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PubMedDate not supplied

The age pattern of fecundability: an analysis of French Canadian and Hutterite birth histories.

This paper analyzes the age pattern of effective fecundability from populations with no evidence of deliberate fertility control using a new convolution model of fecundability. The analysis is based on a sample of Hutterite birth histories from the mid-20th century, and birth histories of French Canadians from the 17th and 18th centuries. The main findings are as follows: 1) the level of effective fecundability is higher among the French Canadians compared to the Hutterites; 2) effective fecundability peaks at age 20 for the Hutterites, and in the early to mid-20s for the French Canadians; 3) Hutterite effective fecundability declines almost linearly from age 20 to 45, and French Canadian effective fecundability declines slowly from its peak to the early 30s, and more rapidly at older ages; and 4) the duration of postpartum amenorrhea is longer for the French Canadians than for the Hutterites. Because of the shorter periods of postpartum amenorrhea the Hutterites have about the same average number of children as the French Canadians, even though the French Canadians have higher effective fecundability.

Adolescent↗
PubMed2001

The evolution of trade-offs: effects of inbreeding on fecundity relationships in the cricket Gryllus firmus.

The evolution of traits is modulated by their interrelationships with each other, particularly when those relationships result in a fitness trade-off. In this paper we explore the consequences of genetic architecture on functional relationships between traits. Specifically, we address the consequences of inbreeding on these relationships. We show that the linear regression between two traits will not be affected if there is no dominance genetic variance in either trait, whereas the intercept but not the slope of the regression will change if there is dominance genetic variance in one trait only. We test the latter hypothesis using fecundity relationships in the cricket Gryllus firmus. Data from pedigree analysis and an inbreeding experiment show that there is significant dominance genetic variance in fecundity, but not head width (an index of body size) or dorsal longitudinal muscle (DLM) mass. Fecundity increases with head width, but decreases with DLM mass. As predicted, the intercepts of the regressions of fecundity on these two morphological traits decrease with inbreeding, but there is little or no change in slope. Gryllus firmus is wing dimorphic, with the macropterous (LW) morph having a lower fecundity than the micropterous (SW) morph. We hypothesize that the difference in fecundity arises primarily because of a competition for resources in the LW females between DLM maintenance (i.e., mass) and egg production. As a consequence, we predict that the fecundity within each morph should decline linearly with the inbreeding coefficient at the same rate in both morphs. The result of this will be a change in the relative fitness of the two morphs, that of the SW morph increasing with inbreeding. This prediction is supported. These results indicate that trade-offs will evolve and such changes will affect evolutionary trajectories by altering the pattern of relationships among fitness components.

Animals↗
PubMed2000

The effects of population size limitation on fecundity in mosaic populations of the clonal macrophyte Scirpus maritimus (Cyperaceae).

The clonal macrophyte Scirpus maritimus (Cyperaceae) propagates locally by rhizomes and reproduces sexually by achenes. The purpose of this paper was to examine whether in size-limited habitats in patchy and discrete marshes in two Mediterranean wetlands in southern France natural populations may suffer from a reduced maternal fecundity due to a deficit in outcross pollen. We first verified that S. maritimus suffers from a reduced fecundity when self-pollinated. At a site in the Camargue, mean fecundity (mean number of achenes per centimetre of spikelet) measured in 1995 and 1996 in seven and nine populations, respectively (surface area from 50 to 4500 m) increased significantly with population surface area in 1995 but not in 1996. In the second wetland at Roquehaute, which is composed of small ponds, fecundity was very low in all 12 local populations studied in 1996 (1.1 achenes per spikelet, SD = 1.2) and was not correlated with the population surface area (from 10 to 400 m). We performed a pollen supplementation experiment in five local populations at Roquehaute to determine whether this low fecundity may be due to a pollen limitation. A significant increase in fecundity after among-pond pollinations compared to within-pond pollinations indicated that local populations suffer from a deficit in outcross pollen, since each pond appears to contain one or a few number of clones (or incompatibility types). In S. maritimus, clonal spread may have a cost in terms of reduced fecundity in small habitats because each habitat is colonized by very few clones.

Journal Article↗
PubMed1986

The determinants of effective fecundability based on the first birth interval.

