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PubMed2001

The effects of female age on fecundity and pregnancy outcome.

In industrialized countries worldwide, women are delaying childbearing for a variety of reasons, including pursuit of career, greater financial independence, improved and more accessible contraception and longer life expectancy. In terms of fertility and maternity, those aged > or = 35 years are considered to be of advanced maternal age and there are usually marked reductions in both the fecundity rate for spontaneous conceptions and the success rates with assisted conception. These decreases are thought to be due mainly to oocyte ageing, and the established success of oocyte donation from younger individuals to older recipients supports this contention. For those who achieve a pregnancy at an advanced maternal age there is a greater likelihood of aneuploidy (assuming conception with the woman's own oocytes), hypertensive and other medical disorders, birth by Caesarean section and maternal mortality. However, most of the complications associated with advanced maternal age are caused by age-related confounding variables, and older premenopausal women in good health should not require special attention. The data on perinatal mortality rates are encouraging and in the absence of congenital abnormalities perinatal mortality is probably not much increased, if at all, in older mothers. Pregnancy is now possible for postmenopausal women with the application of oocyte donation, but these individuals have a significantly higher likelihood of cardiovascular ageing and should be considered at increased risk of vascular complications during pregnancy.

Adult↗
PubMed1999

Prediction of fecundability from semen analysis: problems in providing an accurate prognosis.

Information from semen analysis is used to predict the likelihood that a couple will conceive within a period of time. It is only possible to provide a probability; there can be no certainty. The probability is influenced by a host of factors including semen quality, and studies in large groups or using simple models are required to overcome this. Delayed conception from natural intercourse or poor fertilization at IVF has limited predictive power for a subsequent attempt. The problem is made worse by variations in sperm parameters among different ejaculates from the same man and by differences among groups of patients. Results of studies of potential criteria should be presented in a way that allows the effect of the test result on the probability of conception to be appreciated, and results should be confirmed on independent data sets. When there is potential for fertility, estimation of fecundability can only be approximate; however, progress is possible. Effects of semen quality can be clearly identified in large groups, and computer assisted semen analysis measurements do provide useful additional information for the success of intracervical insemination.

Journal Article↗
PubMedDate not supplied

Fecundity of daughters born after short, intermediate, or long birth intervals. An analysis of family reconstitutions from The Netherlands, late 19th-early 20th century.

In an historical cohort study, we compared the reproductive performances of women born after short (< 14 completed months), intermediate (21-32 completed months), and long (> 39 completed months) birth intervals. Of the initial study base, comprising family reconstitutions of 1,425 women born between 1873 and 1902 in or around Rotterdam (The Netherlands) and married before age 45, a large portion (data of 1,001 women born between 1888 and 1902) was uninformative because of (unintended) selection on birth control behavior. Among the remaining 424 women, those born after very short birth intervals (less than 1 year) showed higher likelihood of childlessness and stillbirth in the offspring than those born after intermediate intervals (adjusted odds ratios (OR) and 95%-confidence intervals: 7.7 [1.8-33.0] and 3.3 [1.3-8.3], respectively). The latter association, however, nearly disappeared after restriction to women whose preceding sibling lived at least 1 year. Women born after modestly short intervals (12-13 months) exhibited longer interpregnancy intervals. So did women born after long birth intervals, but this might well be attributable to intergenerational transmission of reproductive behavior. These results indicate that fecundability is reduced in women born after short birth intervals.

Adult↗
PubMedDate not supplied

Gestation, thermoregulation, and metabolism in a viviparous snake, Vipera aspis: evidence for fecundity-independent costs.

Oxygen consumption of gestating Aspic vipers, Vipera aspis (L.), was strongly dependent on body temperature and mass. Temperature-controlled, mass-independent oxygen consumption did not differ between pregnant and nonpregnant females. Maternal metabolism was not influenced during early gestation by the number of embryos carried but was weakly influenced during late gestation. These results differ from previous investigations that show an increase in mass-independent oxygen consumption in reproductive females relative to nonreproductive females and a positive relationship between metabolism and litter size. These data also conflict with published field data on V. aspis that show a strong metabolic cost associated with reproduction. We propose that, under controlled conditions (i.e., females exposed to precise ambient temperatures), following the mobilisation of resources to create follicles (i.e., vitellogenesis), early gestation per se may not be an energetically expensive period in reproduction. However, under natural conditions, the metabolic rate of reproductive females is strongly increased by a shift in thermal ecology (higher body temperature and longer basking periods), enabling pregnant females to accelerate the process of gestation. Combining both laboratory and field investigation in a viviparous snake, we suggest that reproduction entails discrete changes in the thermal ecology of females to provide optimal temperatures to the embryos, whatever their number. This results in the counterintuitive notion that metabolism may well be largely independent of fecundity during gestation, at least in an ectothermic reptile.

