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PubMed1996

Shift work and subfecundity: a European multicenter study. European Study Group on Infertility and Subfecundity.

Shift work has been associated with various unfavorable pregnancy outcomes (ie, pregnancy loss, spontaneous abortion, low birth weight, etc). The suggested underlying mechanism is the interference of shift work with the circadian regulation of human metabolism and, in particular, with the temporal pattern of endocrine function. To analyze the effect of shift work on fecundity, the Time of Unprotected Intercourses (TUI) has been measured in couples recruited in the European Studies on Infertility and Subfecundity, which were undertaken in seven European countries. A low (odds ratio < 2.0) but consistent excess risk of subfecundity (TUI > or = 9.4 months) has been observed both in a representative sample of the general population of women in reproductive age and in a sample of pregnant women or women who had just given birth. The excess risk was also consistently evident both in the subsample of the first pregnancies and in the subsample of the most recent pregnancies. Only the exposure of women to shift work seemed to affect a couple's fecundity; men working shift work did not modify the fecundity pattern of their own couples. No specific job title among shift workers concentrated the risk of subfecundity. No association of menstrual disorders with shift work was identified. Even though residual confounding could partly account for the results and the fact that a plausible biological explanation of the claimed effect is still lacking, data from this study are in favor of an association between shift work and prolonged waiting time to pregnancy.

Adult↗

PubMed1997

Caffeine intake and delayed conception: a European multicenter study on infertility and subfecundity. European Study Group on Infertility Subfecundity.

The effects of caffeine consumption on delayed conception were evaluated in a European multicenter study on risk factors of infertility. Information was collected retrospectively on time of unprotected intercourse for the first pregnancy and the most recent waiting time episode in a randomly selected sample of 3,187 women aged 25-44 years from five European countries (Denmark, Germany, Italy, Poland, and Spain) between August 1991 and February 1993. The consumption of caffeinated beverages at the beginning of the waiting time was used to estimate daily caffeine intake, which was categorized as 0-100, 101-300, 301-500, and > or = 501 mg. Risk of subfecundity (> or = 9.5 months) and the fecundability ratio, respectively, were assessed by logistic regression and Cox proportional hazard analyses, adjusting for age, parity, smoking, alcohol consumption, frequency of intercourse, educational level, working status, use of oral contraceptives, and country. A significantly increased odds ratio (OR) of 1.45 (95% confidence interval (CI) 1.03-2.04) for subfecundity in the first pregnancy was observed for women drinking more than 500 mg of caffeine per day, the effect being relatively stronger in smokers (OR = 1.56, 95% CI 0.92-2.63) than in nonsmokers (OR = 1.38, 95% CI 0.85-2.23). Women in the highest level of consumption had an increase in the time leading to the first pregnancy of 11% (hazard ratio = 0.90, 95% CI 0.78-1.03). These associations were observed consistently in all countries as well as for the most recent waiting time episode. The authors conclude that high levels of caffeine intake may delay conception among fertile women.

Adult↗

PubMed1996

Smoking reduces fecundity: a European multicenter study on infertility and subfecundity. The European Study Group on Infertility and Subfecundity.

Several studies published within the past 10 years indicate that smoking reduces fecundity, but not all studies have found this effect, and smoking cessation is not used routinely in infertility treatment in Europe. The present study was designed to examine male and female smoking at the start of a couple's waiting time to a planned pregnancy. Two types of samples were used: population-based samples of women aged 25-44 years who were randomly selected in different countries from census registers and electoral rolls, in which the unit of analysis was the couple; and pregnancy-based samples of pregnant women (at least 20 weeks' pregnant) who were consecutively recruited during prenatal care visits, in which the unit of analysis was a pregnancy. More than 4,000 couples were included in each sample, and 10 different regions in Europe took part in data collection. The data were collected between August 1991 and February 1993 by personal interview in all population-based samples and in all but three regions of the pregnancy sample, where self-administered questionnaires were used. The results based on the population sample showed a remarkably coherent association between female smoking and subfecundity in each individual country and in all countries together, both with the first pregnancy (odds ratio (OR) = 1.7, 95% confidence interval (CI) 1.3-2.1, at the upper level of exposure) and during the most recent waiting time to pregnancy (OR = 1.6, 95% CI 1.3-2.1). Results based on the pregnancy sample were similar (OR = 1.7, 95% CI 1.3-2.3). No significant association was found with male smoking (in the population sample, OR = 0.9, 95% CI 0.7-1.1 (first pregnancy) and OR = 1.0, 95% CI 0.9-1.3 (most recent waiting time); in the pregnancy sample, OR = 0.9, 95% CI 0.7-1.1). The fecundity distribution among smokers appeared to be shifted toward longer waiting times without a change in the shape of the distribution. Women who have difficulty conceiving should try to stop smoking or to reduce their smoking to less than 10 cigarettes per day.

