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PubMed1998

Fecundity in Thai and European regions: results based on waiting time to pregnancy.

Very little is known about the frequency of subfecundity in different cultures, ethnic groups and regions. To fill this gap, the European Study Group on Infertility and Subfecundity established data on the prevalence of infertility and subfecundity in five European regions. In this study, a comparison of fecundity was made between 4035 Caucasian women from five European countries and 1496 Asian women from southern Thailand. Fecundity was measured using 'time to pregnancy', i.e. the time women took to conceive after stopping contraceptive methods. The Thai primigravid women had a shorter time to pregnancy than European women, whereas time to pregnancy was found to be longer among Thai multigravidae, although this was not statistically significant. This study has illustrated that cross-culture comparison of subfecundity is difficult despite using a common protocol and questionnaire because of differences in the use of contraceptive methods and a different concept of pregnancy planning. The distribution of time to pregnancy for the Thai women was not outside the variation found within the European samples.

Adult↗
PubMed2004

Assisted reproduction may change birth intentions.

OBJECTIVE: To determine whether the development and expansion of assisted reproductive technology (ART) between 1982 and 1995 raised the birth intentions of subfecund people relative to fecund people. DESIGN: Comparison of birth intention rates among fecund and subfecund women in the 1982, 1988, and 1995 rounds of the National Survey of Family Growth, standardized by age, parity, and education. SETTING: No clinical setting. PARTICIPANT(S): Nationally representative samples of married women who were 20 to 44 years old. INTERVENTION(S): None. RESULT(S): Between 1982 and 1995, birth intentions rose at least 2.5 times faster among subfecund women than among fecund women. This rise was not due to increasing average age at maternity over the period. CONCLUSION(S): The development of ART and expansion of services may well have increased birth intentions among subfecund women between 1982 and 1995.

Adult↗
PubMed1999

Fecundity in the modern city: a comparison of couples attending antenatal clinics in Manchester (UK) and Melbourne (Australia).

To determine the characteristics of couples with resolved subfecundity and to compare these findings in two geographically distant centres, a self-reporting questionnaire was completed by a sample of women attending six antenatal clinics in Greater Manchester, UK and five antenatal clinics in Melbourne, Australia. A total of 2158 pregnant women, 1106 from Manchester and 1052 from Melbourne participated in the study. The prevalence of subfecundity (proportion of women who failed to conceive current pregnancy within 12 months of unprotected intercourse) and demographic and medical factors potentially related to subfecundity were measured. The samples from the two cities had similar medical characteristics, but several socioeconomic and cultural differences were detected. Characteristics which independently correlated with decreased fecundity were increasing parental age, previous pregnancy, previous miscarriage, maternal smoking before conception and low socioeconomic status. Increased body mass index was also a significant, independent predictor of decreased fecundity, but in the Melbourne sample only. Subfecundity was found to be influenced by a combination of parental and socioeconomic factors as well as previous pregnancy. The factors identified were similar in two modern industrial societies in very different geographical locations, only their relative importance differing between Australia and the UK.

Journal Article↗
PubMed2004

Is previous aberrant reproductive outcome predictive of subsequently reduced fecundity?

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

Abortion, Induced↗
PubMed1983

Tobacco use, alcohol consumption and infertility.

An epidemiological study of the association between alcohol consumption, tobacco use and subfecundity is presented. Study subjects were recruited for a case-control study whose primary objective was to examine the association between occupational exposures and subfecundity. All 1069 women treated for infertility at Odense University Hospital during the period 1977-1980 were eligible for participation as cases. A control group was chosen consisting of 4305 women who had each delivered a healthy child with a gestational age over 258 days at the same hospital in the period 1977-1979. Data regarding occupational exposures and smoking and drinking habits were collected by mailed questionnaires. A response rate of 87% was obtained for both case and control groups. Use of tobacco and alcohol was significantly higher in cases compared to controls. A within-group comparison of alcohol consumption among controls with delayed conception of more than one year with controls who conceived their children within one year failed to demonstrate a statistical association. However, a statistically significant association was observed between smoking and delayed conception among controls. On the basis of this finding, along with further analyses, the authors suggest that the statistical association between smoking and subfecundity may be real and ought to be studied further. Moderate alcohol consumption does not seem to play a role in the development of subfecundity. The paper provides a systematic review of possible sources of bias in the study.