Animals↗
PubMed2005

Amino acids in nectar enhance butterfly fecundity: a long-awaited link.

Thirty years ago, researchers discovered that flowers pollinated by butterflies are consistently rich in nectar amino acids, and more recent findings have shown that butterflies prefer nectar with high amino acid content. These observations led to speculation that amino acids in nectar enhance butterfly fitness and that butterflies have acted as agents of natural selection on nectar composition. Despite a number of experimental efforts over the years, convincing proof that nectar amino acids affect butterfly fitness has been lacking. Here, we provide the first evidence that amino acids in nectar have a positive effect on fecundity of one butterfly species, supporting the existence of a relationship between nectar preferences and fitness benefits. Map butterflies (Araschnia levana L.) raised under natural larval food conditions laid more eggs when they were fed nectar containing amino acids, whereas nectar amino acids had no effect on the number of eggs laid by butterflies raised on larval food rich in nitrogen. Uptake and utilization of nectar amino acids by map butterflies appear to be compensatory mechanisms enabling them to override impacts of poor larval food. These results provide strong support for the long-standing postulate that nectar amino acids benefit butterflies.

Amino Acids↗
PubMed2003

Invited commentary: the potential for monitoring of fecundity and the remaining challenges.

In the epidemiologic study of reproductive capacity, the assessment of fecundity as a functional measure is complementary to approaches that focus on biomedical mechanisms and/or that use biomarkers such as semen quality. More research is needed on time trends, spatial patterns, and particular groups, especially those exposed to potentially toxic agents. Although specific research projects will always be important, much could be gained by general population surveillance, which could be introduced into existing multipurpose surveys and repeated periodically. The core measurement would be time to pregnancy, which can be carried out using a short, acceptable questionnaire that has good validity at the group level. This should be accompanied by questions on time periods of unprotected intercourse that do not end with conception, to avoid bias resulting from exclusion of relatively infertile couples. Information is also required on contraceptive failures, recent contraceptive use, and other covariates and possibly on behavioral variables, such as the degree of planning and persistence in trying to conceive, and couples' knowledge of fertile days of the menstrual cycle. Existing statistical methods can deal with possible biases due to "accidental" pregnancies and the effects of fertility treatment. Further methodological work is needed to avoid or measure more subtle biases, for example, to determine the best way to deal with pregnancies occurring to couples whose approach to family formation is relaxed, for whom the concept of "pregnancy planning" does not apply.

Female↗
PubMed1996

L-deprenyl treatment in aged mice slightly increases life spans, and greatly reduces fecundity by aged males.

Male and female B6D2F1 (C57BL/6J x DBA/2J)F1 and B6CBAF1 (C57BL/6J x CBA/CaHT6J)F1 mice were injected subcutaneously 3 times a week with L-deprenyl (0.25 mg/kg) starting at mean ages of 26 months and 18.5 months, respectively. Life spans of aging mice were increased 6-9% by the drug. While none of the life span effects were significant for a single genotype and gender, life spans were significantly longer in L-deprenyl-treated animals (p = .011) when all data were combined. L-deprenyl-injected mice consumed about the same amounts of food as controls: L-deprenyl 3.1 g/day, control 3.3 g/day, after 7 months of treatment. There were no significant effects of L-deprenyl on measures of changes with age in the following biological systems: activity, excitement, red blood cell mass, collagen denaturation rate, and wound healing rate. L-deprenyl-treated B6CBAF1 males and females were significantly heavier than controls after 4-6 months of treatment. To measure fecundity, B6CBAF1 males at an average age of 750 days were each caged with two young B6 females; 10 of 17 L-deprenyl-injected males sired an average of 31.3 pups per male, while 14 of 24 controls sired 82.1 pups per male.

Aging↗
PubMed2000

Ovulation side and cycle fecundity: a retrospective analysis of frozen/thawed embryo transfer cycles.