Adult↗

PubMed1997

Does moderate alcohol intake reduce fecundability? A European multicenter study on infertility and subfecundity. European Study Group on Infertility and Subfecundity.

BACKGROUND AND AIM: There are plausible reasons to suggest that heavy alcohol consumption reduces male as well as female fecundability, but only a few epidemiological studies have addressed this issue, and results concerning the effect of a moderate intake are equivocal. The present studies were designed to examine the association between male and female alcohol intake at the start of the waiting time to a planned pregnancy. METHODS: Two types of studies were used-a population-based study of randomly selected women between 25 and 44 years in the different European countries from census registers and electoral rolls, and a pregnancy-based study of consecutive pregnant women (at least 20 weeks pregnant) recruited during prenatal care encounters. More than 4000 couples were included in each study, and 10 different regions in Europe took part in the data collection. Data were collected through personal interviews in all population-based samples and in all but four regions of the pregnancy study. RESULTS: The results showed no strong nor coherent association between alcohol intake and subfecundity. CONCLUSIONS: Should any causal effect be present it is restricted to females with a high intake of alcohol within the range of normal consumption reported in European countries.

Adult↗

PubMed1982

Prevalence and socioeconomic correlates of subfecundity and spontaneous abortion in Denmark.

This paper provides an estimate of the prevalence of subfecundity and spontaneous abortion in Denmark, and examines social factors associated with these problems of reproduction. The data of this study were collected by interviewing a stratified random sample of 1.4 women per thousand in Denmark between the ages 25 and 45. The interview generated detailed information on reproductive history and sociodemographic data for 709 women. The survey results indicate that reduced fecundity is a relatively common health problem. The proportion of women that either could not achieve a wanted conception or experienced a delay of one or more years before achieving conception was 0.16 in a first pregnancy and 0.17 in a second or subsequent pregnancy attempt. Four per cent of the women interviewed never produced a desired first child and an additional four per cent reported failure to produce a second or subsequent desired child. Social factors relating to subfecundity and spontaneous abortion were studied using logistic regression. No significant associations were found between the occurrence of subfecundity and family net income, employment status of the 'head of the household', area of residence, type of housing or age at time of interview. Women without a college education were more likely to exhibit primary subfecundity than college-educated women (p less than .05). The rate of spontaneous abortion was not found to be associated with socioeconomic class. A significantly higher rate of abortion was found among women with a history of subfecundity than among women with no such history.

Abortion, Incomplete↗

PubMed1998

Are long working hours and shiftwork risk factors for subfecundity? A study among couples from southern Thailand.

OBJECTIVE: To estimate the effect of long working hours and shift work on time to pregnancy. METHODS: Cross sectional samples with retrospective data collection from two 700 bed hospitals at secondary to tertiary care level in Hatyai district, Songkhla Province, Thailand. The study was conducted from March 1995 to November 1995 among 1496 pregnant women attending the antenatal clinics. Subfecundity was defined as time to pregnancy longer than 7.8, 9.5, or 12 months (time to pregnancy was calculated from the date at which the couples started having sexual relations without any contraception until last menstrual date). RESULTS: The descriptive analyses were restricted to 1201 planned pregnancies and the analytical part to 907 working women. Separate analyses on primigravid women were also done. Logistic regressions adjusted for age, education, body mass index, menstrual regularity, obstetric and medical history, coital frequency, and potential exposure to reproductive toxic agents, showed an odds ratio (OR) associated with female exposure to long working hours of 2.3 (95% confidence interval (95% CI) 1.0 to 5.1) in primigravid and 1.6 (1.0 to 2.7) in all pregnant women. Male exposure to long working hours and shiftwork showed no association with subfecundity. The OR of subfecundity was highest when both partners worked > 70 hours a week irrespective of the cut off point used (OR 4.1 (95% CI 1.3 to 13.4) in primigravid women; OR 2.0 (95% CI 1.1 to 3.8) in all pregnant women). CONCLUSIONS: Long working hours is a risk factor for subfecundity especially for women. Shiftwork was not associated with subfecundity in this study.

