by hysteroscopy and histopathologically examined. Patients in whom the only apparent finding was endometrial polyps were followed up to determine their reproductive outcomes subsequent to removal of the polyps. Of the 224 uterine cavities successfully visualized in the infertile group, 134 were judged to be normal (60%) and 90 were abnormal (40%). Endometrial polyps were noted in 35 patients of group 1 and in one patient of group 2 (P < 0.01). Most polyps were located in the region of the utero-tubal junction and proved to be functional. A 50% pregnancy rate was achieved by hysteroscopic polypectomy. Fertility-related factors in women whose only apparent finding was endometrial polyps before and after hysteroscopy were comparable. Diagnostic hysteroscopy should be used routinely in the work-up of infertile woman, even in the presence of eumenorrhea. Persistent functional endometrial polyps, even if small, are likely to impair fertility in this select patient group. Removal of such lesions may improve subsequent reproductive performance.

An evolutionary model of stature, age at first birth and reproductive success in Gambian women.

We have built a model to predict optimal age at first birth for women in a natural fertility population. The only existing fully evolutionary model, based on Ache hunter-gatherers, argues that as women gain weight, their fertility (rate of giving birth) increases-thus age at first birth represents a trade-off between time allocated to weight gain and greater fertility when mature. We identify the life-history implications of female age at first birth in a Gambian population, using uniquely detailed longitudinal data collected from 1950 to date. We use height rather than weight as an indicator of growth as it is more strongly correlated with age at first birth. Stature does not greatly influence fertility in this population but has a significant effect on offspring mortality. We model age at first reproduction as a trade-off between the time spent growing and reduced infant mortality after maturation. Parameters derived from this population are fitted to show that the predicted optimal mean age of first birth, which maximizes reproductive success, is 18 years, very close to that observed. The reaction norm associated with variation in growth rate during childhood also satisfactorily predicts the variation in age at first birth.

The Biocultural Context of Very High Fertility among the Bekaa Bedouin

This research report explores some of the biocultural dimensions of maximum or near maximum fertility among Bedouin tribes in the Bekaa Valley, Lebanon. The Bedouin case substantiates that very high fertility (completed family size [CFS] greater than 8.0) is found among peripheral peoples in frontier situations generated by major political-economic shifts. While the Bedouin maintained high fertility (CFS > 6.5) for approximately sixty years (1899–1960), very high fertility—linked to greater historical reliance on agriculture—was of shorter duration (1934–60). Comparisons with other very high fertility populations indicate that, at the proximate level, maximum fertility is associated with early weaning, low rates of primary sterility, and high rates of marital stability. Results also point to low subadult mortality in Bedouin society. Low mortality is best attributed to the availability of modern medical care facilities and high-quality weaning foods.

Monitoring Leaf Nitrogen Status in Rice with Canopy Spectral Reflectance

Nondestructive monitoring and diagnosis of plant N status is necessary for precision N management. The present study was conducted to determine if canopy reflectance could be used to evaluate leaf N status in rice (Oryza sativa L.). Ground‐based canopy spectral reflectance and N concentration and accumulation in leaves were measured over the entire rice growing season under various treatments of N fertilization, irrigation, and plant population. Analyses were made on the relationships of seasonal canopy spectral reflectance, ratio indices, and normalized difference indices to leaf N concentration and N accumulation in rice under different N treatments. The results showed that at each sampling date, leaf N concentration was negatively related to the reflectance at the green band (560 nm) while positively related to ratio index, with the best correlation at jointing. However, the relationships between leaf N accumulation and reflectance at green band and ratio index were consistent across the whole growth period. The ratio of near infrared (NIR) to green (R810/R560) was especially linearly related to total leaf N accumulation, independent of N level and growth stage. Tests of the linear regression model with different field experiment data sets involving different plant densities, N fertilization, and irrigation treatments exhibited good agreement between the predicted and observed values, with an estimation accuracy of 96.69%, root mean square error of 0.7072, and relative error of −0.0052. These results indicate that the ratio index of NIR to green (R810/R560) should be useful for nondestructive monitoring of N status in rice plants.