There are substantial differences in fecundability among nine developing countries in different parts of the world. In addition, within countries, later age at marriage has a clear, positive, nonlinear effect on fecundability. Women with higher education and those with more educated husbands have higher fecundability. Urban residents have higher fecundability than rural. The higher fecundability of more recent cohorts is the most consistent observation. Since those variables most frequently shown to have inverse relationships to fertility show direct relationships to fecundability within populations, the role of fecundability as a proximate variable in models of the determinants of fertility requires further specification.

Adult↗
PubMedDate not supplied

Impaired fecundity in the United States: 1982-1995.

CONTEXT: The 1995 National Survey of Family Growth (NSFG) provides new nationally representative data to test the accuracy of the commonly held assumption that impaired fecundity has been rising in the United States over the past decade. METHODS: Using data from the 1982, 1988 and 1995 rounds of the NSFG, trends in both the proportions and numbers of women with impaired fecundity and of those who received infertility services were examined. Multiple logistic regressions were carried out to estimate the effects of demographic characteristics on the likelihood of currently having impaired fecundity and of ever having received medical help for infertility. RESULTS: The proportion of U.S. women aged 15-44 who reported some form of fecundity impairment rose from 8% in 1982 and 1988 to 10% in 1995, an increase in absolute numbers from 4.6 million to 6.2 million women. Although the proportion of fecundity-impaired women who had ever sought medical help did not change between 1988 and 1995 (44%), the absolute numbers of such women grew by nearly 30%, from 2.1 million to 2.7 million. Women who had ever sought help for fertility problems were older and had a higher income than those who had not, and were more likely to be married. CONCLUSION: The dramatic increase in the numbers of U.S. women with impaired fecundity occurred because the large baby-boom cohort, many of whom delayed childbearing, had reached their later and less fecund reproductive years. This increase in both rates and numbers occurred across almost all age, parity, marital status, education, income, and race and ethnicity subgroups.

Adolescent↗
PubMedDate not supplied

Caffeine intake and fecundability: a follow-up study among 430 Danish couples planning their first pregnancy.

Fecundability has been defined as the ability to achieve a recognized pregnancy. Several studies on caffeine and fecundability have been conducted but have been inconclusive. This may be explained partly by lack of stratification by smoking. Furthermore, few researchers have tried to separate the effect of caffeine from different sources (coffee, tea, cola, and chocolate). Clearly, the relationship between caffeine and fecundability needs further research, given the high prevalence of caffeine intake among women of childbearing age. We examined the independent and combined effects of smoking and caffeine intake from different sources on the probability of conception. From 1992 to 1995, a total of 430 couples were recruited after a nationwide mailing of a personal letter to 52,255 trade union members who were 20 to 35 years old, lived with a partner, and had no previous reproductive experience. At enrollment and in six cycles of follow-up, both partners filled out a questionnaire on different factors including smoking habits and their intake of coffee, tea, chocolate, cola beverages, and chocolate bars. In all, 1596 cycles and 423 couples were included in the analyses. The cycle-specific association between caffeine intake and fecundability was analyzed in a logistic regression model with the outcome at each cycle (pregnant or not pregnant) in a Cox discrete model calculating the fecundability odds-ratio (FR). Compared to nonsmoking women with caffeine intake less than 300 mg/d, nonsmoking women who consumed 300 to 700 mg/d caffeine had a FR of 0.88 [95% confidence interval (CI) 0.60-1.31], whereas women with a higher caffeine intake had a FR = 0.63 (95% CI 0.25-1.60) after adjusting for female body mass index and alcohol intake, diseases of the female reproductive organs, semen quality, and duration of menstrual cycle. No dose-response relationship was found among smokers. Among males, the same decline in point estimates of the FR was present. Smoking women whose only source of caffeine was coffee (>300 mg/d) had a reduced fecundability odds-ratio (FR = 0.34; 95% CI 0.12-0.98). An interaction between caffeine and smoking is biologically plausible, and the lack of effect among smokers may be due to faster metabolism of caffeine. Our findings suggest that especially nonsmoking women who wish to achieve a pregnancy might benefit from a reduced caffeine intake.

Adult↗
PubMed1994

Cigarette smoking, alcohol consumption, and caffeine intake and fecundability.

