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The variation in the incidence of cancer between geographic areas and socio-economic classes is outlined. In many instances the differences in the incidence can be attributed to differences in life-style factors such as smoking, diet, sexual habits, and the reproductive history of women. The role of smoking as an explanation of the variation in the risk of lung cancer between occupational groups is emphasized.
OBJECTIVES: This study assessed occupational exposure in dental surgeries on the basis of the reported use of dental materials and techniques and applied waiting-time-to-pregnancy methodology to study fertility in relation to the occupational exposure. METHODS: Data were collected retrospectively using a self-administered postal questionnaire addressing the occupational and reproductive history of the participants. The study groups consisted of 558 female dental surgeons and 450 high school teachers that had given birth in Norway to at least 1 living child. The present study comprised data from a total of 1408 pregnancies. The effects of practicing dentistry and of the given workplace exposure on fertility were analyzed with the discrete proportional hazard regression method. RESULTS: Most of the female dental surgeons were using amalgam for fillings during the period they tried to conceive, and 1/3 placed more than 50 fillings a week. Tooth-colored fillings were in limited use. Prior to 75% of the pregnancies, the dental surgeons reported handling chloroform-based root canal sealers. Forty percent of the dental surgeons were daily exposed to disinfectants containing ethanol and benzene. No difference was found in fertility between the dental surgeons and the high school teachers. Exposure to mercury, chloroform, and benzene was not associated with decreased fertility, except for a possible effect of mercury in the last pregnancy of multiparous dental surgeons. CONCLUSIONS: Occupational exposures had no clear adverse effects on fertility among the female dental surgeons studied.
OBJECTIVES: The aim of this study was to identify risk factors for cardiovascular malformation. METHODS: In a case-referent study prospectively collected data were obtained from original medical records. The study included 277 woman who had infants with a severe cardiac defect, and for each case two referents (medical records study) were included. Data on parental age, maternal reproductive history, disease in early pregnancy, reported maternal use of drugs and alcohol, smoking habits, parental occupation, and maternal body mass index (BMI) were extracted. When data were available from Swedish medical health registers, a comparison was made (register study) between all infants with cardiovascular defects (2208) and all infants born (175 768). RESULTS: Maternal diabetes mellitus was associated with an increased risk for cardiovascular malformation [odds ratio (OR) 2.38, 95% confidence interval (95% CI) 1.36-4.15], as was a high BMI (> 29) (OR 1.46, 95%CI 1.12-1.90). A tendency towards an increased risk was found for involuntary childlessness, spontaneous abortion, thyroid drugs, and nonsteroid anti-inflammatory drugs. CONCLUSIONS: Some known risk factors for cardiac defects (eg, maternal diabetes mellitus and the use of antiepileptics) could be identified. Other postulated risk factors could not be verified, for example, paternal age and parental occupation. The use of medicinal drugs seems not to be a major factor in the etiology of cardiac defects. It is possible, however, that there is an association with the use of nonsteroid anti-inflammatory drugs or drugs for thyroid disease. The relationship between a high BMI and cardiovascular malformation observed in this study may be explained by impaired maternal glucose tolerance.
Microflora of the pouch epithelium of 17 female koalas (Phascolarctos cinereus) were examined in relation to their current reproductive status and recent reproductive history. No microbial growth was observed in pouch swabs from 13 of 17 (76%) koalas, including four females without young, seven with pouch young and two with back young (i.e. permanently emerged from the pouch). Growth of bacteria or yeasts was observed in pouch swabs from four koalas, each of which had experienced mortality of its pouch young during the current breeding season. Seven species of microorganisms were isolated, including Pseudomonas aeruginosa, Serratia marcescens and Enterococcus faecalis. Based on the absence of microflora in the majority of females examined, we propose that the pouch epithelium normally provides a hostile environment for microbial colonization.
In this paper, we examine empirical evidence for a relation between infant and child mortality and fertility in Latin American countries from 1920 to 1990. We investigate the relation at several levels of aggregation and evaluate the extent to which evidence at one level is consistent with evidence at other levels. We first examine aggregate cross-country information over several decades, a type of data typically used in past research on the topic. We also examine yearly series of births, deaths, infant deaths, and socioeconomic indicators for selected countries to track the association between short-term fluctuations in fertility and infant mortality. Finally, we use micro-level data from the Demographic and Health Surveys (DHS) to assess the relation between fertility and child mortality from individual reproductive histories. The evidence we assemble from these different data sets is remarkably consistent and suggests small positive effects of infant mortality on fertility. These effects, however, may be too small to support the hypothesis that changes in child mortality are of more than modest importance in the process of fertility decline in Latin America in the late twentieth century.