EFFECTS OF ESTRADIOL ON COGNITION EVALUATED WITH P300 IN IN VITRO FERTILIZATION PATIENTS

The authors planned to show the effect of high-level estrogen on cognitive functions, using P300 in the in-vitro fertilization (IVF) population. Eighteen IVF patients (mean age 31.39 ± 5.01) without any detectable cognitive disorder were enrolled in this study. The authors measured N100, P200, N200, P300 latencies and amplitudes at Cz and Fz recordings during the lowest and highest blood estradiol levels. P300 amplitudes were significantly reduced during the highest level of estradiol compared to the lowest level both at Fz and Cz recordings. The other subcomponents of P300 were not significantly influenced by blood estradiol levels. The results revealed a decline in the ability of task relevance and state of arousal when the estradiol level was the highest in the IVF patients.

Embarazo ectópico tubárico tras programa FIV embarazo ectópico abdominal

The treatment of ectopic pregnancy depends on early diagnosis, made conjointly by diagnostic methods such as determination of levels of ®-HGC, transvaginal sonography and culdocentesis prior to surgical intervention: laparoscopy or laparotomy or expectant medical management.Ectopic pregnancy has an incidence of 0.94% to 2.6% of gestations. Between 4% and 8% of ectopic pregnancy is encountered following ovarian stimulation and in the assisted reproduction programme IVF its incidence is between 2.1% and 9.4%, a very high frequency in comparison to the general fertile population. The prognosis of these patients is that ectopic pregnancy is responsible for 2% to 5% of maternal deaths due to complications such as haemorrhagic shock.

Ineffective Contraceptive Use and Its Causes in a Natural Fertility Population in Southern Jordan

Based on our interview survey of 574 randomly selected married women from a rural population in the South Ghor district, Jordan, where traditional Arab customs have been persistently maintained, in this paper we analyze the age-specific marital fertility rates (ASMFRs) and contraceptive practices, especially the prevalence and duration of contraceptive use. The ASMFRs fitted the natural fertility pattern proposed by Coale and Trussell's model, and the total fertility rate was estimated to be 7.2. Even though the prevalence rate of modern contraceptive methods has reached 14.3%, because of the recent increase among young women in particular, the users had larger numbers of children than the nonusers and the duration of contraceptive use was short, especially at young ages (e.g., about 90% 24-month discontinuation probabilities in 15-19- and 20-24-year-olds). These ineffective contraceptive uses were related to traditional Arab norms, represented by the pooled proportion of "as many as possible" and "up to God" answers to the ideal number of children (70% of men and 30% of women).

Using Zero-inflated Count Regression Models To Estimate The Fertility Of U. S. Women

In the modeling of count variables there is sometimes a preponderance of zero counts. This article concerns the estimation of Poisson regression models (PRM) and negative binomial regression models (NBRM) to predict the average number of children ever born (CEB) to women in the U.S. The PRM and NBRM will often under-predict zeros because they do not consider zero counts of women who are not trying to have children. The fertility of U.S. white and Mexican-origin women show that zero-inflated Poisson (ZIP) and zero-inflated negative binomial (ZINB) models perform better in many respects than the Poisson and negative binomial models. Zero-inflated Poisson and negative binomial regression models are statistically appropriate for the modeling of fertility in low fertility populations, especially when there is a preponderance of women in the society with no children.

Does caffeine intake impair semen quality and hormonal levels in a fertile population?

