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PubMed1986

Experimental infection of Tribolium confusum (Coleoptera) by Hymenolepis diminuta (Cestoda): host fecundity during infection.

Some effects of Hymenolepis diminuta on the fecundity of Tribolium confusum are described. Host fecundity is observed to be reduced exponentially with increasing parasite burden/host, although there are differences in the ability of individual hosts to respond to parasitism. Of particular interest is the finding that host fecundity is greatly reduced in young beetles on or by day 14 post-infection (p.i.). This age-related reduction in host fecundity is discussed in relation to the population dynamics of this host-parasite relationship.

Aging↗
PubMed2002

Fecundity and life span in transgenic Drosophila melanogaster overexpressing hsp70.

In the present study, we investigated the effect of hsp70 overexpression on some life history components in transgenic fruit flies. We measured life span in mated flies and fecundity in flies subjected or not subjected to a heat shock inducing hsp70. Heat shock increased life span of the parental line, but not of the transgenic lines. Genetic manipulation of the flies altered their fecundity, but the heat shock had no effect on fecundity. To conclude, we have observed some costs of genetic manipulation by itself on life span and fecundity. However, the overexpression of the hsp70 extra copies by the exposure to heat did not alter the studied variables.

Analysis of Variance↗
PubMed2006

Interleukin-10 promoter polymorphisms in male and female fertility and fecundity.

Interleukin-10 (IL10) is assumed beneficial for a successful pregnancy; it may increase fertility and fecundity. Allele frequencies of IL10 polymorphisms at position -2849, -1082 and -592 were analyzed in association with a past history of fertility and fecundity in men and women of at least 85 years old. Fertility was decreased in association with the -2849 A allele in females; 27% of the AA genotype carriers produced no offspring in marriage compared to 14% of the G allele carriers (odds ratio (OR): 2.2, 95% confidence interval (CI): 1.2-4.2, P=0.01). Effective fecundability was decreased in association with the -2849 A allele in females; 7% of female -2849 AA genotype carriers had a child within 371 days of marriage (therefore, conceived within 3 months of marriage) compared to 28% of female G allele carriers (OR: 0.2, 95% CI: 0.04-0.7, P=0.01). This suggests an association between the -2849 AA genotype and a decreased fertility and fecundity in females.

Aged, 80 and over↗
PubMed2000

Size-specific fecundity and the influence of lifetime size variation upon effective population size in Abies balsamea.

The hierarchy of plant size often present in dense populations of plants and the close correlation found between size and fecundity can result in an unequal distribution of fecundity, which reduces the ratio of effective population size/census number (Ne/N). Such an effect has been found previously in annuals, but no study has hitherto tested for the effect in the lifetime fecundity variation of a perennial population. We use the demographically stable size distribution to be found in natural, wave-regenerating populations of balsam fir, Abies balsamea, in order to estimate Ne/N. In both wave-regenerating and normal forests our estimated values of Ne/N were about twice those previously reported for annuals. We suggest that fecundity variance is expected to be smaller in trees and other long-lived perennials than in annuals because density-dependent mortality operates more strongly in the prereproductive phase of long-lived plants.

Fertility↗
PubMed1990

Artificial insemination of Cashmere goats: effects on fertility and fecundity of intravaginal treatment, method and time of insemination, semen freezing process, number of motile spermatozoa and age of females.