An evaluation of a midwife-operated community birthing center was conducted to identify whether it would be safe, cost-effective, and psychologically and socially satisfying for Inuit women in one community in the Northwest Territories. Two nurse-midwives provided antenatal and postnatal care to all pregnant women and delivered those designated as 'low risk' for complications. Another community similar in size but with no community birthing was used for comparison of the three indices. Data were gathered on reproductive histories and pregnancy risk profiles of all women giving birth in a one-year period. The financial costs were calculated for those women transferred out to hospital for delivery and compared with those who stayed in the community. Pregnant women and their partners in both communities, health staff, and community members were interviewed for their feelings and concerns about the birthing services. Preliminary findings suggest that with experienced midwives community births are safe. A minimum of 25 births is required in the community for this project to be cost effective. The women who had their infants in the community expressed satisfaction for a number of reasons.
The preliminary results of an international collaborative study examining premature menopause in fragile X carriers are presented. A total of 760 women from fragile X families was surveyed about their fragile X carrier status and their menstrual and reproductive histories. Among the subjects, 395 carried a premutation, 128 carried a full mutation, and 237 were noncarriers. Sixty-three (16%) of the premutation carriers had experienced menopause prior to the age of 40 compared with none of the full mutation carriers and one (0.4%) of the controls. Based on these preliminary data, there is a significant association between fragile X premutation carrier status and premature menopause.
Cancer of the gallbladder is a rare cancer with a poor prognosis. Most patients die within 1 year. The incidence shows large geographic variation and is higher in females and in certain ethnic groups. Gallstones are closely related to this type of cancer. Studying risk factors such as lifestyle is hampered by the generally small size of the case-series. Nevertheless, the studies conducted so far provide some indication that cigarette smoking, alcohol consumption, obesity and specific dietary habits might affect the risk. In women, reproductive history seems to affect the risk as well. Incidence may be lowered by identifying high risk groups and offering preventive measures. Although gallstones are associated with higher risk, most people with untreated gallstones are at low risk of developing the cancer. Moreover, the cancer occurs at such an old age that prophylactic removal of a stone-containing gallbladder is not an appropriate measure for the prevention of gallbladder cancer. Probably at a higher risk are those who are exposed to stones for longer periods. An indicator of duration of exposure is not presently available; whether stone size can be such an indicator in specific conditions and populations needs to be studied further.
In etiological studies of renal cell carcinoma, the associations between exogenous hormones, reproductive factors, or gynecological operations have not been well examined. Our aim was to evaluate gender-specific risk factors for renal cell carcinoma using data from a population-based case-control study conducted in Los Angeles, California and to elucidate possible underlying mechanisms. A population-based case-control study involving 422 female renal cell carcinoma patients, ages 25-74 years, and an equal number of sex-, age-, and race-matched neighborhood controls was conducted in Los Angeles, California. Detailed information regarding reproductive history, hysterectomy, use of exogenous estrogens, and other medical and lifestyle factors was collected through in-person interviews. Compared to women with an intact uterus, those who had undergone hysterectomy were at an increased risk for renal cell carcinoma (odds ratio, 1.8; 95% confidence interval, 1.3-2.5). Parity and use of estrogen replacement therapy were no longer risk factors for renal cell carcinoma when hysterectomy was adjusted for in the analysis. No association between renal cell carcinoma and use of oral contraceptives was found. Limited epidemiological data do not support an endocrine explanation for the observed hysterectomy-renal cell cancer association. We conjecture that unintentional injury to the ureter during the surgical procedure, which results in renal cell damage and consequent renal cell proliferation, may be a cause of the increased cancer risk in hysterectomized women.
Breast cancer originates in undifferentiated terminal structures of the mammary gland. The terminal duct of the Lob 1 of the human female breast is the site of origin of ductal carcinomas. Cell replication and the concentration of estrogen receptors type at in Lob 1 are at their peak during early adulthood, at a time during which the breast is more susceptible to carcinogenesis, decreasing considerably with aging. More importantly, when treated with carcinogens in vitro they express phenotypes indicative of cell transformation. These studies indicate that in humans there is a target cell of carcinogenesis, which is found in a specific compartment whose characteristics are a determinant factor in the initiation event. These target cells will become the stem cells of the neoplastic event, depending upon: a) topographic location within the mammary gland tree, b) age at exposure to a known or putative genotoxic agent, and c) reproductive history of the host. Epidemiological findings such as the higher incidence of breast cancer in nulliparous women and in women having early menarche support this concept, because it parallels the higher cancer incidence elicited by carcinogens when exposure occurs at a young age. In addition, it has been shown that increase in parity is associated with a pronounced decrease in the risk of breast cancer, each additional live birth conferring a 10% risk reduction. Thus, the protection afforded by early full-term pregnancy in women could be explained by the higher degree of differentiation of the mammary gland at the time in which an etiologic agent or agents act. The relevance of our work lies in the side by side comparison of in vivo and in vitro studies in the human breast that validates experimental data for extrapolation to the human situation. The finding that cell proliferation is of importance for cancer initiation, whereas differentiation is a powerful inhibitor, provides novel tools for developing rational strategies for breast cancer prevention and control.