Objective: The goal of this study was to assess number of cups (100 ml) of coffee intake per day and correlate with semen quality and hormonal levels in men undergoing vasectomy for sterilization purposes.Design: Retrospective study.Material and Methods: From January 1999 to September 2002, 750 vasectomies for voluntary sterilization purposes were performed. We divided our patients into four groups: does not drink coffee (n = 232), mild drinkers (1–3 cups/day; n = 156), moderate drinkers (4–6 cups/day; n = 198), and heavy drinkers (> 6 cups/day; n = 164). A manual hand count and Computer-assisted semen analysis was performed on all specimens, with a Motion Analysis VP 50 semen analyzer. In addition, hormonal levels were assessed. We evaluated sperm concentration, motility, motion parameters, and hormonal levels in these men. Data was evaluated with ANOVA.Results: No differences were seen in sperm concentration (p = 0.293), motility (0.06), follicle-stimulating hormone (p = 0.962), luteinizing hormone (p = 0.138), and serum total testosterone (p = 0.313). However, sperm motility was higher in patients who drink coffee compared to patients who does not drink coffee (p = 0.04). Sperm motion characteristics did not differed across the groups: linear velocity (p = 0.095), linearity (p = 0.142), lateral head displacement (p = 0.616), beat cross frequency (p = 0.115), and curvilinear velocity (p = 0.675).Conclusions: No significant differences were detected in sperm concentration, motility, sperm motion characteristics and hormonal levels in mild, moderate, heavy and non-smokers fertile patients. However, sperm motility was higher in patients who drink coffee compared to patients who does not drink coffee. Therefore, the use of compounds with an active principle based on caffeine may be stimulated for patients with astenozoospermia. Objective: The goal of this study was to assess number of cups (100 ml) of coffee intake per day and correlate with semen quality and hormonal levels in men undergoing vasectomy for sterilization purposes. Design: Retrospective study. Material and Methods: From January 1999 to September 2002, 750 vasectomies for voluntary sterilization purposes were performed. We divided our patients into four groups: does not drink coffee (n = 232), mild drinkers (1–3 cups/day; n = 156), moderate drinkers (4–6 cups/day; n = 198), and heavy drinkers (> 6 cups/day; n = 164). A manual hand count and Computer-assisted semen analysis was performed on all specimens, with a Motion Analysis VP 50 semen analyzer. In addition, hormonal levels were assessed. We evaluated sperm concentration, motility, motion parameters, and hormonal levels in these men. Data was evaluated with ANOVA. Results: No differences were seen in sperm concentration (p = 0.293), motility (0.06), follicle-stimulating hormone (p = 0.962), luteinizing hormone (p = 0.138), and serum total testosterone (p = 0.313). However, sperm motility was higher in patients who drink coffee compared to patients who does not drink coffee (p = 0.04). Sperm motion characteristics did not differed across the groups: linear velocity (p = 0.095), linearity (p = 0.142), lateral head displacement (p = 0.616), beat cross frequency (p = 0.115), and curvilinear velocity (p = 0.675). Conclusions: No significant differences were detected in sperm concentration, motility, sperm motion characteristics and hormonal levels in mild, moderate, heavy and non-smokers fertile patients. However, sperm motility was higher in patients who drink coffee compared to patients who does not drink coffee. Therefore, the use of compounds with an active principle based on caffeine may be stimulated for patients with astenozoospermia.

Patterns of prey capture and prey availability among populations of the carnivorous plant Pinguicula moranensis (Lentibulariaceae) along an environmental gradient

In this study we explored the effect of the physical environment and the availability of prey (biomass and taxonomic composition) on the patterns of prey capture and reproduction on five populations of Pinguicula moranensis (Lentibulariaceae) in areas ranging from pine-oak forests to desert scrublands. Environmental variation was summarized using principal factor analysis. Prey availability and prey capture increased toward the shadiest, most humid, and fertile population. The probability of reproduction and average bud production per population did not follow the same tendency because both fitness components peaked at the middle of the environmental gradient. These results suggest that the benefits derived from carnivory are maximized at sites fulfilling a trade-off between light, moisture, and prey availability. We also found that the taxonomic composition of both the available prey and that of the prey captured by plants varied among populations. The results also indicated that the prey captured by plants are not a random sample of prey available within populations. Overall, the results from this study revealed a marked amount of heterogeneity in the physical and biotic environment among the populations of P. moranensis, which has the potential to affect the outcome of the interaction between this carnivorous species and its prey.

