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At least 19 recordsLinked to original sources
PubMed1994

The end of fertility: age, fecundity and fecundability in women.

Onset of capacity for childbearing in women is dated biologically by menarche, although actual onset may be delayed. The end of childbearing is less understood but recent demographic and biological research on fertility at older ages in clarifying the end of fertility. The demographic view of declining fertility with age is based on age-specific fertility in natural fertility populations, artificial insemination and pregnancy rates by age and World Fertility Survey data. New data from the Demographic and Health Surveys on exposure to the risk of pregnancy shows that whereas older women biologically need longer exposure to pregnancy, exposure declines on behavioural grounds such as duration of marriage. Actual fecundity is obscured by factors of fecundability. Recent research on medically assisted conception is adding to the understanding of declining fecundity with age, especially the relative contributions of endometrial and ovarian ageing. This paper reviews the available information on declining fertility with age and discusses the implications of the extension of fertility through new medical technologies.

Adult↗
PubMed1988

Effect of chronic protein-energy malnutrition on fecundability, fecundity and fertility in rats.

To assess the effect of chronic protein-energy malnutrition on fecundability (ovulation rate), fecundity (percentage of animals bred that conceived) and fertility (live fetuses at d 18 of pregnancy), 42-d-old female rats were assigned to six groups: two dietary treatment groups and, within each treatment group, three outcome groups. Rats were fed ad libitum (AL) or were chronically restricted (CR) to 50% of AL intake for 28 d before ovulation was assessed and then until implantation and fetal viability were measured. In the ovulation groups, corpora lutea were counted at estrus. In the implantation groups, blastocyst implantation sites were quantified by using Pontamine Blue dye at d 5 of pregnancy. In the viability groups, live and dead fetuses and metrial nodes were counted at d 18 of pregnancy. CR rats had 74% as many corpora lutea as AL rats; however, fecundity did not differ between dietary treatments. CR rats had 71% as many blastocyst implantation sites and 65% as many viable fetuses as AL rats. Chronic malnutrition negatively affected weight gain before and during pregnancy as well as reproductive performance. These findings help to explain why CR rats have fewer progeny.

Animals↗
PubMed1996

Comparison of ovarian follicles (stage, number and estradiol concentration) in high fecundity Olkuska sheep, low fecundity Polish mountain sheep and their crossbreeds.

The objective of this study was to identify whether high ovulation rate in high fecundity Polish Olkuska Sheep results from within ovary differences by comparing the number, size and estradiol concentration in ovarian follicles obtained from high fecundity ewes of Olkuska breed, non prolific Polish Mountain Sheep and the crossbreed between them. The ovaries were obtained after laparotomy from the anesthetized animals on the 17th day after the onset of estrus. The diameter of individual follicles was estimated with the use of operating microscope with a calibrated scale in the ocular. Dissected follicles were stored at -20 °C for the estradiol estimations in the homogenates. The mean number of highly estrogenic and medium follicles in crossbreed was significantly lower than that in Olkuska and significantly higher than that in Polish Mountain. However, mean estradiol level in high estrogenic and medium follicles in three investigated groups was not significantly different. Mean ovulation rates were 3.1 for Olkuska, 1.5 for Polish Mountain and 2.2 for crossbreed. It is concluded that, like in Booroola sheep, the increased number of follicles that mature and ovulate results from the differences within the ovary. The recruitment of ovulatory follicles in high fecundity Olkuska sheep, lasts longer than in non prolific Polish Mountain sheep and similar tendency has been observed in crossbreed.

Journal Article↗
PubMed1999

We should monitor human fecundity, but how? A suggestion for a new method that may also be used to identify determinants of low fecundity.

Human fecundity may be declining, and we may need ways to monitor it. The most simple monitoring is based on measuring waiting time to pregnancy retrospectively among pregnant women. Unfortunately, this design does not provide an estimate of fecundity, because infertile couples are excluded. We suggest a novel approach that combines the measurement of waiting time for pregnant women with information on the distribution of waiting time among women waiting to become pregnant. The method is based on principles from the case-cohort design.