Alcohol Drinking↗
PubMed1979

Frustrated fertility: a population paradox.

This Bulletin examines the causes of subfecundity -- the diminished ability to reproduce -- and its effect today and in the past on the fertility, or actual reproductive performance, of individuals and, hence, populations. By definition, all real populations are subfecund since all experience some degree of involuntary biological factors affecting coitus, conception, or the ability to carry a conceptus to live birth which reduces their fecundity below the estimated biological population maximum of 15 children per woman. Affecting both men and women, these factors fall into 5 categories: genetic factors such as blood group incompatibilities and inherited sickle cell anemia or diabetes; psychopathology, including psychic stress and behavioral disorders (e.g., drug and alcohol abuse); infectious diseases such as gonorrhea, malaria, tuberculosis, and postabortion infection; malnutrrition, including the chronic undernutrition of the 3rd World and the overnutrition of developed societies; and hazards posed by increasing amounts of radiation and toxic chemicals in the environment. Reducing subfecundity requires improved living conditions, avoidance of or protection from known hazards, and adoption of medical advances which now can help 40 to 60% of subfecund couples. But even in the U.S. fertility would certainly rise among the 15% of couples now estimated to be involuntarily childless and the 10% who have fewer children than they want, and among disadvantaged groups, and teenagers.

Abortion, Induced↗
PubMed2004

Negative lifestyle is associated with a significant reduction in fecundity.

OBJECTIVE: To evaluate the association patterns and quantify the effects of lifestyle on time to pregnancy (TTP). DESIGN: Observational study. SETTING: Teaching hospitals in Hull, United Kingdom. PATIENT(S): Two thousand and one hundred twelve consecutive pregnant women. INTERVENTION(S): A questionnaire inquiring about TTP, contraceptive use, pregnancy planning, previous subfertility/pregnancies, age, and lifestyle characteristics of either partner. MAIN OUTCOME MEASURE(S): We compared TTP, conception rates, and relative risk of subfecundity between subgroups with different lifestyle characteristics. RESULT(S): We found that TTP was significantly longer if the woman or partner smoked >15 cigarettes/day (P<.001 and.04, respectively), the partner consumed >20 alcohol units/week (P<.001), the woman's body mass index was >25 kg/m(2) (P<.001), their coffee and/or tea intake was >6 cups/day (P=.04), or if they were socially deprived (P<.001). Each of these effects remained unchanged after adjusting for the potential confounders. The relative-risks of subfecundity with each of these variables ranged between 1.4 to 1.9 (1.4 to 3.6 after adjustment). The effects of coital frequency and recreational drug use were insignificant. Couples who had >4 negative lifestyle variables had a sevenfold longer TTP; their conception probabilities fell by 60%, and they were 7.3-fold more likely to be subfecund than those without negative variables. CONCLUSION(S): Lifestyle has a significant and cumulative impact on fecundity. Dose-dependent effects occur with smoking, alcohol, and tea/coffee consumption. Appropriate counseling could result in substantial reductions in the referrals for fertility investigations and treatments.

Attitude to Health↗
PubMed1997

Is fecundability associated with month of birth? An analysis of 19th and early 20th century family reconstitution data from The Netherlands.

The relationship between fecundability and month of birth was investigated in a cohort of 1526 women who married between 1802 and 1929, using only women whose first marriage occurred before the age of 35 years. On the basis of their time to pregnancy (TTP, calculated as time between wedding and first birth minus gestational length), women were categorized into two groups: fecunds (TTP up to 12 months or prenuptial conceptions, n = 1348) and subfecunds (TTP >18 months, n = 118). By use of logistic regression, cosinor functions with a period of 1 year or 6 months and variable shift and amplitude were fitted through the monthly odds of subfecunds versus fecunds. The best fitting curve was unimodal, with a zenith in September (P = 0.13 for H0: no differences). Exclusion of childless women (n = 36, minimum follow-up 5 years) from the subfecunds led to a similar curve (P < 0.01), while childless women, as compared with fecunds, showed a birth distribution that was best represented with a bimodal curve with zeniths in January and July (P = 0.06). This study provides evidence for the existence of differences in fecundability by month of birth. The cause of this relationship is unclear, but may lie in a melatonin-dependent circannual variability of the quality of the oocyte.

Female↗
PubMed2000

Time to pregnancy as a correlate of fecundity: differential persistence in trying to become pregnant as a source of bias.