BACKGROUND: In a prospective study the effect of the behavioral risk factors of both partners on fecundability was studied. METHODS: Information was collected on smoking habits, alcohol consumption, and caffeine intake (e.g. coffee, tea, and cola consumption) by interviewing 259 female nonmedical hospital workers, i.e., clerical staff, cleaners, kitchen and restaurant workers, and their partners, who were planning a pregnancy. The occurrence of pregnancy was tested prospectively during the 12 months after enrollment. RESULTS: Among the participants as well as among their partners, smoking a moderate number of cigarettes (1-10/day) was associated with higher fecundability (i.e., the probability of becoming pregnant each month) than among those not smoking (participant: OR = 1.4 (95% CI, 0.9-2.2); partner: OR = 2.1 (95% CI, 1.2-3.5)). The level of alcohol consumption in the female partner was not related to fecundability. However, in the male partner, there was a positive influence for drinking more than 10 alcoholic drinks per week compared with that observed for those drinking less than 5 (OR = 1.6; 95% CI, 1.0-2.4). Participants with a moderate caffeine intake (400-700 mg/day) showed a higher fecundability than those with a lower intake level (ORadjusted = 2.1 (95% CI, 1.2-3.7)). Heavy caffeine intake (> 700 mg/day) among partners was negatively related to fecundability when compared with the lowest intake level (ORadjusted = 0.6 (95% CI, 0.3-0.97)). CONCLUSIONS: This study does not support the hypothesis that moderate cigarette smoking, caffeine intake, and alcohol consumption have an adverse influence on fecundability.

Adolescent↗
PubMed2000

Mild winter temperatures reduce survival and potential fecundity of the goldenrod gall fly, Eurosta solidaginis (Diptera: Tephritidae).

We tested the hypothesis that mild winter temperatures are detrimental to the survival and reproductive potential of insects. We measured survival, body size, and potential fecundity of a freeze tolerant insect, the goldenrod gall fly (Eurosta solidaginis), after overwintering in the laboratory for ~3 mo. frozen at -22 degrees C, unfrozen at 0 degrees C, or unfrozen at 12 degrees C. Larvae held at 12 degrees C suffered high mortality (70%) and relatively low potential fecundity as adults (mean+/-SEM=199+/-11 eggs/female), while those held at 0 degrees C had both low mortality (11%) and high potential fecundity (256+/-15 eggs/female). Freezing (-22 degrees C) increased mortality (30% overall) but did not significantly reduce fecundity (245+/-13 eggs/female). Egg length and width were constant regardless of treatment group or female body size. Analysis of covariance indicated that reduced fecundity in the 12 degrees C group was related to reduced larval body weight following treatment. Patterns of larval weight loss in the experimental treatments were generally correlated with previous reports of latitudinal trends in weight loss through the winter. We conclude that mild winter temperatures may be detrimental to some overwintering insects, particularly species that do not feed following winter diapause. Low temperature and even freezing are beneficial, allowing conservation of energy reserves to maintain high survival and potential fecundity.

Journal Article↗
PubMed2000

Relationship of decrease in fecundity with advancing age to structural changes in mouse endometrium.

The aim of this study was to determine whether a relationship exists between decrease in fecundity and structural changes in the antimesometrial endometrium of the mouse. Fecundity was calculated as the number of animals showing a placental sign/number of copulated animals x 100 (%). Structural changes in the endometrium were examined by electron microscopy. A negative correlation between age and fecundity was found. Fecundity was 50% at 7 mo of age. At this age, amorphous material appeared in the region between the basement membrane deep to the luminal epithelium and the subepithelial cells. This material was sometimes attached to the basement membrane. It increased in amount with advancing age, as fecundity decreased. The structure of the uterine luminal epithelial cells did not alter with age. The results indicated that decrease in fecundity with advancing age is correlated with the appearance of amorphous material beneath the basal lamina of the endometrial epithelium. It is suggested that this could impair communication between the luminal epithelium and the endometrial stroma, which plays an important role in implantation.

Aging↗
PubMed1996

Age-specific patterns of genetic variance in Drosophila melanogaster. II. Fecundity and its genetic covariance with age-specific mortality.

Under the mutation accumulation model of senescence, it was predicted that the additive genetic variance (VA) for fitness traits will increase with age. We measured age-specific mortality and fecundity from 65,134 Drosophila melanogaster and estimated genetic variance components, based on reciprocal crosses of extracted second chromosome lines. Elsewhere we report the results for mortality. Here, for fecundity, we report a bimodal pattern for VA with peaks at 3 days and at 17-31 days. Under the antagonistic pleiotropy model of senescence, it was predicted that negative correlations will exist between early and late life history traits. For fecundity itself we find positive genetic correlations among age classes > 3 days but negative nonsignificant correlations between fecundity at 3 days and at older age classes. For fecundity vs. age-specific mortality, we find positive fitness correlations (negative genetic correlations) among the traits at all ages > 3 days but a negative fitness correlation between fecundity at 3 days and mortality at the oldest ages (positive genetic correlations). For age-specific mortality itself we find overwhelmingly positive genetic correlations among all age classes. The data suggest that mutation accumulation may be a major source of standing genetic variance for senescence.

