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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↗
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↗
PubMed1987

Fecundity and size in the housefly: investigations of some environmental sources and genetic correlates of variation.

Environmental sources and genetic correlates of variation in fecundity and size were studied in field and laboratory housefly populations in central Iowa, U.S.A. Electrophoresis of enzymatic proteins was used to monitor genotypes and heterozygosity. In the field, mean fecundity declined as adult densities increased. Fecundity varied greatly within breeding seasons. Fly body size varied spatially and temporally during summer and winter. Fecundity and size were positively correlated. Size was independent of genotypes at the six loci studied. No relationship was observed between heterozygosity and the magnitude or variability of body size.

Analysis of Variance↗
PubMed1986

Fecundability rates from an infertile male population.

From a computer file of 955 couples attending hospital because of an infertile marriage, 279 were identified where the female partner had normal investigation results. Follow-up information was available for all couples and the fecundability (conception rate per month) for the first year of follow-up has been calculated, stratified according to the husband's investigation results. The fecundability of couples where the wife had normal investigation results but the husband had reduced sperm density ranged from 0.4% for wives with azoospermic husbands to 5.9% when the husband had at least 10 million motile sperm/ml. For any given number of motile sperm the fecundability was also strongly dependent on the duration of involuntary infertility as recorded at the time of initial clinic attendance. In view of the lack of effective treatment for most male infertility the fecundability rates reported herein are likely to represent those that would be found in an untreated population and should be useful as a base line when evaluating results of new treatments.

Female↗
PubMed1981

Social selection in seeking medical care for reduced fecundity among women in Denmark.

This study is based on a representative sample of 709 Danish women aged between 25 and 45 who were interviewed in 1979. The purpose was to estimate the proportion of women with reduced fecundity who seek medical care and to identify sociodemographic variables associated with presentation to the medical care system. The study showed that the majority of women with reduced fecundity did not seek medical care. The propensity to seek care was not significantly associated with a woman's age or education, nor with family income or the employment status of the head of the household. Women living in rural areas or in homes with two or more rooms per family member had a greater tendency to seek medical care for secondary reduced fecundity compared with women living in cities or in more crowded homes. The implications of these findings for epidemiological studies of the association of reduced fecundity and occupation are discussed.

Adult↗
PubMed2002

Complete removal of endometriosis improves fecundity.

Endometriosis is one of the causative factors of impaired fecundity. Whatever the mechanisms are of this impairment, surgical removal of endometriosis appears to increase postoperative fecundity. Our strategy in laparoscopic surgery for symptomatic endometriosis is to completely remove endometriosis. However, despite this strategy, laparoscopic surgery nonetheless creates two categories of patients; complete and incomplete surgery groups. We found by comparing the two groups that both were comparable in terms of fecundity during the early postoperative phase, whereas unlike the complete surgery group, fecundity in the incomplete surgery group stayed low during the late postoperative phase. Deep rectal endometriosis and deeply invading pelvic endometriosis are conditions wherein complete removal of endometriosis is difficult. We have developed laparoscopic surgeries for these conditions: laparoscopic anterior rectum slicing (LARS) and laparoscopic pelvic wall slicing (LPWS) operations, respectively. Both operations are effective in alleviating disease-related symptoms with minimal surgical invasiveness.

Adult↗
PubMed1999

Phenology and fecundity in 11 sympatric pioneer species of Macaranga (Euphorbiaceae)in Borneo.

Reproductive traits of tropical tree species vary predictably in relation to successional stage, but this variation may be due to the species' phylogenetic histories rather than selective pressures imposed by regeneration requirements. Reproductive phenology, tree size at the onset of reproduction, and fecundity of 11 sympatric, closely related Macaranga species were studied to investigate within-species variation in reproductive traits in relation to resource availability, and among-species variation in relation to other life-history traits (shade tolerance, seed size and maximum tree size, H(max)) and consequently the requirements for forest-gap colonization. Nine species reproduced in synchronous episodes, and two species reproduced continuously over 32 mo. Episodic reproduction was most intense in 1992 following a severe drought. For several species, reproductive trees had greater light availability, lower fecundity in lower light levels, and lower growth rates than nonreproductive trees, reflecting resource-limited reproduction. Among species, H(max) was negatively correlated with shade tolerance and seed size. Tree size at the onset of reproduction and fecundity was strongly linked to this axis of life-history variation, but phenological pattern was not. Absolute tree size at the onset of reproduction was positively correlated with H(max) and negatively correlated with shade tolerance. Relative size at reproductive onset was not correlated with shade tolerance or H(max). Fecundity ranged four orders of magnitude among species and was correlated positively with H(max) and negatively with seed size and shade tolerance. The interrelationships among these reproductive and other life-history traits are strongly correlated with the species' requirements for gap colonization.

Journal Article↗
PubMed1975

A method for the estimation of fecundability.

A new method for the estimation of the mean and variance of fecundability is described. The data input required for this procedure is the distribution of the interval from marriage to first birth, or from the resumption of the conception risk after contraction to the subsequent birth. The estimates of the mean and variance of fecundability are obtained by fitting a model to the observed interval distribution. To test the method, it is applied to data from five historical populations. The fecundability means in these populations ranged from 0.18 to 0.31 while the co-efficients of variation all had values near 0.56. A short method for the estimation of the mean of fecundability based on the same model, but not requiring a computer, is also presented.

Abortion, Spontaneous↗
PubMed2002

Fecundity of the Hypostomus affinis (Siluriformes, Loricariidae) in the Lajes Reservoir, Rio de Janeiro, Brazil.

