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PubMed1995

Immunity in humans to Necator americanus: IgE, parasite weight and fecundity.

The effect of the humoral immune response on the weight and fecundity of the hookworm Necator americanus was examined in an endemically-infected human population. There was a highly significant negative correlation between total IgE levels and parasite weight and fecundity, after controlling for any effects of host age and hookworm burden. This correlation was present both at initial treatment and after 2 years' reinfection. There was a similar negative correlation between the number of eosinophils and hookworm weight and fecundity at initial treatment. Correlations with levels of specific antibodies to N. americanus excretory-secretory products were weaker and not significant, although there was a trend towards negative correlations with anti-ES IgE. This is the first field evidence for an effective human immune response to N. americanus. Although the mechanism of this effect is not clear, we suggest that total IgE levels reflected the level of Th2 cell activation.

Animals↗
PubMed2006

Population size, female fecundity, and sex ratio variation in gynodioecious Plantago maritima.

Theory predicts that the sex ratio of gynodioecious populations (in which hermaphrodites and females coexist) will be affected by the relative female fitness of females and hermaphrodites, and by founder events and genetic drift in small populations. We documented the sex ratio and size of 104 populations of the gynodioecious, perennial herb Plantago maritima in four archipelagos in eastern Sweden and western Finland (from latitude 53 to 64 degrees N). The sex ratio varied significantly both among and within archipelagos (range 0-70% females, median 6.3% females). The frequency of females was highest in the northernmost archipelago and lowest in the southernmost archipelago. As predicted, females were more frequently missing from small than from large populations, and the variance in sex ratio increased with decreasing population size. The relative fecundity of female plants (mean seed output per female/mean seed output per hermaphrodite) ranged from 0.43 to 2.16 (median 1.01, n = 12 populations). Among the 12 populations sampled for seed production (four in each of three archipelagos), the frequency of females was positively related to relative fecundity of females and negatively related to population size. The results suggest that the local sex ratio is influenced both by the relative fecundity of females and hermaphrodites and by stochastic processes in small populations.

Environment↗
PubMedDate not supplied

The sperm penetration test (P-test) can predict fecundability in the male partner from infertile couples.

Three hundred and twenty-one consecutive couples were investigated for infertility at Hvidovre University Hospital in the period from November 1977 to June 1985. The male partners were evaluated in two ways: the classical semen analysis, and the ability of sperm to penetrate fresh hen egg white, the P-test. A Cox regression analysis was used to describe the relation between these variables and fecundability, i.e. the time required to conceive. Four of thirteen variables--the number of morphologically normal spermatozoa, the number of motile spermatozoa, the P-test, and the man's age--each have significant relation to the fecundability. However, when covariation is considered, only the P-test and the man's age possess significant prognostic information, whereas the variables of the classical semen analysis do not. This indicates that the P-test may replace the classical semen analysis when trying to predict individual pregnancy probabilities. Finally, the P-test and the man's age are combined to form a prognostic index which predicts the fecundability of the male partner in the individual infertile couple.

Adult↗
PubMed1994

Behavioral and biological determinants of fecundability.

Our discussion has focused on a set of behavioral and physiological factors which influence fecundability. Some potentially important determinants are notable primarily because of their absence. Foremost among these determinants (as a group) are the male attributes. We have, by and large, ignored the links between male sexual behavior and hormonal profiles and the effects of hormones (or other factors) on sperm function. The fact that we have not reviewed them here does not imply that we believe that they are unimportant. Indeed, the effects of male factors may be particularly important because in some settings men are the predominant, if not the sole, decision-makers regarding reproductive behaviors including initiation of sexual intercourse and use of contraception. Also conspicuous by their absence are the effects of nutrition, consumption of alcohol, exercise, smoking, and behavioral and hormonal correlates of stress, all of which may affect fecundability. We have, though, reviewed a wide range of factors which contribute to fecundability and identified several points of potential interaction between the behavioral and biological determinants. We expect that our future understanding of these processes will be enhanced by empirical work and modeling efforts which also interact to draw upon the insights provided by each.

Behavior↗
PubMed2004

Platelet-activating factor receptor deficiency delays elimination of adult worms but reduces fecundity in Strongyloides venezuelensis-infected mice.