Aging↗
PubMed2002

Laboratory fecundity as predictor of field success in Trichogramma carverae (Hymenoptera: Trichogrammatidae).

Laboratory fecundity assessments are routinely used to determine the quality of commercially reared Trichogramma egg parasitoids before release for pest control, but there is little information on the relevance of this trait to the field success of Trichogramma. Herein, we characterize the parasitism success of strains of Trichogramma carverae Oatman & Pinto in the laboratory on a factitious (Sitotroga cerealella Olivier) and a natural (Epiphyas postvittana Walker) host. Differences in fecundity of the strains in the laboratory were consistent with a heritability of approximately 10%, allowing ranking of the strains from highest to lowest fecundity. The strains with particularly high and low fecundities were tested for successful parasitism in the field. Results of the field releases show that strain differences in laboratory fecundity did not influence field performance. The implications of this result for fecundity as a quality indicator for commercial stocks are discussed.

Animals↗
PubMed2000

Parental consumption of contaminated sport fish from Lake Ontario and predicted fecundability.

Wildlife studies suggest that consumption of contaminated fish from the Great Lakes may expose humans to polychlorinated biphenyls and persistent chlorinated pesticides. To assess whether time to pregnancy or fecundability is affected, we conducted a telephone survey in 1993 with female members of the New York State Angler Cohort Study who were considering pregnancy between 1991 and 1994 (N = 2,445). Among the 1,234 (50%) women who became pregnant, 895 (73%) had a known time to pregnancy. Upon enrollment into the cohort in 1991, both partners reported duration and frequency of Lake Ontario sport fish consumption. We estimated lifetime exposure to polychlorinated biphenyls from recent consumption and used a discrete-time analog of Cox proportional hazards analysis to estimate conditional fecundability ratios and 95% confidence intervals (CIs) for fish consumption among couples with complete exposure data who discontinued birth control to become pregnant (N = 575). Maternal consumption of fish for 3-6 years was associated with reduced fecundability (fecundability ratio = 0.75; 95% CI = 0.59-0.91), as was more than a monthly fish meal in 1991 (fecundability ratio = 0.73; 95% CI = 0.54-0.98). Our findings suggest that maternal but not paternal consumption of contaminated fish may reduce fecundability among couples attempting pregnancy.

Adult↗
PubMed1986

The fecundity of Schistosoma mansoni in chronic nonhuman primate infections and after transplantation into naive hosts.

Adult Schistosoma mansoni worms were transplanted from 8 nonhuman primates with chronic infections into 8 naive recipients, in an effort to test the hypothesis that worm fecundity reduction in chronic infections is the result of host immunity or some other host effect. Techniques for perfusing living donors without the added use of anti-schistosomal drugs and for reducing the likelihood of post-operative bacterial endotoxemia and septic shock are described. Fecundity values in terms of eggs per day per female worm were obtained for the worms in their original and in their new hosts and compared. In 3 experiments, perfusions were incomplete and the donors were saved, enabling direct comparisons of fecundity to be made in subpopulations of worms in both their original and new hosts, after equal life spans. In only 1 of the 8 transplantations was there a clear increase in fecundity after surgical introduction into a naive host. Therefore, these experiments fail to support the hypothesis that reduced fecundity of S. mansoni worms in permissive nonhuman primate hosts is a reversible result of host immunity or some other host-derived factor. Despite this negation, further evidence for reduced worm fecundity in older infections was obtained. In the absence of in vivo evidence for immune-mediated antifecundity, worm senescence is the most likely explanation for this finding, with irreversible immune damage to the worms being a less attractive alternative hypothesis.

Animals↗
PubMed1989

Reduced fecundability in women with prenatal exposure to cigarette smoking.