The experiments, using a total of 1833 Cashmere does, were conducted to examine the effects on fertility and fecundity of intravaginal treatment for control of ovulation, time of insemination by cervical and laparoscopic methods, semen processing in pellets and straws, and number of frozen-thawed motile spermatozoa. Adult does (greater than or equal to 2.5 years) that had previously kidded were inseminated into the cervix, and maiden (kid: 6-8 months; hogget: 18 months) and adult does were inseminated laparoscopically. The rates of pregnancy determined by ultrasonic scanning (75-80 days after insemination) for cervical (Experiment 1) and laparoscopic (Experiments 2 and 3) insemination were 39.1%, 63.6% and 52.1%. The number of motile spermatozoa did not affect fertility after cervical (80, 120 and 160 x 10(6) or laparoscopic (Experiment 2: 15, 30 and 60 x 10(6); Experiment 3:5, 10 and 20 x 10(6) insemination. The method of insemination or number of motile spermatozoa did not affect fecundity. With cervical insemination, fertility and fecundity improved with increasing depth of insemination into the reproductive tract. Intravaginal sponges containing fluorogestone acetate and controlled internal drug release (CIDR) devices containing progesterone were equally effective for control of ovulation when combined with an injection of pregnant mare's serum gonadotrophin (PMSG; 200 i.u.) before insemination. Fertility was higher when does were inseminated before than after ovulation. After laparoscopic insemination, results were similar for semen frozen as pellets and in straws, and for 3-, 6- and 24-fold pre-freezing dilution of semen. For kid, hogget and adult does in Experiment 3, pregnancy rates were 34.0%, 55.4% and 63.9% and rates of fecundity were 1.17, 1.22 and 1.27 fetuses/pregnant doe.

Administration, Intravaginal↗
PubMed1996

Relative effects of female fecundity and male mating success on fertility selection in Drosophila pseudoobscura.

The fertility component of natural selection acting on chromosomal inversions in two experimental populations of Drosophila pseudoobscura was subdivided into the effects of female fecundity and male mating success. The offspring of the three female genotypes could be distinguished by their mitochondrial DNA haplotypes, thus permitting a direct measurement of the relative fecundities of the female genotype. The effects of male mating success on inversion frequency were measured by comparing inversion frequencies in parents and their offspring. Selection by fertility caused significant changes in inversion frequency in both populations. In one population, the changes in inversion frequency due to female fecundity and to male mating success were comparable. In the other population, however, the changes in inversion frequency due to male mating success were considerably larger than those due to female fecundity. The difference between the two populations underscores the intrinsic variability of the fertility component of fitness.

Animals↗
PubMed2002

Host location, survival and fecundity of the Oriental rat flea Xenopsylla cheopis (Siphonaptera: Pulicidae) in relation to black rat Rattus rattus (Rodentia: Muridae) host age and sex.

Host choice and fecundity are two factors that may contribute to the variation in flea counts observed when assessing the potential risk of flea-borne transmission of pathogens from rodents to humans. Using the black rat, Rattus rattus Linnaeus, as host the effects of age and sex on host choice and fecundity of the Oriental rat flea, Xenopsylla cheopis Rothschild, were examined experimentally at 25 degrees C and 80% rh. During the first two days of emergence from cocoons, female fleas dominated the sex ratio by 4:1 but from the third day onwards this switched to a male-dominated sex ratio of 4:1. The sex of the flea did not influence their host-seeking behaviour. Newly emerged fleas of both sexes were not influenced by the rat's presence and at seven days old both sexes demonstrated similar levels of attraction toward the rat host. The sex of the rat did not affect flea host-seeking behaviour. There was a 50-70% decline in the initial number of adult fleas during the first week after their release onto a rat host, and this decline was greatest on juvenile rats. Flea fecundity was also significantly lower on juvenile rat hosts but no differences due to the sex of the rat were observed. This experimental study supports the hypothesis that differences in flea count due to host sex, reported in field surveys, result from sexual differences in host behaviour and not from discriminatory host-seeking behaviour by X. cheopis. Differences in flea count due to host age may be affected by differences in X. cheopis fecundity, which may itself be mediated by host behaviour such as grooming.

Animals↗
PubMed2005

Individual fecundity and senescence in Drosophila and medfly.

Evolutionary theory postulates that there should be a robust relationship between fecundity and longevity. Prior work has generally supported this concept, but has not shed much light on the mechanisms at play. In preceding work, we have developed and verified a mathematical model of Drosophila melanogaster female fecundity based on the analysis of empirical studies independently done by several different laboratories. Then we applied this technique to Mediterranean fruit fly (medfly) populations. In this article we analyze associations between individual longevity and the parameters of individual fecundity pattern in Drosophila and medfly. We cluster both Drosophila and medfly individuals by life span and discuss the differences. It allows us to demonstrate that only one fecundity-related parameter is associated with longevity in Drosophila, whereas two such parameters can be found in medflies. This difference demonstrates different ways of aging in various Diptera species. Finally, we discuss the possible implications of this finding.