The armored catfish Hypostomus affinis is a widespread Loricariidae fish in the Lajes Reservoir (22 degrees 42'-22 degrees 50' S; 43 degrees 53'-44 degrees 05' W), the largest lentic environment in the Rio de Janeiro State, but little is known about their reproductive biology. One hundred and twenty five females, captured from January 1996 to December 1997, were used to assess ovarian development (29 were used to determine fecundity). The oocyte distribution by size-diameter classes revealed the occurrence of two modes suggesting an asynchronic development of the ovaries. The total fecundity ranged from 1235 to 4304, averaging 2374. An exponential relationship between fecundity and total length was determined, and a direct linear relationship was found between fecundity and total weight and gonad weight.

Animals↗
PubMed1991

Gonadal protection and fecundity rates in cyclophosphamide-treated rats.

Premature ovarian failure and reduced fecundity are well-documented consequences of cytotoxic chemotherapy used to treat patients with malignant diseases. To investigate the ability of different hormonal agents to block the effects of cyclophosphamide (CTX) on reproductive function, sexually mature female Long-Evans rats were studied. Model development demonstrated that CTX, 6 mg/kg/day, 5 days/week for 3 weeks, was successful at inducing acyclicity and significantly reducing fertility and fecundity, with acceptable mortality, when compared to higher/lower dosages. Utilizing this model, animals were treated with CTX in combination with an inert vehicle, Lupron, 80 micrograms/kg every 24 h, Lupron, 40 micrograms/kg every 12 h, or s.c. progesterone capsules obtaining serum progesterone levels of 20-30 ng/ml. We concluded that progesterone was able to protect the gonad from the negative effects of CTX, maintaining fertility and fecundity rates not significantly different from those of untreated control animals. Lupron given every 12 h had a similar effect on fertility, but failed to protect fecundity (P less than 0.001).

Animals↗
PubMed1990

The effect of Schistosoma haematobium infection on the growth and fecundity of three sympatric species of bulinid snails.

Three species of bulinid snails were monitored to determine the effect of infection with 2 sympatric strains of Schistosoma haematobium on longevity, growth, and reproductive output, from the onset of cercarial production until death. Bulinus senegalensis was least affected by infection, with total fecundity reduced by less than 34%. Infected Bulinus truncatus showed an acceleration in growth accompanied by a 63% reduction in fecundity, although the majority of snails continued to oviposit at a low level. The longest-lived snails in this study, Bulinus globosus, showed decreased growth and survival when infected. In addition a significant proportion of infected individuals of this species failed to oviposit, and those that retained some reproductive capacity produced fewer embryos than controls. Total fecundity of B. globosus was reduced almost 90% by infection with S. haematobium, yet long-term monitoring of individuals showed that reproductive activity recovered when parasite productivity was low. Results from this and similar studies indicate that the time of infection by a trematode in relation to reproductive maturity of the molluscan host is important in determining the subsequent effects on host growth and fecundity.

Animals↗
PubMed1994

Is human fecundity declining--and does occupational exposures play a role in such a decline if it exists?

Demographers have analyzed fertility over time and between many populations for many decades. Much less is known about fecundity. Recent publications seem to indicate a decline in semen quality over time, but still no good data corroborate or refute this hypothesis. The very sparse data do not indicate any substantial changes in fecundity over the last 10-30 years in the United States, but none of the studies have a comparability which permit any firm conclusion. Several chemical and physical exposures interfere with human fecundity. Some are found at the worksite, sometimes in an intensity which does harm. The marked effect of dibromochloropropane on semen quality and fecundity was a clear warning to occupational health workers. Several other occupational exposures have shown an effect on gonads in men or women, and it is time to give more research priority to the topic. The rapidly rising cost of infertility treatment could be the stimulus to trigger the development of this research field.

Female↗
PubMed1991

Reporting errors in time-to-pregnancy data collected with a short questionnaire. Impact on power and estimation of fecundability ratios.

Few tools exist in reproductive epidemiology for studying adverse effects on fertility. Data on time to pregnancy (the number of menstrual cycles required to conceive) can be used to estimate fecundability ratios, a sensitive endpoint for identifying factors associated with reduced fertility. Time-to-pregnancy data can be collected in detailed interviews. The accuracy of data collected on brief, self-administered questionnaires is not known. In a study of occupational exposures to dental assistants conducted in 1987-1988, 523 women provided time-to-pregnancy data both on a short, mailed questionnaire and in a detailed telephone interview. The correlation between the two measures was 0.82. Assuming that the detailed data were accurate, reporting errors in data from the short form were distributed nondifferentially with respect to most covariates of interest in fecundability analyses. Simulation studies were conducted to estimate bias and loss of power from the misclassification. Bias was toward the null. Substantial power was lost in detecting weak exposures. However, exposures that reduce fecundability by 50 percent (equivalent to adding about three cycles to the median time to pregnancy) could still be detected with 80 percent power in samples of about 100 women (half of them exposed to a possible toxin). The authors conclude that time-to-pregnancy data collected with a few self-administered questions can be useful in a variety of epidemiologic studies, including occupational and environmental surveillance programs.

Bias↗
PubMed2000

Daily fecundability: first results from a new data base.

This multicenter study has produced a database of 7017 menstrual cycles contributed by 881 women. It provides improved knowledge on length and location of the "fertile window" (identified as of up to 12 days duration) and the patterns and level of daily conception probability. The day of ovulation was identified in each cycle from records of basal body temperature and mucus symptoms. By referencing days of intercourse to the surrogate ovulation markers, estimates of daily fecundability were computed either directly or by the Scwartz model, both for single and multiple acts of intercourse in the fertile window. The relationship between coital pattern and fecundability has been explored. Univariate analysis underlines the significant link with fecundability only of the woman's reproductive history.

Developed Countries↗