Epidemiologic Methods↗
PubMed1997

Effects of cigarette smoking, caffeine consumption, and alcohol intake on fecundability.

Data from the Ontario Farm Family Health Study were analyzed to determine whether smoking, caffeine, or alcohol use among men and women affect fecundability (the monthly probability of conception). In this retrospective cohort study of farm couples in Ontario, Canada, the farm operator, husband, and wife completed questionnaires during 1991-1992, yielding information on 2,607 planned pregnancies that had occurred over the previous 30 years. Fecundability ratios were calculated using an analog of the Cox proportional hazards model. Cigarette smoking among women and men was associated with decreased fecundability (fecundability ratio = 0.90, 95% confidence interval (CI) 0.82-0.98 and fecundability ratio = 0.88, 95% CI 0.81-0.95, respectively). Caffeine consumption of 100 mg or less versus more than 100 mg in women and men was not associated with fecundability (fecundability ratio = 0.98, 95% CI 0.91-1.07 and fecundability ratio = 1.05, 95% CI 0.97-1.14, respectively). Decreases were observed among women who were coffee drinkers (fecundability ratio = 0.92, 95% CI 0.84-1.00) and men who were heavy tea drinkers (fecundability ratio = 0.85, 95% CI 0.69-1.05), regardless of caffeine content. Alcohol use among women and men was not associated with fecundability. These data are consistent with previous studies of the adverse effect of tobacco on fecundability in female smokers and suggest an effect of smoking among males. Continued evaluation of coffee and tea is warranted to address constituents other than caffeine.

Adult↗
PubMed2003

Reproductive biology of Hemiramphus brasiliensis and H. balao (hemiramphidae): maturation, spawning frequency, and fecundity.

Analyses of life-history data show that both the size-specific batch fecundities and the age-specific spawning frequencies differ for two halfbeak species, Hemiramphus brasiliensis, the ballyhoo, and H. balao, the balao. Halfbeak ages were determined from sectioned otoliths; histological data was used to describe oocyte development and estimate spawning frequency; and batch fecundity was measured from counts of whole oocytes in final maturation. Hemiramphus brasiliensis lived longer (4 versus 2 years) and had a higher survival rate (14.9% versus 7.5% annually) than H. balao did. Of the two species the larger and longer-lived congener, H. brasiliensis, reached sexual maturity at a larger size (fork length 198 versus 160 mm). The spawning period of age-0 females was strongly related to season, whereas spawning by older females occurred throughout the year. Reproduction by both species peaked during late spring or early summer, and all mature females were spawning daily during April (H. brasiliensis) or June (H. balao). This is the first demonstration of iteroparity for the family Hemiramphidae. H. brasiliensis had a lower batch fecundity (about 1164 versus 3743 hydrated oocytes for a 100-g female) than H. balao did. Such low batch fecundities are typical of the order Beloniformes, but quite different from those of other fishes that live in association with coral reef habitats. H. balao's higher batch fecundity is consistent with the life-history theory that predicts higher numbers of eggs for shorter-lived species; this is possible because H. balao produces smaller hydrated oocytes than H. brasiliensis (modal diameter about 1.6 versus 2.4 mm). The high spawning frequency of Hemiramphus species compensates for their low batch fecundity. The annual fecundity of both species is similar to that of other reef fish species, after adjusting for body size and spawning frequency. The lifetime fecundity of H. balao was very similar to that of H. brasiliensis, after accounting for the differences in survival for each species. This suggests a fine tuning of different reproductive traits over the entire life cycle that results in roughly equivalent lifetime fecundity for both species.

Animals↗
PubMed1999

Fecundability trends among sperm donors as a measure of donor performance.