Adolescent↗

PubMed1997

[Smoking reduces the biological capacity of conception. Results from a European multicenter study. The European Study Group on Infertility and Subfecundity].

The aim of the study was to examine the impact on subfecundity of male and female smoking at the start of a couple's waiting time to a planned pregnancy. Two types of designs were applied: a population based sample of women aged 25-44 years of age and a consecutive sample of pregnant women. Both studies were conducted within well-defined geographical regions in a number of European countries and data were collected by personal interviews in the population-based sample and by interview or self-administered questionnaires in the pregnancy study. A total of 10,665 couples participated in the study. Data on possible risk factors for infertility and subfecundity were collected at the start of the pregnancy planning, and fecundity was estimated by using time from the beginning of unprotected intercourse to a pregnancy, which survived at least 20 gestational weeks. Only couples who planned a pregnancy were included in the analyses. The results showed remarkably coherent associations between female smoking and subfecundity in each individual country and in all countries put together. In the population sample the odds ratio for subfecundity in the first pregnancy was 1.7 (95% c.l. 1.3-2.1 at the upper level of tobacco consumption) and during the most recent waiting time to pregnancy the odds ratio was 1.6 (95% c.l. 1.3-2.1). Results based on the pregnancy sample were similar with an odds ratio of 1.7 (95% c.l. 1.3-2.3). No significant association was found between male smoking and the couple's fecundity.

Adult↗

PubMed2003

Subfecundity and anxiety in a nationally representative sample.

Research thus far on the psychological consequences of impaired fecundity in developed countries has relied heavily on clinic-based samples. This study uses a nationally representative sample of American women regardless of fecundity status or treatment status. I analyze reports of fecundity status and anxiety from a 1995 sample of almost 11,000 respondents. The results show consistent positive effects of subfecundity on the odds of fulfilling the diagnostic criteria for Generalized Anxiety Disorder and the incidence rate of symptoms among those who would be so diagnosed, even when controlling for potential confounding factors. Whether a subfecund respondent currently desires to have a child does not moderate the likelihood of being anxious, but does moderate the number of symptoms reported. The lack of a moderating effect of seeking treatment suggests that past research on clinic-based samples is generalizable to all subfecund women.

Adult↗

PubMed1991

Cigarette smoking, tea and coffee drinking, and subfecundity.

A population-based survey of life-style factors and subfecundity (prolonged time to pregnancy) was conducted between 1984 and 1987 in two cities in Denmark. Altogether, 11,888 women filled out a questionnaire in the last trimester of pregnancy (an 86 percent response rate). After exclusion of women who had been treated for infertility or who did not respond to the question on infertility, 10,886 subjects remained. Among nonsmokers, no association was found between subfecundity (defined as a waiting time of 1 year or more from cessation of contraception to achievement of pregnancy) and consumption of hot caffeinated beverages. For women who smoked and also consumed at least 8 cups of coffee per day (or an equivalent amount of tea), a statistically significant association was seen (odds ratio = 1.35, 95% confidence interval 1.02-1.48) for a wait of 1 year or more. Consumption of coffee was closely related to smoking habits and to a number of social factors, such as education and peer group acceptance, which may play a role in subfecundity.

Adult↗

PubMed1995

Are seasonal preferences in pregnancy planning a source of bias in studies of seasonal variation in reproductive outcomes? The European Study Group on Infertility and Subfecundity.