We describe the parasitological kinetics and histopathological and immunological alterations in platelet-activating factor receptor-deficient (PAFR(-/-)) and wild-type mice after a single Strongyloides venezuelensis infection (subcutaneous inoculation of 500 L3 larvae). There was no difference in the numbers of worms that reached and became established in the small intestines of PAFR(-/-) and wild-type mice. However, at 12 days after infection, significantly more worms were recovered from PAFR(-/-) mice. Although PAFR(-/-) infected mice showed a delay in elimination of adult worms, worms established in the small intestine of these mice produced a significantly lower number of eggs due to a reduction in worm fecundity. There were also significant reductions in the number of circulating and tissue eosinophils and tumor necrosis factor levels in the small intestines of PAFR(-/-) mice infected for 7 days compared to the number and level in wild-type mice. Histological analysis confirmed the reduced inflammatory process and revealed that the PAFR(-/-) mice had a smaller number of goblet cells. The concentrations of the type 2 cytokines interleukin-4 (IL-4), IL-5, and IL-10 were lower in small intestine homogenates and in supernatants of antigen-stimulated lymphocytes from spleens or mesenteric lymph nodes of PAFR(-/-) mice than in the corresponding preparations from wild-type mice. Thus, in S. venezuelensis-infected PAFR(-/-) mice, decreased intestinal inflammation is associated with enhanced worm survival but decreased fecundity. We suggest that although a Th2-predominant inflammatory response decreases worm survival, the worm may use factors produced during this response to facilitate egg output and reproduction. PAFR-mediated responses appear to modulate these host-derived signals that are important for worm fecundity.

Animals↗
PubMed2004

Miscarriage but not fecundity is associated with progression of joint destruction in rheumatoid arthritis.

OBJECTIVE: To determine whether reproductive history before disease onset is associated with severity of joint destruction in rheumatoid arthritis. METHODS: A special early arthritis clinic (EAC) was established at the department of rheumatology of Leiden University Medical Centre. General practitioners were encouraged to refer patients with joint complaints to this clinic, where the diagnosis of rheumatoid arthritis was made by a rheumatologist. In all, 113 female patients with definite rheumatoid arthritis were included in this study. A structured questionnaire was administered and joint damage was assessed by sequential x rays of the hands and feet, using the modified Sharp score. RESULTS: The length of time of unprotected intercourse until first pregnancy (fecundity) was comparable with data from earlier studies, with 16% of the patients reporting a time to first pregnancy of more than 12 months. Fecundity did not reflect the extent of joint damage over time. The miscarriage rate was 15% per pregnancy, comparable to population figures (12-15%). A significant increase in joint damage over a two year follow up was found in patients with rheumatoid arthritis who had experienced at least one miscarriage compared with those who had never had a miscarriage (mean modified Sharp scores at 2 years, 24 (95% confidence interval, 15 to 32) and 16 (10 to 23), respectively; p<0.05). At baseline, the Sharp scores were similar in the two subgroups. CONCLUSIONS: Miscarriage before disease onset but not fecundity is associated with the progression of joint damage in rheumatoid arthritis.

Abortion, Spontaneous↗
PubMed1993

Fat and female fecundity: prospective study of effect of body fat distribution on conception rates.

OBJECTIVES: To study the effect of body fat distribution in women of reproductive age on fecundity. DESIGN: Prospective cohort study of all women who had entered a donor insemination programme. SETTING: One fertility clinic serving a large part of the midwest of the Netherlands. SUBJECTS: Of 542 women attending the clinic for artificial insemination for the first time, 500 women were eligible for study. MAIN OUTCOME MEASURES: Probability of conception per cycle and number of insemination cycles before pregnancy or stopping treatment. RESULTS: A 0.1 unit increase in waist-hip ratio led to a 30% decrease in probability of conception per cycle (hazard ratio 0.706; 95% confidence interval 0.562 to 0.887) after adjustment for age, fatness, reasons for artificial insemination, cycle length and regularity, smoking, and parity. Increasing age was significantly related to lower fecundity (p < 0.05); very lean and obese women were less likely to conceive (p < 0.10) as were women with subfertile partners (p < 0.10). All other exposure variables were not significantly related to fecundity. CONCLUSIONS: Increasing waist-hip ratio is negatively associated with the probability of conception per cycle, before and after adjustment for confounding factors. Body fat distribution in women of reproductive age seems to have more impact on fertility than age or obesity.