OBJECTIVE: To examine fecundability trends among sperm donors. DESIGN: Retrospective analysis. SETTING: University-based sperm bank and donor insemination program. PATIENT(S): Sperm donors and recipients. INTERVENTION(S): A group of recipients underwent IUI with cryopreserved donor sperm. Fecundability was calculated for 20 sperm donors over 800 insemination cycles. MAIN OUTCOME MEASURE(S): Average fecundability per donor was compared for the first 40 cycles of a donor's use and for those donors within a group of more fertile recipients. Sperm parameters, recipient ages, and number of unique recipients for each donor were analyzed. RESULT(S): Average donor fecundability is constant; however, individual donors demonstrated differences among their fecundabilities (overall mean, 0.09; range, 0.01-0.26). These differences persisted for donors among a group of more fertile recipients (overall mean, 0.12; range, 0.02-0.35). A donor's fecundability at 15 cycles is predictive of his future performance. CONCLUSION(S): Differences in fecundability exist among sperm donors which cannot be discerned through routine semen parameters. Sperm donor fecundability should be analyzed periodically, and directors of sperm banks should consider discontinuing use of a donor whose outcome is substandard.

Fertility↗
PubMed1999

The curvilinear relationship between worm length and fecundity of Teladorsagia circumcincta.

The variation among sheep in fecundity of Teladorsagia (Ostertagia) circumcincta was estimated by dividing the faecal egg count by the worm number following deliberate infection of mature Scottish Blackface lambs. Fecundity was skewed and ranged from 0 to 350 eggs per worm per day. Most animals had relatively low worm fecundities, but a small number of individuals had relatively high worm fecundities. However, as fecundity is a ratio of two imprecise estimates, extreme values may be statistical artefacts. Following both deliberate and natural infection, differences in worm fecundity were associated with differences in adult female worm length. In both infections, fecundity varied with worm length to the power 0.4. This relationship should assist the measurement of fecundity in studies of host immunity, in epidemiological modelling and in estimating the influence of density-dependent relationships.

Animals↗
PubMed1995

Within- and between-generation effects of temperature on early fecundity of Drosophila melanogaster.

We used a repeated-measures, four-factor experimental design to determine how the fecundity of Drosophila melanogaster during the first 5 days of adult life was influenced by paternal, maternal, developmental and laying temperature, with two different temperature levels (18 degrees C vs. 25 degrees C) per factor. Laying temperature had by far the largest effect on fecundity and accounted for 79 per cent of the variance in overall fecundity: flies laying at 25 degrees C began laying eggs about a day earlier and had much higher daily fecundities than did those laying at 18 degrees C. Developmental temperature had no significant effect either on overall fecundity or on the pattern of daily egg production. Dam temperature had a slight effect on the pattern of daily egg production, but not on overall fecundity. In contrast, sire temperature slightly influenced both overall fecundity and the pattern of daily egg production. Our results demonstrate that early fecundity is extraordinarily sensitive to laying temperature (360 per cent increase if laying at 25 degrees C vs. at 18 degrees C), but is relatively well buffered against developmental and cross-generational effects (maximum effect only 7 per cent, for sire temperature).

Animals↗
PubMed1999

Change in sexual size dimorphism as a correlated response to selection on fecundity.

Fecundity selection is often suggested as the main causal factor underlying the prevalence of female-biased sexual size dimorphism (SSD), but this assumption has not been empirically tested. We selected female Drosophila melanogaster for increased or decreased fecundity (eggs laid over a single 18-h period, between days 5 and 7 posteclosion) for 20 generations, to see what effect this would have on SSD in three morphological traits (thorax width, abdomen width and thorax length). A direct response to fecundity selection was found in the downward direction (16.6%), whereas the response to upward selection (5.7%) was not statistically significant. Significant sex by selection interaction terms in the ANOVAs for thorax width and abdomen width indicate that the two sexes responded differently. Females usually showed a greater correlated response than males. In lines selected for increased fecundity, the correlated response in females for thorax and abdomen width was greater than the direct response in standard deviation units. SSD generally increased with selection for increased fecundity, but showed no consistent trend with selection for decreased fecundity. These results support the general hypothesis that SSD can evolve rapidly in response to fecundity selection. Selection on fecundity also produced correlated responses in life history traits. Downward selection resulted in flies that had lower viability and longevity, and both directions of selection were associated with an increase in development time.

Animals↗
PubMed2000

Comorbid fibromyalgia accounts for reduced fecundity in women with myofascial face pain.