BACKGROUND: Subfecundity is a frequent and often serious problem and it is important to identify its preventable determinants and to monitor fecundity over time. Since follow-up studies are difficult and expensive to conduct, time to pregnancy (TTP) in pregnant women is often used as a surrogate measure of fecundity. TTP data can be retrieved at low costs and they need no valid population registry as a source for sampling. While TTP may serve as a valid surrogate measure in many situations, its validity rests upon a number of assumptions. We have analysed one of these overlooked assumptions, the importance of persistence in trying to become pregnant. METHODS: By means of computer simulations we estimated bias caused by differences in persistence in pregnancy attempts. We investigated whether the assumptions made in the simulation were realistic by using empirical data from a European study. RESULTS: The mean waiting time to pregnancy and other estimates of subfecundity (or infertility) strongly depend upon the persistence of couples in pursuing a pregnancy. We show that even moderate changes in the planning behaviour considerably modify the waiting time distribution. Empirical data confirm that persistence in trying to become pregnant is age-related. CONCLUSIONS: Persistence in pregnancy attempts affects outcome measures of subfecundity in studies based upon TTP in pregnant women. It is likely that the length of time during which couples keep trying to become pregnant is influenced by a number of factors which would probably change over time or be different between populations to be compared.

Adult↗
PubMed2001

Moderate alcohol consumption and waiting time to pregnancy.

BACKGROUND: Recent research indicates that even a moderate consumption of alcohol in women trying to become pregnant is associated with longer waiting time to pregnancy. The findings, though, are based upon few observations. METHODS: Self-reported data on alcohol intake and waiting time to pregnancy (0-2, 3-5, 6-12 and >12 months) was used for 39 612 pregnant women, recruited to the Danish National Birth Cohort within the first 24 weeks of pregnancy from 1997 to 2000. Main outcome measures were odds ratios (OR) for a prolonged waiting time to pregnancy according to alcohol intake. RESULTS: In nulliparous women neither moderate nor high alcohol intake was related with longer waiting time to pregnancy compared with a low intake. In parous women, a modest association was seen only among those with an intake of >14 drinks per week (subfecundity OR 1.3; 95% confidence interval 1.0-1.7). Women who reported no alcohol intake had a slightly longer waiting time (subfecundity OR 1.2; 95% confidence interval 1.1-1.3) than women with a moderate intake of alcohol. CONCLUSIONS: Our findings do not corroborate recent results suggesting a marked reduction in fecundity associated with a moderate intake of alcohol.

Adult↗
PubMed2004

Is previous use of hormonal contraception associated with a detrimental effect on subsequent fecundity?

BACKGROUND: The effects of contraception on subsequent fecundity are yet to be substantiated. METHODS: A total of 2841 consecutive pregnant women in Hull and Sheffield completed questionnaires inquiring about time to pregnancy (TTP), contraceptive use, pregnancy planning, previous pregnancies, age and lifestyle characteristics of each partner. Outcome measures were mean TTP, conception probability and odds of subfecundity after discontinuing each contraceptive method. RESULTS: TTP following long-term combined oral contraceptive (COC), short-term intrauterine device (IUD) or any duration of injectable use were 2.0-, 1.6-, 3.0-fold longer than TTP after condom use, respectively. Within 6 months of discontinuing COC or injectable use, conception probabilities were 0.86 and 0.34, respectively, whereas those relevant to other methods were not significantly different. All levonorgestrel intrauterine system (IUS) users conceived within 1 month. Relative to condoms, odds of subfecundity after COC, injectable and short-term IUD use were 1.9, 5.5, 2.9, respectively. The effect of COC and injectables was stronger with long-term use, in older, obese or oligomenorrhoeic women. Similar results were obtained after adjustment for potential confounders. CONCLUSIONS: A significant reduction in fecundity occurs after COC, IUD or injectables, which is dependent on the duration of use. The effect of COC and injectables is evident in women with a potentially compromised ovarian function. Use of progesterone-only pills or IUS is not associated with a significant effect.

Condoms↗
PubMed1990

Pathophysiology of mild endometriosis: review of literature.

Endometriosis is a puzzling condition and the literature is characterized by a large number of uncontrolled reports on its aetiology and pathophysiology. In particular the relationship between mild endometriosis and subfecundity is uncertain. This paper critically reviews the published literature on the pathogenesis, prevalence, menstrual symptomatology and natural history of endometriosis. Furthermore, factors implicated in causing subfecundity in relation to endometriosis and the impact of various treatments in enhancing fertility among women with mild endometriosis have been assessed.