The aim of the study was to evaluate a possible lateral difference in ovarian activity and its effect on cycle fecundity. A database was analysed retrospectively which covered 477 cycles in which frozen/thawed embryo transfer had been carried out. The cycles were spontaneous, with no hormonal treatment. Women with ovulation problems as a reason for infertility treatment were excluded. Factors investigated were the side of ovulation, endometrial thickness on cycle days 10-12 and on the day of embryo transfer, and pregnancy rate per embryo transfer. Ovulation was right-sided in 273 of the 477 cycles (57.2%) and left-sided in 204 of the cycles (42. 8%) (95% CI 38.3-47.2, P = 0.002). In the age category of 30-37 years, covering 288 cycles, the incidence of left-sided ovulation was 126 (43.7%, 95% CI 38.0-49.5, P = 0.034). In this category, the endometrial thickness (+/-SD) was significantly greater on the day of embryo transfer (i.e. at time of implantation) when there had been left-sided ovulation compared with right-sided [9.6 mm (2.0) versus 9.1 mm (1.8), P = 0.037]. In addition, the pregnancy rate per embryo transfer was higher when ovulation had been on the left side [32/126 (25.2%) versus right side 24/162 (14.8%), P = 0.035, 95% CI 0.0122-0.199]. In conclusion, right-sided ovulation was more frequent than left-sided in the whole group. This is the first study to report that the side of ovulation has a clinical impact. These data support the hypothesis that the side of ovulation is significant in terms of embryo implantation.

Adult↗
PubMed2000

Increasing paternal age is associated with delayed conception in a large population of fertile couples: evidence for declining fecundity in older men. The ALSPAC Study Team (Avon Longitudinal Study of Pregnancy and Childhood).

The impact of male age on fecundity remains controversial. Here, a large population study was used to investigate the effect of paternal age on time to conception. All couples in the Avon Health district expecting a baby between 1 April 1991 and 31 December 1992 were eligible. Questionnaires completed by both the man and the woman at 18 weeks gestation covered specific fertility factors, e.g. parity, paternity, cohabitation and oral contraception; and non-specific factors, e.g. educational achievement, housing, cigarette smoking, alcohol consumption, obesity. Logistic regression was used to identify factors independently related to conception in < or =6 or < or =12 months. Of 8515 planned pregnancies, 74% were conceived in < or =6 months, 14% in the second 6 months and 12% after more than a year. Nine variables, including the age of the woman, were independently related to time to conception. After adjustment for these, the likelihood of conception within 6 or 12 months was lower in older men. Compared to men <25 years old, the adjusted odds ratios (95% confidence interval) for conception in < or =12 months were 0.62 (0.40, 0.98), 0.50 (0.31, 0.81) and 0.51 (0.31, 0.86) in men aged 30-34, 35-39 and > or =40 years respectively.

Adult↗
PubMed2004

Influence of cotton fruit stages as food sources on boll weevil (Coleoptera: Curculionidae) fecundity and oviposition.

Boll weevil, Anthonomus grandis grandis Boheman (Coloeoptera: Curculionidae), populations in the Lower Rio Grande Valley of Texas increase strongly during the squaring stage, and preemptive insecticide sprays at the pinhead square stage were designed to capitalize on that association. Laboratory assays showed that cotton plant volatiles, or leaves as a food source, do not elicit egg production in wild weevils. Boll weevils fed on large (5.5-8-mm diameter) squares for 7 d resulted in > or = 3.8-fold more gravid females that developed 4.8-fold more chorionated eggs per female than weevils fed on match-head-sized squares, or postbloom, young (5-10-d-old), or old (3-5-wk-old) bolls. When presented with a choice, nongravid females preferred to feed on young and old bolls 4.7- and 8.4-fold more, respectively, than on large squares. In the field, large squares had 7.8- and 25-fold more feeding punctures than match-head-sized squares and bolls, respectively. Oviposition increased > or = 2.7-fold when females fed on large squares compared with match-head-sized squares and bolls. Greater feeding on large squares during squaring and the associated greater fecundity explain rapid weevil population buildups shortly after large squares become well established.

Animals↗
PubMed1990

Fecundity, metabolism, and body size in Anopheles (Diptera: Culicidae), vectors of malaria.