Aging↗
PubMed1997

Repeating episodes of low fecundability. A multicentre European study. The European Study Group on Infertility and Subfecundity.

Many reproductive failures tend to repeat themselves within the same couple. Whether fecundability (the probability of conceiving in a given number of menstrual cycles) follows the same pattern is studied using data from the European Studies on Infertility and Subfecundity (ESIS): 6630 women were interviewed on 'time to pregnancy' (TTP) and other aspects of their pregnancy history. Surveys were conducted between 1991 and 1994 in seven regions from five European countries. Furthermore, the pattern of fecundability in this population was compared with results from computer simulations based upon a population with fixed fecundability parameters. Results from ESIS speak in favour of the stability of fecundability in the relatively short reproductive life of a couple. However, a substantial proportion of couples with up to two events of subfecundability (TTP >9.5 months) became pregnant shortly after trying again. This finding calls for reservation in starting expensive and/ or unpleasant diagnostic procedures at an early stage when a couple tries to become pregnant again.

Adult↗
PubMed1998

Seasonal variation in human fecundability.

Seasonality of effective fecundability was investigated in a cohort of 402 women born in or near Rotterdam, The Netherlands, between 1873 and 1887, and married before the age of 40 years. Applying a newly developed method allowing simultaneous control for inherent couple fecundability, numbers at risk of pregnancy, and multiple confounders, we found a trend towards higher fecundability during the first half of June and the first half of December (P = 0.06). Seasonality of effective fecundability appeared to be strongest for women who married at <20 years of age. Potentially important implications for the study of seasonality of adverse reproductive outcome are discussed.

Adolescent↗
PubMed2000

The relationship between fertility potential measurements on cryobanked semen and fecundity of sperm donors.

Sperm penetration assay (SPA) scores obtained from cryobanked semen were correlated with therapeutic insemination (TI) fecundity in a group of established sperm donors, thereby evaluating the efficacy of the SPA in screening donors for sperm banking. While the SPA has been used to separate fertile from infertile males, we altered assay conditions to use frozen semen and to distinguish performance among fertile donors. Three frozen ejaculates from 11 pregnancy-proven donors were analysed. Of 905 TI cycles, 275 recipients achieved 95 pregnancies. There were no significant relationships between fecundity and donor semen, washed sperm parameters, sperm recoveries or recipient age. A significant relationship was revealed between mean SPA scores (range 8.7-66.6 penetrations/ovum) and donor fecundity (range 0.04-0.16, P < 0.03). Sperm concentration was varied in an effort to establish the most sensitive test condition. Using 0.25x10(6) motile spermatozoa/ml, a highly significant relationship was observed (P < 0.002). The four donors with the lowest SPA scores achieved the four lowest fecundities. It is concluded that a modified SPA can be used on frozen donor semen to estimate donor fertility potential. If applied routinely in donor semen banking, poor quality applicants could be excluded, thereby increasing pregnancy rates while decreasing donor screening costs.

Adult↗
PubMed2004

Is previous aberrant reproductive outcome predictive of subsequently reduced fecundity?