Seasonal variation in reproductive failures is expected, as many of the putative causes change over the seasons. Many studies have documented such seasonal variation in reproductive failures, but none has addressed the potential source of bias related to seasonal planning of pregnancies. Our aim was to quantify this bias under realistic assumptions. We used data from the European Study of Infertility and Subfecundity, which is a study based upon representative samples of women age 25-44 years in different parts of Europe. Data on pregnancy planning stem from personal interviews. Altogether, we analyzed 4,731 pregnancies. Results show that pregnancy planning is not evenly distributed over the seasons, with summer the preferred time for starting pregnancy. The most fecund will conceive within the preferred time, but those who are subfecund may not succeed until later. Since subfecund women have a higher risk of some reproductive failures (spontaneous abortions, for example), the seasonal planning differences could in themselves lead to seasonal variations in reproductive failures. A simulation model shows that bias related to differential pregnancy planning is likely to have only a small impact under the present conditions in Europe.

Abortion, Spontaneous↗

PubMed2003

Subfecundity as a correlate of preeclampsia: a study within the Danish National Birth Cohort.

A long interpregnancy interval is associated with preeclampsia. If some women experiencing a long interval between births had difficulty conceiving, subfecundity and preeclampsia may share a common etiology. Therefore, the authors examined the association between subfecundity and preeclampsia. By using interview data collected during the second trimester of pregnancy (1998-2001) from women participating in the Danish National Birth Cohort, they identified 20,034 and 24,698 singleton livebirths to primiparous and multiparous women, respectively, for whom preeclampsia information was available from hospital birth records. Among women with no known hypertension, the authors estimated a higher risk of preeclampsia in those with longer times to pregnancy (TTPs), after adjustment for maternal age, prepregnancy body mass index, and smoking. Compared with primiparas who became pregnant right away (referent category), the risk of preeclampsia increased with TTP and then stabilized for women taking 6 months or longer to conceive, whose risk of preeclampsia increased by 50%. Multiparas also had an increased risk, but only those reporting a TTP longer than 12 months (odds ratio = 2.47, 95% confidence interval: 1.30, 4.69). The authors found that a long TTP was associated with preeclampsia, supporting the hypothesis that some factors delaying clinically recognized conception may also be in a causal pathway for preeclampsia.

Adult↗

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↗

PubMed2005

Using infertile patients in epidemiologic studies on subfecundity and embryonal loss.

Subfecundity is a frequent and serious problem that may sometimes be preventable, but we need to know more about its determinants. Different epidemiologic designs are available. The best of these use prospectively collected data from the population, but they are time consuming, expensive and often hampered by low-participation rates. Most patients undergoing infertility treatment are closely monitored for clinical reasons, making it feasible to use secondary data to study the period from conception to implantation and pregnancy. In spite that infertility patients are highly selected, there are specific exposure-effect relations that can be studied in cohorts of infertility patients. These patients offer a potentially useful setting for studying exposures that operate late in fertilization, whereas the designs may be inadequate to identify exposures that cause reduced sperm counts, anovulation and total occlusion. The clinical sampling and the treatment set limitations for what can be studied. In certain situations, infertile patients can, however, provide useful epidemiologic evidence for learning about the causes of subfecundity.

Abortion, Spontaneous↗

PubMed1990

Subfecundity according to the age of the mother and the father.

Time to pregnancy according to the age of the father and the mother has been studied among 10,886 couples from Odense and Aalborg. Late in their pregnancy (36th week) all woman in the two cities were given a questionnaire on time to pregnancy as well as a number of other items. Eighty-six percent responded to this questionnaire, and data concerning previous pregnancies, the outcome of the pregnancy in question, etc., were later collected from medical files. The study showed a strong correlation between mother's age and subfecundity, even after adjustment for a number of potential confounders. The association between subfecundity and the age of the father was much weaker and did not reach statistical significance. Interpretations and implications of these findings are discussed in the paper.

Adolescent↗

PubMedDate not supplied

Adaptation to pregnancy and motherhood among subfecund and fecund primiparous women.