Ascitic Fluid↗
PubMed2005

How effective is assisted reproduction technology? A model assessment.

BACKGROUND: All conceptions occurring after a treatment for infertility are usually attributed to the treatment. This is only true when only totally sterile couples are treated: subfecund couples may still conceive without treatment. METHODS: We used a computer simulation (Monte Carlo) model of reproduction, combining the monthly probability of conceiving, the risk of miscarriage and the probability of age dependent permanent sterility. After a delay (D) without conceiving, the couples are assumed to turn to assisted reproduction technology. The treatment increases the fecundability (monthly rate of conception) of subfecund couples and restores the fertility of some totally sterile couples. The overall effectiveness of the therapy is based on data (by age of women) for two attempts of IVF. The number of conceptions ending in a live birth with ART is compared to the number of conceptions after one or two additional years without ART. RESULTS: At 30 years of age, the crude effectiveness of ART, based on all conceptions after treatment, is double that observed without treatment (30% vs. 15%), and beyond 41 years of age, the number of conceptions with treatment is no higher than without treatment over two years of exposure to conception (15% for both at 41 years of age, 7% at 45 years of age). Shortening the delay (D) does not improve the total number of women conceiving and having a live birth unless we assume the couple try again to spontaneously conceive. CONCLUSIONS: The chances of conceiving spontaneously must not be ignored when defining an infertility treatment, especially in cases of unexplained infertility. Shortening the delay before using ART is not in itself a more efficient strategy.

Computer Simulation↗
PubMed2001

Effects of male age on semen quality and fertility: a review of the literature.

OBJECTIVE: To review the literature on the association between male age and semen quality (semen volume, concentration, motility, and morphology) and fertility status (pregnancy rate and time to pregnancy/subfecundity). METHOD(S): Review of English language-published research over the last 20 years from January 1, 1980, through December 31, 1999, using MEDLINE and Biosis databases. Studies with insufficient numbers of subjects, case reports, case series, or anecdotal data were excluded. RESULT(S): Among the methodologically stronger studies, decreases in semen volume of 3%-22%, decreases in sperm motility of 3%-37%, and decreases in percent normal sperm of 4%-18% were likely when comparing 30-year-old men to 50-year-old men. Most studies examining fertility status suggest a relationship between male age and fertility, but the results are most likely confounded by female partner age. Among studies that did control for female age, comparisons between men under 30 and men over 50 found relative decreases in pregnancy rates between 23% and 38%. A comparison of the various age categories showed that the increased risks for subfecundity ranged from 11% to 250%. CONCLUSION(S): The weight of the evidence suggests that increased male age is associated with a decline in semen volume, sperm motility, and sperm morphology but not with sperm concentration.

Adult↗
PubMed2003

Effect of male age on fertility: evidence for the decline in male fertility with increasing age.

OBJECTIVE: To evaluate the effect of men's age on time to pregnancy (TTP) using age at the onset of pregnancy attempts, adjusting for the confounding effects of women's age, coital frequency, and life-style characteristics. DESIGN: Observational study. SETTINGS: Teaching hospital in Hull, United Kingdom. PATIENT(S): Two thousand one hundred twelve consecutive pregnant women. INTERVENTION(S): A questionnaire inquiring about TTP, contraceptive use, pregnancy planning, previous subfertility, previous pregnancies, age, and individual life-style characteristics of both partners. MAIN OUTCOME MEASURE(S): Time to pregnancy, conception rates, and relative risk of subfecundity for men and women's age groups. RESULTS: As with women's age, increasing men's age was associated with significantly rising TTP and declining conception rates. A fivefold increase in TTP occurred with men's age >45 years. Relative to men <25 years old, those >45 years were 4.6-fold and 12.5-fold more likely to have had TTP of >1 or >2 years. Restricting the analysis to partners of young women revealed similar effects of increasing men's age. Women >35 years were 2.2-fold more likely to be subfertile than women <25 years. The results were comparable, whether age at conception or at the onset of pregnancy attempts was analyzed, and they remained unchanged after adjustment for the confounding factors. CONCLUSION(S): Evidence for and quantification of the decline in men's fertility with increasing age is provided.