OBJECTIVE: This study examined factors related to reduced fecundity among women with myofascial face pain (MFP) arising from hypotheses concerning the role of neurohormonal factors in MFP and associated conditions. DESIGN: Fecundity rates among 162 MFP cases and 173 demographically equivalent acquaintance female controls were compared. OUTCOME MEASURES: Fecundity indicators and factors underlying differential fecundity rates were investigated. RESULTS: It was determined that female cases with MFP had significantly fewer children and were more likely to have never been pregnant. Although women with MFP were more likely than controls to indicate that volitional factors related to their health discouraged them from any or additional pregnancies, these factors did not account for lower rates of fecundity. MFP cases also did not differ from controls on self-reported indicators of infertility. Moreover, we show that reduced fecundity was restricted to the subgroup of MFP cases who reported a history of fibromyalgia. CONCLUSIONS: Reduced fecundity in women with MFP is restricted to those who self-report a history of fibromyalgia. Possible mechanisms for reduced fecundity in fibromyalgia are discussed. These findings highlight the need to screen for widespread pain among women with regional myofascial pain syndromes.

Adolescent↗
PubMed2002

Fecundity of the freshwater fish Channa punctatus (Bloch) from three aquatic bodies.

The fecundity studies on Channa punctatus revealed that there is a relationship between length of the fish with fecundity, weight of the fish and ovary with fecundity. The length and fecundity exhibit curvilinear relationship and a straight line relationship is observed between fecundity and body weight. Fecundity and ovary weight also exhibited linear relationship. The comparative degree of fecundity of the fish is Jagat tank > Kadaganchi tank > Kagina river. Although fish collected from Jagat tank exhibits higher fecundity, all the other three aquatic bodies provide proper environmental conditions for the growth and reproductive activity of the fish.

Animals↗
PubMed1989

The relationship of sperm parameters to cycle fecundity in superovulated women undergoing intrauterine insemination.

Semen parameters of raw and prepared (post-swim-up) specimens from 451 cycles of intrauterine insemination (IUI) were analyzed in relation to cycle fecundity in 232 patients undergoing ovarian stimulation with sequential clomiphene citrate/menotropin therapy. Pregnancy occurred in 42 cycles, resulting in an overall pregnancy rate of 17.7%, and a cycle fecundity of 9.3%. Cycle fecundity was positively correlated with the parameters of post-swim-up log sperm density (r = 0.994), and with log total motile sperm inseminated (r = 0.964; inseminates were limited to a maximum of 20 million total motile sperm). Post-swim-up motility did not correlate (r = 0.308) with cycle fecundity; however, most specimens had a motility of greater than 40% post-swim-up. Only one pregnancy occurred when less than 1 million motile sperm were inseminated (38 cycles), which resulted in a cycle fecundity of 2.6% for these cycles. This may represent the threshold of effectiveness for IUI in this setting. Highest cycle fecundity was obtained with an inseminate containing approximately 10 million or more motile sperm. Parameters of raw samples correlated less well with cycle fecundity than did prepared specimens. Analysis of post-swim-up semen parameters can provide useful prognostic information for women undergoing IUI with ovarian stimulation; this information is helpful in counseling patients regarding their chances of success with this therapy.

Adult↗
PubMed1998

Fecundity of infertile women with minimal or mild endometriosis and women with unexplained infertility. The Canadian Collaborative Group on Endometriosis.