Animal studies have suggested that fertility may be impaired by transplacental exposures, but little is known about human prenatal exposures and subsequent adult reproduction. A possible relation between prenatal exposure to cigarette smoking and adult fecundability in women was explored, with the use of data from a prospective study of 221 North Carolina couples. These couples were recruited during 1983-1985, at the time they stopped using birth control in order to become pregnant. The relative fecundability of exposed compared with unexposed women was estimated by applying a discrete-time proportional probabilities model to the cycle-by-cycle conception rates. Women with prenatal exposure to their mother's cigarette smoking had reduced fecundability. The fecundability ratio associated with prenatal exposure to mother's smoking, adjusted for age, frequency of intercourse, current smoking status, age at menarche, and childhood exposure to cigarette smoking, was 0.5 (95% confidence interval 0.4-0.8). This association was not changed by further adjustment for other possible confounding variables, including educational level, reproductive history, body weight, and consumption of alcohol and caffeine. Thus, women whose mothers smoked while pregnant with them may be on average substantially less fecund than women whose mothers did not smoke during pregnancy.

Adult↗
PubMed2003

Female fecundity before and after operation for familial adenomatous polyposis.

BACKGROUND: Knowledge about the fertility of women suffering from familial adenomatous polyposis (FAP) is scarce and inconclusive. The purpose of this study was to investigate the fecundity of women with FAP before and after operation, and to compare the findings with those of a general population database and women with ulcerative colitis. METHODS: A questionnaire concerning reproductive experiences and waiting times to pregnancy was sent to all 230 women on the polyposis registers in Denmark, Finland, Sweden and Norway in whom primary surgery had consisted of ileorectal anastomosis or ileal pouch-anal anastomosis. Data on the general population and women with ulcerative colitis came from an existing database. Cox regression and Kaplan-Meier plots were used for analysis. RESULTS: The fecundity of women with FAP before operation and after colectomy with ileorectal anastomosis was similar to that of the general population. However, fecundity dropped to 54 per cent (P = 0.015) following proctocolectomy with ileal pouch-anal anastomosis, although it was greater than the postoperative fecundity of women with ulcerative colitis. CONCLUSION: The significant reduction in female fecundity after ileal pouch-anal anastomosis should be communicated to young women with FAP before it is decided which surgical option to follow.

Adenomatous Polyposis Coli↗
PubMed1991

A study of the mortality and fecundity of Haemonchus contortus in sheep following experimental infections.

The regulation of the fecundity and mortality of H. contortus in sheep was examined using a series of mathematical models. Six-month-old Dorset crossbred lambs were infected once only with various doses of infective H. contortus larvae (500-20,000 larvae). Parasite mortality was found to be an increasing linear function of the magnitude of the initial infection over the range of doses examined. Parasite fecundity was found to remain constant over the intensity and duration of the infection. The average fecundity for H. contortus at the time of slaughter was found to be 7037 eggs per female worm per day. There was no evidence of time-dependent changes in fecundity or density-dependent regulation of fecundity.

Animals↗
PubMed1991

The relationship between intestinal location and fecundity in adult Trichinella spiralis.

Adult female worms recovered from the jejunum of rats infected per os with 1000 larvae of Trichinella spiralis were significantly more fecund (peak jejunal fecundity = 35.7 +/- 3.1 newborn larvae per female) than females recovered from the terminal ileum (9.3 +/- 4.1 larvae per female) in the same infections. The majority of the adult worms were established in those sections of the small intestines that produced the most fecund females (r = 0.92; P less than 0.05). Worm fecundity is believed to be location-specific because adult females that were surgically implanted into the jejunum were significantly more fecund that were implanted into only the ileum. It is concluded that the physico-chemical conditions of the anterior small intestines are optimal for the parasites' reproductive fitness and this exerts a strong selective pressure on habitat selection behavior.

Animals↗
PubMed1991

The regulation of mortality and fecundity in Schistosoma mattheei following a single experimental infection in sheep.

The regulation of mortality and fecundity of Schistosoma mattheei in sheep was examined using a series of mathematical models applied to data culled from the literature. Parasite mortality (mu) was found to be an increasing linear function of the magnitude of the initial infection over the ranges of doses examined (200-91,000 cercariae) where mu = 9.78 x 10(-3) + 3.476 x 10(-7) infection dose. Parasite fecundity (lambda) was found to be inversely related to the duration of the infection. The best fit model for parasite fecundity was one in which fecundity decreased exponentially with time since initial infection, lambda = lambda 0e-delta(t-tau). There was no evidence for density-dependent regulation of fecundity.

Animals↗