Adipose Tissue↗
PubMed2004

Decreased fecundity among male lead workers.

AIMS: To investigate time to pregnancy (TTP) in male lead workers in order to determine the dose-response relation between blood lead and decreased fecundity. METHODS: A total of 163 currently employed married male lead battery workers were classified into five categories of exposure based on questionnaire information and annual individual blood lead measurement. Information pertaining to the TTP was collected using personal interviews with 133 men and their spouses, with 280 valid pregnancies. The fecundability ratios (FRs) were calculated with the Cox discrete proportional hazard regression technique to evaluate the effects of lead exposure. RESULTS: After other factors associated with TTP were controlled for, there was a dose-response relation between blood lead level and TTP. The measured FRs were 0.90 (95% CI 0.61 to 1.34), 0.72 (0.46 to 1.11), 0.52 (0.35 to 0.77), and 0.40 (0.27 to 0.59) for concurrent blood lead levels of <20, 20-29, 30-39, and > or =40 microg/dl, respectively. Paired self comparison was also performed for 41 couples that had pregnancies prior to lead exposure and pregnancies with male occupational lead exposure. The TTP was prolonged for 0.15 cycles by a 1 microg/dl increase in blood lead. CONCLUSIONS: These results corroborate the hypothesis that a raised blood lead level affects fecundity. A blood lead level of less than 40 microg/dl may still significantly prolong TTP.

Adolescent↗
PubMed2002

Host plant quality and fecundity in herbivorous insects.

Host plant quality is a key determinant of the fecundity of herbivorous insects. Components of host plant quality (such as carbon, nitrogen, and defensive metabolites) directly affect potential and achieved herbivore fecundity. The responses of insect herbivores to changes in host plant quality vary within and between feeding guilds. Host plant quality also affects insect reproductive strategies: Egg size and quality, the allocation of resources to eggs, and the choice of oviposition sites may all be influenced by plant quality, as may egg or embryo resorption on poor-quality hosts. Many insect herbivores change the quality of their host plants, affecting both inter- and intraspecific interactions. Higher-trophic level interactions, such as the performance of predators and parasitoids, may also be affected by host plant quality. We conclude that host plant quality affects the fecundity of herbivorous insects at both the individual and the population scale.

Animals↗
PubMed1989

Hypergravity and ageing in Drosophila melanogaster. 1. Fecundity.

In Drosophila melanogaster daily fecundity has been recorded throughout life of flies kept at various gravity levels (1-5 g). Hypergravity (HG) did not decrease total fecundity but modified its expression during life. The 1 g group could be opposed to the various HG groups, i.e. a clear regression of the various fecundity items on the HG level could not be disclosed. Results are discussed in relation with Pearl's rate of living theory.

Aging↗
PubMed1994

Cycle fecundity in baboons of proven fertility with minimal endometriosis.

To the best of our knowledge this is the first prospective study in nonhuman primates of proven fertility in the wild, which compares fertility between animals with spontaneous minimal endometriosis and those with a normal pelvis. During 7 months 13 female baboons were exposed to males and all pregnancies were terminated by hysterotomy. A diagnostic laparoscopy was performed to assess the presence of pelvic endometriosis at the end of the fertility trial. Sixty-one percent of the baboons became pregnant at least once and the cycle fecundity was 21%. No obvious difference was found between baboons with (n = 7) and without endometriosis (n = 6) in either pregnancy rate (57 and 67%, respectively) or cycle fecundity (18 and 24%, respectively). These data suggest that in baboons with spontaneous minimal endometriosis the cycle fecundity is not grossly reduced.

Animals↗
PubMed2005

Endometriosis in adolescence: a long-term follow-up fecundability assessment.

OBJECTIVE: A long-term, follow-up study comparing mild and severe forms of endometriosis and their fecundability, on 28 women diagnosed with endometriosis in adolescence. METHODOLOGY: Twenty-eight patients were identified from a prospective cohort of 52 adolescents (ages 12 to 18 years) with operative diagnosis of endometriosis between July 1993 and December 1995. All patients presented with chronic pelvic pain unresponsive to conservative medical management. Diagnosis of pregnancy was made by sonographic identification of intrauterine pregnancy, positive serum human chorionic gonadotropin or pathological confirmation of products of conception. Patients were categorized as fertile or sub-fertile by having > 12 months of unprotected intercourse without conception. Follow-up was done for 8.6 years. RESULTS: Staging of endometriosis was performed according to the American Society for Reproductive Medicine standards. Stage I = 14.3%; Stage II = 39.3%; Stage III = 42.8%; Stage IV = 3.6%. Fecundability rates in each stage were statistically significant: Stage I (75%), Stage II (55%), Stage III (25%), Stage IV (0%) (p < .05). Rates of spontaneous abortion were not statistically significant. CONCLUSION: In our cohort, even at the earliest point in the natural life cycle of endometriosis there is an inverse relationship between stage of disease at diagnosis and fecundability.