Adult↗
PubMed1998

Environmental toxicants and female reproduction.

OBJECTIVE: To review current knowledge on the potential effects of environmental toxicants on female reproduction in laboratory animals, wildlife, and humans. DESIGN: Published literature about the effects of endocrine disruptors, heavy metals, solvents, pesticides, plastics, industrial chemicals, and cigarette smoke on female reproduction. RESULT(S): Published data indicate that chemical exposures may cause alterations in reproductive behavior and contribute to subfecundity, infertility, pregnancy loss, growth retardation, intrauterine fetal demise, birth defect, and ovarian failure in laboratory animals and wildlife. Data on the association of chemical exposures and adverse reproductive outcomes in humans are equivocal and often controversial. Some studies indicate that chemical exposures are associated with infertility, spontaneous abortion, or reproductive cancer in women. In contrast, other studies indicate that there is no association between chemical exposures and adverse reproductive outcomes. The reasons for ambiguous findings in human studies are unknown but likely include the fact that many studies are limited by multiple confounders, inadequate methodology, inappropriate endpoints, and small sample size. The mechanism by which chemicals alter reproductive function in all species is complex and may involve hormonal and/or immune disruption, DNA adduct formation, altered cellular proliferation, or inappropriate cellular death. CONCLUSION(S): Studies are needed to clarify which toxicants affect human reproduction and by which mechanisms of action. Furthermore, methods should be developed to minimize exposure to known reproductive toxicants such as dioxins and cigarette smoke.

Environmental Exposure↗
PubMed1999

Cigarette smoking and effects on menstrual function.

OBJECTIVE: To examine the relationship between smoking and menstrual function, using biologic measures rather than self-report of menstrual cycle characteristics. METHODS: In a prospective study, 408 women collected urine daily for one to seven menstrual segments (cycles), maintained daily diaries, and completed detailed interviews. Smoking data from the diaries were averaged over each segment and verified by cotinine assay. Urine samples were analyzed for metabolites of steroid hormones to define the day of ovulation and various menstrual characteristics, including: 1) segment, follicular, luteal phase, and menses length, 2) variability, and 3) anovulation. RESULTS: Heavy smoking (at least 20 cigarettes per day) was associated with nearly four times the risk of short segment (less than 25 days) as was nonsmoking (adjusted odds ratio 3.8, 95% confidence limits 1.1, 12.7). Mean segment length was on average 2.6 days shorter with heavy versus no smoking (95% confidence limits 0.14, 5.0), due almost entirely to shortening of the follicular phase. Women who smoked an average of ten or more cigarettes per day had significantly more variable segment and menses lengths than nonsmokers. Based on small numbers, the data suggested that with greater smoking, there was a possible increased risk of anovulation and short luteal phase. Segments of exsmokers with ten or more pack-years of exposure were more likely to be short and have shorter luteal phases than those of never smokers. CONCLUSION: The effects found in this study of smoking on the menstrual cycle might explain in part associations of smoking with other reproductive endpoints, such as subfecundity and early menopause.

Adolescent↗
PubMed1999

Contraceptive effectiveness of two spermicides: a randomized trial.

OBJECTIVE: We conducted a multinational randomized trial to determine whether a spermicidal film containing 72 mg of nonoxynol-9 per film was at least as effective in preventing pregnancy as a foaming tablet containing 100 mg of nonoxynol-9 per tablet. METHODS: Between September 1995 and July 1997, 765 women aged 18-35 years who had no evidence of subfecundity were randomly assigned to use one of the two spermicides as their only contraceptive method at every coital act for 28 weeks. Participants were asked to keep coital diaries throughout the study period. Pregnancy tests were performed on a scheduled basis. Each participant was followed for 28 weeks or until she stopped considering the spermicide as her primary method of contraception. RESULTS: The Kaplan-Meier estimate of the 6-month probability of pregnancy during typical use of the spermicide was 28.0% in the tablet group and 24.9% in the film group (P = .78, one-tailed test). The study had nearly 75% power to have detected a difference of seven percentage points between groups. Results were almost identical when the analysis included only months when the participants reported use of the spermicide during every coital act. Reported levels of sexual activity and compliance with use of the spermicide were high in both groups. CONCLUSION: The contraceptive effectiveness of these two spermicidal products appeared similar. Both products were associated with a fairly high risk of pregnancy in this young, highly sexually active population.

Adolescent↗