BACKGROUND: Effect of past reproductive performance on subsequent fecundity is uncertain. METHODS: A total of 2983 consecutive pregnant women self-completed questionnaires about time to pregnancy (TTP), pregnancy planning, previous pregnancies, contraceptive use, age, and individual/lifestyle variables. Outcome measures were: TTP, conception rates (CR) and, subfecundity odds ratio (OR; with 95% confidence intervals) before and after each outcome of last pregnancy. RESULTS: After miscarriage, TTP was longer than before miscarriage [2.1 (1.4-3.0), P < 0.001] and than TTP after livebirth [OR = 2.1 (1.6-2.6), P < 0.001]. Also subfecundity OR after miscarriage increased [1.7 (1.2-2.4), 1.8 (1.2-2.5), P = 0.001, 0.002 respectively]. This effect was more evident in older and obese women. Compared with livebirth, time to ectopic pregnancy (EP) was longer [OR = 13.8 (1.8-108.5), P = 0.001] but TTP after EP was not significantly different. Subfecundity OR relative to livebirth were 12.8 (3.6-45.0) (P<0.001) before, and 3.9 (1.4-11.0) (P=0.01) after, EP. The CR after EP increased 3-fold (1.1-8.3) over those prior to EP. Time to the terminated pregnancies even without contraceptive failures was shorter than that to livebirth [OR = 0.5 (0.3-0.7), P = 0.001] and than TTP after termination [0.35 (0.1-0.8), P = 0.001]. Also subfecundity OR increased after termination [7.2 (1.8-29.7), P = 0.02]. CONCLUSIONS: Miscarriers should be counselled about short-term reduction in subsequent fecundity, and earlier investigations should be considered in those who have other potential risk factors for reduced fertility. Further studies are required to clarify the relatively favourable effect on fecundity following EP and the relative reduction in fecundity after termination of pregnancy.

Abortion, Induced↗
PubMed2006

Gender-specific association of the factor V Leiden mutation with fertility and fecundity in a historic cohort. The Leiden 85-Plus Study.

BACKGROUND: Factor V Leiden (FVL, Arg506Gln) mutation may facilitate embryo implantation and increase fertility and fecundity. This was studied in subjects who were of childbearing age in a time with minimal fertility control without modern contraceptive methods. METHODS: From 1986 to 1999, 1502 inhabitants of Leiden, The Netherlands, reaching the age of 85 years were enrolled in the Leiden 85-Plus Study. Of 1176 subjects the FVL status was analysed, in 365 male and 811 female subjects. RESULTS: The FVL carrier rate was 4.3%. Fertility was not affected by FVL status. In male subjects, fecundity (interval between marriage and birth of first child) was significantly increased in FVL carriers; 67% of male FVL carriers had a child within 371 days of marriage (therefore conceived within 3 months of marriage), compared with 19% of male non-carriers [relative risk (RR), 3.5; 95% confidence interval (CI), 2.1-5.7; P < 0.001]. Within 6 months of marriage, 75% of male FVL carriers had conceived a child compared with 34% male non-carriers (RR, 2.2; 95% CI, 1.5-3.2; P = 0.01). In female subjects, fecundity was not influenced by FVL status. CONCLUSION: Fecundity is increased in male FVL carriers; in female subjects, no such association was observed.

Aged, 80 and over↗
PubMed1994

The influence of occupational physical activity on the menstrual cycle and fecundability.

We examined the influence of the level of occupational physical activity per working hour (intensity score) and per working day (fatigue score) on menstrual function and fecundability in a population of 260 nonmedical female workers who were employed at 39 Dutch hospitals and were planning a pregnancy. We studied the influence of the intensity and fatigue scores as such and in combination with unfavorable working hours (before 8:00 am or after 6:00 pm) and high working speed (working at high speed for more than 50% of the time). The data did not reveal a clear relation between the occupational physical activity levels (representing an estimated energy requirement of up to 3 times the basal metabolic rate) and menstrual function, but the presence of a small effect could have been missed. The fecundability of women with a high fatigue score, particularly in association with unfavorable working hours, was lower than that of women with a low fatigue score (fecundability odds ratio = 0.37; 95% confidence interval = 0.18-0.77). Moderate levels of physical activity, as found in cleaners, kitchen staff, and clerical workers at hospitals, appear to affect the female reproductive system. Fecundability, as measured by the time to pregnancy, seems to be a more sensitive parameter for these biological changes than menstrual function.

Adolescent↗
PubMed1999

Fecundability in relation to body mass and menstrual cycle patterns.