OBJECTIVE: To examine the effects of infertility treatment on women's ability to adapt to pregnancy and motherhood. METHODS: Fecund (n = 261) and subfecund (n = 103) primiparous women receiving obstetrical care in southeastern Michigan participated in this descriptive, correlational, prospective study. The subjects completed Lederman's Pre-Natal Self-Evaluation questionnaire during the third trimester of pregnancy and Lederman's Postpartum Self-Evaluation questionnaire during the first postpartum appointment. FINDINGS: Mean scores showed that the two groups of women were not significantly different with either adaptation to pregnancy or motherhood. CONCLUSIONS & IMPLICATIONS FOR NURSING: Although subfecund women may experience stress in order to achieve a pregnancy, there do not appear to be any latent effects of this stress on their ability to adapt to pregnancy or motherhood.

Adaptation, Psychological↗

PubMed1990

Subfecundity: a prenatal risk factor for adults but not for adolescents.

Young maternal age is associated with an increased incidence of low birth weight and prematurity; controlling for sociodemographic factors reduces the significance of this relationship. We hypothesized that this is partly because in a sociodemographically homogeneous population the adverse effects of maternal subfecundity on fetal growth confound the relationship between maternal age and infant outcome. To test this hypothesis, we studied the reproductive histories of 90 adolescent (less than 20 years old) and 35 adult lower socioeconomic, black prenatal patients. We found a strong, positive relationship between maternal age at conception and duration of unprotected intercourse prior to conception (r = 0.40; p less than 0.0001). Adults reporting 2 or more years of unprotected intercourse prior to conception were at highest risk for low birth weight (p = 0.02). Our findings demonstrate that it is important that adult controls for adolescent pregnancy studies have voluntarily postponed conception.

Adolescent↗

PubMed1993

Discrimination between two competing hypotheses on seasonality of birth in subfecundability traits.

In order to explain the winter (and often summer) birth excess of women characterized by subfecundity two competing hypotheses have been proposed: i) the seasonal preovulatory overripeness ovopathy (SPrOO) hypothesis (1-3) and ii) the epidemic seasonal infertility factors (ESIFs) hypothesis (4-6). The former assumes nonoptimum maturation of the oocyte during the seasonal transitions in the mother due to inappropriate hormonal feedback, comparable with other conditions in maternal reproductive life, e.g. menarche, menopause, postpregnancy restoration of the ovulation rate, etc. The latter assumes seasonal epidemic pathogens during the mother's pregnancy, or later in life. Agreement, disagreement and discrimination between these competing hypotheses were evaluated. The SPrOO hypothesis appears to have the virtue of raising several testable predictions and of offering more explanatory power. In addition, it incorporates the main stream of knowledge about congenital anomalies and elucidates many constitutional and reproductive enigmas in human reproduction.

Female↗

PubMed1999

Exposure to toluene in the printing industry is associated with subfecundity in women but not in men.

OBJECTIVE: To examine the possible influence of exposure to toluene on human fertility. METHODS: In a cross sectional study, a sample of 150 male and 90 female printing industry workers were interviewed retrospectively on reproductive experience with a modified version of the European study of infertility and subfecundity questionnaire. Exposure categories comprised job descriptions and information on exposure measurements obtained by industrial hygienists. The fecundability ratio (FR) was estimated on the basis of time to pregnancy (TTP) or periods of unprotected intercourse not leading to pregnancy (PUNP) by means of survival analysis with proportional hazard models. Confounders such as age, ethnicity, smoking, parity, pelvic inflammatory diseases, and frequency of sexual intercourse were controlled for in the analyses. RESULTS: 256 Periods of TTP or PUNP were reported by men and 174 by women. After exclusion of induced abortions, birth control failures, and periods without employment for female workers we were able to analyse 169 periods in men and 100 periods in women. Male workers who had been exposed to different concentrations of toluene and their partners did not show a reduction in fecundity. In women (39 periods occurred during exposure) fecundity was reduced (FR 0.47, 95% confidence interval (95% CI) 0.29 to 0.77). Neither, restriction to only the first period nor exclusion of PUNPs changed the results (FR 0.48, 95% CI 0.24 to 0.97). CONCLUSION: After considering possible biases, low daily exposure to toluene in women seems to be associated with reduced fecundity. This result is in accordance with other findings for organic solvents and supports both the hypotheses that (a) organic solvents could affect hormonal regulation, and that (b) organic solvents increase early fetal losses which in turn contributes to longer times of unprotected intercourse.

Adolescent↗