OBJECTIVE: To assess whether infertile women with minimal or mild endometriosis have lower fecundity than women with unexplained infertility. DESIGN: Prospective cohort study. SETTING: Twenty-three infertility clinics across Canada. PATIENT(S): Three hundred thirty-one infertile women aged 20-39 years. INTERVENTION(S): Diagnostic laparoscopy for infertility. Infertile women with minimal or mild endometriosis (n = 168) were compared with women with unexplained infertility (n = 263). Both groups were managed expectantly. The women were followed up for 36 weeks after the laparoscopy or, for those who became pregnant, for up to 20 weeks of the pregnancy. MAIN OUTCOME MEASURE(S): Fecundity refers to the probability of becoming pregnant in the first 36 weeks after laparoscopy and carrying the pregnancy for > or = 20 weeks. The fecundity rate is the number of pregnancies per 100 person-months. RESULT(S): Fecundity was 18.2% in infertile women with minimal or mild endometriosis and 23.7% in women without endometriosis (log-rank test). The fecundity rate was 2.52 per 100 person-months in women with endometriosis and 3.48 per 100 person-months in women with unexplained infertility. The crude and adjusted fecundity rate ratios were 0.72 and 0.83 (95% confidence interval = 0.53-1.32), respectively. CONCLUSION(S): The fecundity of infertile women with minimal or mild endometriosis is not significantly lower than that of women with unexplained infertility.

Adult↗
PubMed2002

Fecundity and life-history strategies in marine invertebrates.

The reproductive strategies of an organism play a major role in the dynamics of the population and the biogeography and continuity of the species. Numerous processes are involved in reproduction leading to the production of offspring. Although diverse processes are involved in oogenesis (the production of eggs) and spermatogenesis (the production of sperm), the basic patterns of gametogenesis are similar amongst invertebrates, with the proliferation and differentiation of germ cells leading to the final production of mature gametes. The production of gametes, especially eggs, is energetically expensive, and therefore strongly sensitive to selective pressures. An organism can ingest and assimilate a limited amount of energy from the environment. The different ways by which energy is allocated to growth and reproduction in order to maximize fitness forms the basis of the differing life-history strategies that have developed in marine invertebrates. Fecundity is defined as the number of offspring produced by a female in a determined time period. The term fecundity needs to be explicitly defined in each study in order to obtain the maximum information from the data analysed. Because of the variety of egg production patterns found among marine invertebrates, a wide range of methodologies has been developed to quantify fecundity. These include direct egg counts in brooding species, spawning induction in live individuals and histological studies of preserved material. Specific considerations need to be taken into account for colonial organisms, because of their modular organization. The production of eggs requires an optimal allocation of energy into growth and reproduction for the maximization of parental fitness. Fecundity is central in studies of life-history theory and in the development of life-history models because it is directly related to energy allocation and partitioning. There are important relationships and trade-offs between fecundity and other life-history traits, such as egg size, female size and age, age at first reproduction, reproductive effort and residual reproductive value. These trade-offs, together with morpho-functional constraints and genetic variation determine the evolution of life histories through natural selection. Fecundity is a highly plastic character within the limits defined by the bioenergetics and life-history strategy of the organism. Egg production is affected mainly by environmental factors such as food quantity and quality, temperature or presence of toxic elements in the habitat. The differences in fecundity found among closely related species from different biogeographical locations reflect, at least in part, the differing environmental conditions of their habitat.

Adaptation, Physiological↗
PubMed2002

Ulcerative colitis: female fecundity before diagnosis, during disease, and after surgery compared with a population sample.

BACKGROUND & AIMS: Women with ulcerative colitis generally have normal fertility. The aim of this study was to compare patients' fecundability before and after restorative proctocolectomy with ileal pouch-anal anastomosis with the fecundability of the general population. METHODS: Historical follow-up was performed on 343 consecutive female patients aged 10.6-40.5 years at surgery and a reference population of 1200 women aged 25-40 years. A total of 290 (85%) patients and 661 (55%) women in the reference population agreed to participate in a structured telephone interview concerning reproductive behavior and waiting times to pregnancy. Cox regression and Kaplan-Meier plots were used for analysis. RESULTS: Surgery significantly reduced the ratio of patient to reference population fecundability, which decreased to 0.20 (P < 0.0001). Before diagnosis and from diagnosis until colectomy, the fecundability of the patients was similar to that of the reference population. CONCLUSIONS: Female patients with ulcerative colitis have normal fecundity before surgical treatment. Surgery severely reduces female fecundity. Information about this reduction in fecundity should be given before surgery, and if a woman has an unfulfilled wish for pregnancy after surgery, early referral to a gynecologist is recommended.

Adult↗