Few studies have investigated the association between body mass index and fecundability, that is, the ability to conceive in a menstrual cycle, among fertile women with normal menstrual cycle pattern. We examined the independent and combined effects of duration and regularity of the menstrual cycle, body mass index, and fecundability from records on pregnant women attending antenatal care at Odense University Hospital, Denmark, between 1972 and 1987. We included only the first birth of each woman who had planned pregnancies and no pre-pregnancy disease (N = 10,903). We estimated the fecundability odds ratio (FR) as the odds of conception in a menstrual cycle. After adjusting for confounders, the fecundability for women with a body mass index >25 kg/m2 was lower than for women with a body mass index of 20-25 kg/m2 [FR = 0.77; 95% confidence interval (CI) = 0.70-0.84]. FR was lower for women with long (>35 days) (FR = 0.74; 95% CI = 0.63-0.87) or irregular cycles (FR = 0.78; 95% CI = 0.70-0.87), even when their body mass index was within the normal range (20-25 kg/m2) and/or their cycles were regular.

Body Mass Index↗
PubMed2003

The correlation of fecundability among twins: evidence of a genetic effect on fertility?

BACKGROUND: Numerous rare genetic conditions are known to influence fecundability in both males and females. It is less clear to what extent more subtle genetic differences influence fecundability on a population level. METHODS: In 1994 a population-based survey was conducted among Danish twins born 1953-1982. Fecundability was assessed as the waiting time to pregnancy at the first attempt to achieve a pregnancy. RESULTS: The reported time to pregnancy for males was slightly shorter than for females but there were no sex differences in intrapair similarity. We found an intrapair correlation in time to pregnancy for 645 monozygotic twin pairs (r = 0.22; 95% confidence interval = 0.12 to 0.32), but no intrapair correlation for 826 like-sex dizygotic twin pairs (r = 0.00; 95% confidence interval = -0.09 to 0.10). CONCLUSIONS: The correlation in time to pregnancy for monozygotic twins suggests genetic factors, although similarities in reporting behaviors could also be contributing to the correlation. The lack of correlation in time to pregnancy for dizygotic twins indicates that possible genetic factors of importance for fecundabililty are acting nonadditively. Hence, it may prove difficult to identify specific gene variants that influence fecundability on a population level if their effects depend on gene-gene interactions.

Age Factors↗
PubMed2004

Parasite-mediated reduction in fecundity of mountain hares.

Mountain hare populations in Scotland exhibit regular 10 year fluctuations in abundance. Simple models of host-parasite population dynamics suggest that parasite-mediated reductions in host fecundity can cause a transition from stable to cyclic host population dynamics. We tested the hypothesis that parasites reduce hare fecundity by experimentally reducing parasite burdens and recording female survival, body condition and fecundity. We captured 41 adult female hares in October 2002; 22 were treated with Ivermectin to remove parasites and 19 were left untreated as controls. The treated and untreated hares were culled in May 2003 together with a second control group of nine unhandled hares. Treatment with Ivermectin significantly reduced the abundance of Trichostrongylus retortaeformis and increased-the fecundity of the hares, but had no measurable effect on body condition or over-winter survival. These results are consistent with the hypothesis that parasites may be a contributory cause of cycles in populations of mountain hares.

Animals↗
PubMed2006

Having it all: historical energy intakes do not generate the anticipated trade-offs in fecundity.

An axiom of life-history theory, and fundamental to our understanding of ageing, is that animals must trade-off their allocation of resources since energy and nutrients are limited. Therefore, animals cannot "have it all"--combine high rates of fecundity with extended lifespans. The idea of life-history trade-offs was recently challenged by the discovery that ageing may be governed by a small subset of molecular processes independent of fitness. We tested the "trade-off" and "having it all" theories by examining the fecundities of C57BL/6J mice placed onto four different dietary treatments that generated caloric intakes from -21 to +8.6% of controls. We predicted body fat would be deposited in relation to caloric intake. Excessive body fat is known to cause co-morbidities that shorten lifespan, while caloric restriction enhances somatic protection and increases longevity. The trade-off model predicts that increased fat would be tolerated because reproductive gain offsets shortened longevity, while animals on a restricted intake would sacrifice reproduction for lifespan extension. The responses of body fat to treatments followed our expectations, however, there was a negative relationship between reproductive performance (fecundity, litter mass) and historical intake/body fat. Our dietary restricted animals had lower protein oxidative damage and appeared able to combine life-history traits in a manner contrary to traditional expectations by having increased fecundity with the potential to have extended lifespans.

Animals↗