In four Anopheles species, An. albimanus, An. gambiae, An. stephensi, and An. quadrimaculatus Say, total protein, lipid, and carbohydrate present at eclosion, after feeding on sucrose, and after extreme starvation were quantified to study the effect of teneral and maximal reserves on subsequent fecundity and to judge the extent of reserve mobilization and the minimal irreducible amounts required for survival. All parameters were regressed on body size, presented as the cubic value of wing length. Teneral reserves were isometric with body size, were considerably lower than previously reported for Aedes aegypti (L.) and were sexually dimorphic with respect to reserves and body size, all being slightly reduced in males. On the average, up to 70% of the teneral female lipids and up to 50% of their teneral protein could be mobilized during nutritive stress. Conversely, access to sucrose for a few days led to a pronounced glycogenesis (up to 509%) and lipogenesis (up to 450% of the teneral values), depending on the species. In absolute terms, lipogenesis prevailed over glycogenesis. On a caloric basis, up to 30% of the blood meal protein was utilized for synthesis of yolk protein and lipid, and another 15% was deposited as an extra-ovarian, maternal protein and lipid store, perhaps compensating for the limited teneral reserves. A complete nitrogen budget revealed that in a given class of body size, roughly 80% of the blood meal protein was catabolized and excreted through the three major pathways of uricotely, ureotely, and ammonotely. Quantification of the hematin in fecal samples allowed a stoichiometrical determination of the amount of blood ingested. Eco-physiological aspects of larval feeding, teneral reserves, blood meal utilization, and possible behavioral adaptations to these physiological constraints are discussed and compared with previous data on culicine mosquitoes, stressing the invalidity of generalizations among these taxa.

Animals↗
PubMed1993

Effects of temperature on fecundity and viral replication in Amblyomma cajennense (Arachnida: Ixodidae) infected with Venezuelan equine encephalomyelitis virus.

To assess how temperature affects fecundity and Venezuelan equine encephalomyelitis (VEE) viral replication in VEE-infected Amblyomma cajennense (F.), adult ticks were inoculated intracoelomically with either VEE virus (I-A variant) or diluent. Ticks were held at 19, 26, or 33 degrees C and tested for VEE virus over 20 d. Up to 10 pairs of ticks (1 female:1 male) from each temperature group were allowed to feed on guinea pigs on day 8 after inoculation. Maximum titers did not differ significantly among infected ticks held at 19, 26, or 330 degrees C (P = 0.59), and ticks maintained high viral titers throughout the sampling period. Likewise, there was no significant difference in the number of eggs oviposited between ticks inoculated with virus or diluent and held at the same temperature, or among groups held at different temperatures (P = 0.48). The percentage of viable eggs from virus-inoculated or diluent-inoculated adults also was not significantly different (P > or = 0.14).

Animals↗
PubMed1994

Fecundity and proportions of gravid females in populations of the bluetongue vector Culicoides imicola (Diptera: Ceratopogonidae) and several other species in Israel.

The gravid proportions of five Culicoides spp. in Israel were determined based on a suction light trap placed above calves in a cowshed and on two similar traps hung in a Eucalyptus tree at elevations of 1.4 and 26 m. In the cowshed, the proportion of gravid Culicoides distinctipennis Austen showed no significant variation between seasons; C. imicola Kieffer (the dominant species) was caught in significantly smaller proportions in winter; C. schultzei gp (second most dominant) showed no significant seasonal variation. In the Eucalyptus tree, a significantly smaller percentage was gravid in winter at the lower trap, but at the higher trap there was no significant variation between seasons. Culicoides circumscriptus Kieffer showed no significant seasonal variation at either height. C. distinctipennis was present with a significantly higher proportion gravid at the lower level in spring, but no significant variation between seasons was observed in the higher level trap. In C. imicola, gravids were proportionately more numerous in the lower trap in summer and autumn, but, in the higher trap, there was no significant variation between seasons. A significantly greater proportion of gravid C. schultzei gp females occurred at the higher level trap in spring, whereas no significant variation occurred in the lower level trap. Counts of eggs were made for C. cataneii, C. circumscriptus, C. distinctipennis, C. imicola, C. newsteadi Austen, C. obsoletus Meigen, C. saevanicus Dzhafarov, C. schultzei gp, and C. univittatus Vimmer. Counts for all four seasons were made only for C. circumscriptus and C. imicola, and only C. imicola showed significant variation between seasons (fecundity lower in autmn and winter).

Analysis of Variance↗
PubMed1996

Development and fecundity of Dermatophagoides farinae (Acari: Pyroglyphidae).

Duration of the life cycle at 16, 23, 30, and 35 degrees C and fecundity at 23 degrees C and 75% RH were determined for the American house dust mite, Dermatophagoides farinae Hughes. Lengths of the life cycles at 23 and 30 degrees C were 35.6 +/- 4.4 and 17.5 +/- 1.2 d, respectively. Few eggs completed development to the adult stage at 16 and 35 degrees C. At 23 degrees C and 75% RH, the preoviposition period was 3.7 +/- 1.1 d following emergence of the female from the tritonymph. The average reproductive period was 34.0 +/- 10.7 d with a mean total of 65.5 +/- 17.4 eggs produced per female. Female longevity after cessation of egg production was 63.3 +/- 64.6 d.