Adolescent↗
PubMed2001

Is an elevation in basal follicle-stimulating hormone levels in unexplained infertility predictive of fecundity regardless of age?

An elevation in follicle-stimulating hormone (FSH) levels is considered to reflect lowered ovarian function, resulting in poor fecundity in infertile women. However, it remains to be clarified whether or not the significance of FSH levels applies equally to all women irrespective of age. The objective of the present study is to compare basal FSH levels in infertile women who conceived or not after stratification by age. A total of 144 infertile women between ages 25 and 45 who underwent infertility treatment due to unexplained infertility in the University of Tokyo Hospital were included in the retrospective study. Subjects were divided by age into two groups, < 38 (n=98) vs > or = 38 (n=46) years, with ages ranging from 25 to 37, and from 38 to 45, respectively. Blood samples were collected in early follicular phase (day 4-6) for assessment of basal levels of LH, FSH, and PRL. In the older group, pregnant cases had significantly lower FSH levels (6.07 +/- 2.83 mIU/ml) than nonpregnant cases (9.60 +/- 3.67 mIU/ml), whereas no difference in basal FSH levels was observed between pregnant and nonpregnant cases in the younger group. Basal FSH levels of pregnant cases in the older group were significantly lower than those of pregnant cases in the younger group (8.26 +/- 2.95 mIU/ml). Basal LH and PRL levels were not related to fecundity in either group. Thus, an increase in basal FSH levels as a predictor of fecundity should be considered in the context of age.

Adult↗
PubMed2004

Comparative study of the fecundity and fertility of Biomphalaria glabrata (Say, 1818) and Biomphalaria straminea (Dunker, 1848) in a laboratory through self-fertilization and cross-fertilization.

The aim of this study was to compare the fecundity and fertility of B. glabrata and B. straminea by cross- and self-fertilization. To attain this objective, laboratory-raised strains of B. glabrata and B. straminea were used. The former originated from natural breeding grounds in the municipality Paulista, state of Pernambuco, Brazil. The latter originated from irrigation ditches in the municipality of Petrolândia, in the same state. Snail populations of B. glabrata and B. straminea were maintained for 240 days in laboratory. Their fecundity was evaluated by noting the number of egg-masses, eggs and eggs per mass. Their fertility was evaluated by the number of viable eggs and the hatching rate. B. straminea was markedly more fecund than B. glabrata through cross- and self-fertilization, namely: greater egg-mass; higher egg production and more eggs per mass. Regarding fertility, there seemed to be no preferential period for occlusion to occur or a trend in the rhythm of producing viable eggs.

Animals↗
PubMed2001

Fecundity of Hoplopleura scapteromydis (Phthiraptera: Anoplura, Hoplopleuridae), ectoparasite of Scapteromys aquaticus (Rodentia: Muridae) in Rio de La Plata marshlands, Argentina.

Density and age structure of lice collected from captured Scapteromys aquaticus rodents were studied to estimate the fecundity of Hoplopleura scapteromydis. The number of eggs with a visible embryo inside (E), nymphs (N), adult males (AM), and adult females (AF) were recorded for each rodent. For the ith rodent, the fecundity of H. scapteromydis, F(i), was estimated as F(i) = [[E(i) + N(i)]/2]/AF(i)/T, where T represents the period of preimaginal development (unknown and arbitrarily considered as T = 1), and the sex ratio of the preimaginal stages was supposed to be 1:1. In order to look for density-dependent effects, F(i) was plotted against AM(i), this being an independent estimation of infrapopulation density. The number of rodents suitable for AF and AM calculations was 38 (57% of the parasitized animals). Almost 95% had a low-to-moderate louse burden (1 < AM < 30) and were captured every season, whereas only 3% had a heavy (61 < AM < 70, captured in winter) or very heavy (AM > 80, captured in summer) louse burden. The extreme values of F were 0.63 and 18 (1.3 and 36 if both sexes were considered). High-to-moderate F-values (F > 5) were estimated in only 5 rodents that exhibited low louse density, whereas low F-values (F < 5) were found at all louse densities. Notwithstanding the tendency toward an inverse relationship between fecundity and infrapopulation density, the correlation was not significantly different from 0.