Gibberella konza (Fusarium konzum) sp. nov. from prairie grasses, a new species in the Gibberella fujikuroi species complex

The Gibberella fujikuroi species complex (Fusarium section Liseola and allied taxa) is composed of an increasingly large number of morphological, biological and phylogenetic species. Most of the known species in this group have been isolated from agricultural ecosystems or have been described from a small number of isolates. We sampled Fusarium communities from native prairie grasses in Kansas and recovered a large number of isolates that superficially resemble F. anthophilum. We used a combination of morphological, biological and molecular characters to describe a new species, Gibberella konza (Gibberella fujikuroi mating population I [MP-I]), from native prairie grasses in Kansas. Although female fertility for field isolates of this species appears to be low, G. konza is heterothallic, and we developed reliably female fertile mating population tester strains for this species. The F. konzum anamorph is differentiated from F. anthophilum and from other Fusarium species in section Liseola by mating compatibility, morphology, AFLP fingerprint profile and differences in β-tubulin DNA sequence.

Gibberella konza (Fusarium konzum) sp. nov. from Prairie Grasses, a New Species in the Gibberella fujikuroi Species Complex

The Gibberella fujikuroi species complex (Fusarium section Liseola and allied taxa) is composed of an increasingly large number of morphological, biological and phylogenetic species. Most of the known species in this group have been isolated from agricultural ecosystems or have been described from a small number of isolates. We sampled Fusarium communities from native prairie grasses in Kansas and recovered a large number of isolates that superficially resemble F. anthophilum. We used a combination of morphological, biological and molecular characters to describe a new species, Gibberella konza (Gibberella fujikuroi mating population I [MP-I]), from native prairie grasses in Kansas. Although female fertility for field isolates of this species appears to be low, G. konza is heterothallic, and we developed reliably female fertile mating population tester strains for this species. The F. konzum anamorph is differentiated from F. anthophilum and from other Fusarium species in section Liseola by mating compatibility, morphology, AFLP fingerprint profile and differences in β-tubulin DNA sequence.

Genes and male infertility: what can go wrong?

Genes and male infertility: what can go wrong?

Optimal Plant Population and Nitrogen Fertility for Dryland Corn in Western Nebraska

Dryland corn (Zea mays L.) production increased more than 10‐fold from 1995 through 2000 in semiarid western Nebraska. Corn population and N fertilizer management recommendations are needed for this area. The objectives of this study were to determine the influence of plant population and N fertility on corn yields in semiarid western Nebraska. In 1999 and 2000, experiments were conducted each year at four sites. Factorial experimental treatments were five plant populations (17300, 27200, 37100, 46900, and 56800 plants ha−1) and five N fertilizer rates (0, 34, 67, 101, and 134 kg N ha−1) arranged in a randomized complete block with five blocks. Corn yields ranged from less than 100 kg ha−1 to more than 5550 kg ha−1. Overall, grain yield increased 353 kg ha−1 with increasing population from 17300 to 27200 plants ha−1. Population increases above 27200 plants ha−1 resulted in inconsistent yield results. Nitrogen fertilization and plant population effects did not interact. Yields were maximized by 202 kg N ha−1 in the form of soil NO3–N and fertilizer N available before crop emergence. Growers are advised to use a plant population of 27200 plants ha−1. Economic optimal fertilizer rate can be estimated using the equation: Nfert. = (10.6 × Pcorn − Pfert.)/(0.0526 × Pcorn) − Nsoil, where Pcorn and Pfert. are corn and fertilizer price ($ kg−1), respectively, Nsoil is soil test NO3–N (kg ha−1) as determined by preplant soil test in a 0‐ to 120‐cm soil sample, and Nfert. is economic optimal fertilizer rate (kg ha−1).

Changing Human Populations in Post-Soviet Kamchatka: An Integrated Study of Shifts in Fertility and Net Population

We expect population changes to be closely tied to resource abundance or scarcity. Here, I demonstrate a clear relationship between the widespread socio-economic crisis of the post-Soviet period and declining population patterns in central Kamchatka. These broad patterns, however, vary among populations, reflecting particular interlinked socio-economic, ecological, and historical conditions. More dramatic decline is observed in areas where the socio-economic crisis has coincided with a local natural resource crisis. Analyzing population shifts in the context of local circumstances, this paper corroborates the link between resource conditions and changes at the family level.