Animals↗
PubMed1998

Survival, fecundity, and development of Dermatophagoides farinae (Acari: Pyroglyphidae) at fluctuating relative humidity.

We determined the survival, development, and fecundity of Dermatophagoides farinae Hughes exposed to fluctuating daily regimes of hydrating and dehydrating relative humidity. Larva emerged from 84, 92, and 94% of eggs incubated at a regime of 2, 4, and 8 h at 75% RH and 22, 20, and 16 h at 0% RH, respectively. No emerging offspring completed the life cycle when exposed to the 2 and 4 h of moist air daily but 44 and 53% survived for 70 d in the larval or nymphal stages, respectivley, and these completed development to adults when subsequently held at a constant 75% RH. Given 8 h of moist air daily, 41% of emerging offspring completed the life cycle but development was 1.6 times longer compared with development at a constant 75% RH. For all daily hydrating and dehydrating regimes, a greater percentage of offspring became males than females. Overall, survival of immatures was remarkable at these daily long periods of dehydrating conditions when a short period of hydrating moisture was provided. When exposed to a daily regime of 4 h of moist air (75% RH) and 20 h of dry air (0% RH), 84% of females survived 28 d and produced approximately 1/3 of the number of eggs produced at constant 75% RH (control).

Animals↗
PubMed1999

Emergence, survival, and fecundity of adult cat fleas (Siphonaptera: Pulicidae) exposed as pupae to juvenile hormone mimics.

Cat flea, Ctenocephalides felis felis (Bouché), adults exposed to sprays of methoprene, pyriproxyfen, or fenoxycarb as cocooned pupae emerged approximately 1 d earlier than adults from water-treated control pupae. Mortality of adult fleas, after exposure to juvenile hormone mimics as pupae, was increased over that of controls. Females had higher mortality than males within the first 48 h of feeding. Fecundity of females exposed as pupae to juvenile hormone mimics was not different from that of controls. Early emergence of preemerged adults from treated cocoons is discussed along with reasons for higher female susceptibility to juvenile hormone mimics.

Animals↗
PubMed2005

Fecundity of naturally blood-fed Ochlerotatus japonicus.

Ochlerotatus japonicus (Theobald) collected in gravid traps were held individually in modified BioQuip breeders in a darkened room under ambient conditions and readily oviposited on Styrofoam blocks. Counts were made of eggs laid on Styrofoam blocks, container sides, and water surface, and dissections allowed for counts of retained eggs to determine the fecundity of this species. In total, 32,970 eggs were oviposited by 289 females with a range of 3-249 eggs per female. The mean +/- SD number of eggs oviposited per female, 114.08 +/- 51.08, was significantly less than the mean number of eggs produced per female, 125.85 +/- 47.89. Wing lengths ranged from 2.8 to 4.7 mm with a mean of 3.81 +/- 0.38 mm. Wing length was positively correlated with total eggs formed (r2 = 0.3481); wing = 3.22054 + 0.0047 total eggs formed. There was no monthly size difference although females collected during October produced significantly fewer eggs than females collected from June to September. A low egg viability of 40% was attributed to improper storage of the Styrofoam blocks on which eggs were oviposited.

Animals↗
PubMed2004

Fecundity and twinning rates as measures of fertility before diagnosis of germ-cell testicular cancer.

Previous studies have suggested an association between subfertility and testicular cancer by using fecundity and semen characteristics to measure fertility. The occurrence of twinning in offspring may be used to investigate male reproductive health, because dizygotic twinning is reduced by male subfertility. We therefore assessed number of children and offspring twinning rates among 4592 Swedish patients with testicular cancer and 12 254 control subjects. Before diagnosis, case patients had a decreased number of children (for testicular cancer, odds ratio [OR] = 0.71, 95% confidence interval [CI] = 0.62 to 0.81; at least three children compared with no children), with a lower frequency of dizygotic twinning (for unlike-sex twins, OR for the father having testicular cancer = 0.49, 95% CI = 0.22 to 1.08). The ratio of unlike-sex to same-sex twins was 0.22 among children of case patients and 0.66 among children of control subjects (adjusted P =.03, two-sided Wald test). We also found an increased occurrence of twinning after diagnosis, probably attributable to treatment for iatrogenic subfertility. Our study strongly supports evidence of an association between subfertility and the subsequent risk for testicular cancer.

Adult↗