Animals↗
PubMed2006

Acute exposure of adult male rats to dietary phytoestrogens reduces fecundity and alters epididymal steroid hormone receptor expression.

Phytoestrogens are plant-derived compounds with oestrogenic activity. They are common in both human and animal diets, particularly through soy-based foods. This study assessed whether exposure of adult male rats to a high phytoestrogen diet for 3-25 days affected their fertility, and assessed possible mechanisms through which phytoestrogens may disrupt fertility. Adult males, fed a high phytoestrogen diet for 3 days, demonstrated significantly reduced fecundity. This effect was transient, with fecundity returning to control levels by day 12. The expression of oestrogen receptor-alpha and androgen receptor mRNA was increased in the initial segment of the epididymis, but decreased in the cauda epididymis following 3 days on the high phytoestrogen diet. Epididymal sperm counts cannot account for the reduction in fertility at day 3. However, lipid peroxidation of epididymal sperm was significantly increased in animals fed a high phytoestrogen diet for 3 days. Disruption of the steroid regulation of the epididymis by phytoestrogens may alter its function, resulting in decreased quality of sperm, and thereby reducing fecundity.

Animals↗
PubMed2006

Independent effects of food and predator-mediated processes on annual fecundity in a songbird.

We investigated the relative importance and interaction of ecological processes affecting annual fecundity in birds by simultaneously manipulating food availability and nest predation risk in a small songbird, the Wrentit (Chamaea fasciata). From 2000 to 2002 we provided supplemental food to individual Wrentit territories, and during 2002 we altered nest predation risk by providing supplemental food to their principal predators, Western Scrub-Jays (Aphelocoma californica). These experiments were conducted during a period of high interannual variation in rainfall, with 2002 being one of the driest years on record. Food-supplemented Wrentits in a normal predation environment produced an average of 0.54 more fledglings per year than control pairs over the three breeding seasons. During the feeding plus predation manipulation experiment, Wrentit food supplementation and lowered nest predation risk each independently increased the probability that a Wrentit pair would fledge young; however, the interaction between food supplementation and altered nest predation risk was not significant. Thus, even in an extreme drought year, both food and nest predation had equal but independent effects on reproductive success and annual fecundity. Combining supplemental food with reduced nest predation did not result in a synergistic increase in annual fecundity, primarily because Wrentits did not produce multiple broods. Our results suggest that whether food and predation have additive or synergistic effects on reproductive success depends on the life history of the species and the environment in which they live.

Analysis of Variance↗
PubMed2006

Effects of an organophosphorous insecticide on survival, fecundity, and development of Hylyphantes graminicola (Sundevall) (Araneae: Linyphiidae).

Abstract-The effects of an organophosphorous insecticide, methamidophos, on fecundity and development of the spider Hylyphantes graminicola (Sundevall) (Araneae: Linyphiidae) were assessed under laboratory conditions. Susceptibility of adults of both sexes to the insecticide and its influence on fecundity of females and development of offspring were investigated. At 48 h after topical application in adults, the median lethal dose (LD50) and 10% lethal dose (LD10) were 0.35 and 0.12 microg/spider, respectively, for males and 0.52 and 0.16 microg/spider, respectively, for females. Methamidophos had detrimental effects on fecundity of females; number of eggs per clutch, total egg mass, and clutch size decreased significantly. The hatching rate of eggs from LD10-treated females was slightly higher than the rate in the controls, but the hatching rate of eggs from LD50-treated females was lower than the rate in the controls. However, no significant differences were observed in hatching time and development time across treatments. Development time of spiderlings from LD50-treated females was significantly longer than the time in the controls, and body sizes of the first spiderlings from insecticide-treated females were larger than those in the controls. However, matured offspring were smaller than those in the controls. It was concluded that methamidophos has long-term effects on H. graminicola, and that this may affect the development of spider populations in the field.

Animals↗