Holoprosencephaly is a developmental field defect manifested by a spectrum of abnormalities of the forebrain and midface. Approximately 50% of holoprosencephaly cases are associated with a cytogenetic abnormality or a monogenic syndrome. Suggested risk factors for the remaining 50% of cases have been described in case reports, but have not been confirmed in systematically conducted studies. We report the results of a population-based case-control study of holoprosencephaly. Live births, fetal deaths, and terminations with a diagnosis of cytogenetically normal holoprosencephaly were identified by the California Birth Defects Monitoring Program. Telephone interviews were conducted with the mothers of 58 cases and 107 live born, nonmalformed controls. Women were questioned about their health and reproductive histories, family demographics, and exposures occurring during their pregnancies. Among nonsyndromic cases, increased risks were observed for females (OR=1.8, 95% C.I. 0.9-3.9), foreign-born vs. U.S. or Mexico-born women (OR=3.1, 95% C.I. 1.1-8.6), and women with early menarche (OR=2.3, 95% C.I. 0.9-5.7). Maternal periconceptional exposures associated with increased risks for nonsyndromic holoprosencephaly included alcohol consumption (OR=2.0, 95% C.I. 0.9-4.5), cigarette smoking (OR=4.1, 95% C.I. 1.4-12.0), and combined alcohol and smoking (OR=5.4, 95% C.I. 1.4-20.0), insulin-dependent diabetes (OR=10.2, 95% C.I. 1.9-39.4), medications for respiratory illnesses (OR=2.3, 95% C.I. 0.9-6.0), and salicylate-containing medications (OR=2.5, 95% C.I. 0.8-7.9). These findings are consistent with risk factors identified in some previous reports, and identify several new potential risk factors that require confirmation in future studies.
Under the current family planning policy in China, the criterion for evaluating all parties involved in the birth planning system provides an incentive for everyone to see that the policy is met, either in reality through strict enforcement of family planning regulations, or statistically through manipulation of statistical records. We investigate underreporting of births in four rural counties of northern China, using data from a 1992 sample survey featuring a reproductive history. To clarify the mechanisms of underreporting, we focus on the ways in which reporting errors may affect the distribution of first births by time since marriage. The results of our investigation suggest that in three of the four counties, first-birth intervals are lengthened by underreporting of girl babies and by replacing them with second births reported as first births.
A cross-sectional survey of the wood furniture industry was conducted in southern Thailand in February 1993. The aim was to examine the manufacturing process, occupational hazards at the workplace, workers' demographic characteristics, period of employment, incidence rate of work related injury and some reproductive history of workers. Altogether 69 managers and 1,000 workers participated in the study. There are 2 main types of wood industry, rubberwood and hardwood. The rubberwood industry is semi-automated with advanced technology, has a female-dominated workforce of 200-300 workers per factory and overseas-market orientation. The hardwood industry is based in small-scale workplaces ranging from 20 to 60 workers, domestic-market orientation and has a male-dominated workforce. Most of the workers were young, single, of low education and were high turnover rate laborforce, with arduous work and long working hours per week. Solvent was the most frequent chemical exposure. The person-year incidence of chemical exposure in female workers was higher than in male workers for every group of chemicals. The incidence of accidents was twice as high as the official rate. The standardized fertility ratio of female wood workers was only 51.6% of that of the Thai female population. There was a high abortion rate among women who became pregnant inside the wood industry compared to that among pregnancies outside the wood factory. Wood industry workers were exposed to occupational hazards and accident-prone work conditions.
OBJECTIVES: To determine the prevalence of antibodies to Chlamydia trachomatis in women presenting with ectopic pregnancies to Groote Schuur Hospital. METHODS: C. trachomatis antibody titres were measured using a modified micro-immunofluorescence test in women presenting with ectopic pregnancy. Control subjects were drawn from women with term pregnancies and an uneventful reproductive history. RESULTS: Seventy-four patients and controls were studied. Demographic variables were controlled for at time of entry into the study. A significant association between the number of lifetime sexual partners and exposure to C. trachomatis was noted (P = 0.001). Patients with ectopic pregnancies had significantly higher antibody titres than control subjects (P = 0.001), and in both groups the prevalence of background antichlamydial antibody was high (ectopic pregnancies 59%, pregnant controls 32%). CONCLUSIONS: While the role of C. trachomatis infection in women who develop ectopic pregnancies needs to be explored further, it seems wise to treat them all with empirical antibiotics at the time of presentation.
Preeclampsia is a pregnancy-specific syndrome, it occurs in approximately 5-10% of all pregnancies and the etiology remains unknown, but the primigravida adolescent as such as multigravid older women whom have conceived with a new sexual partner have a greater risk, this has been associated also with the use of barrier contraceptive methods that prevent exposure to sperm with the endometrial cavity. An immunological factor has been suspected because fetal antigen's could cause antigenic reaction with the maternal immunological apparatus, for first exposure at these antigens, since the fetus is considered like an allotransplantation. This is supported in some studies that report that the use of condoms, spermicides and withdrawal are associated with developing of preeclampsia in subsequent pregnancy, and another hand indicate at cohabitation preceded for long period, practiced oral sex and use of contraceptive methods that permit exposure to sperm viable with uterus decreased the prevalence of preeclampsia. To test this hypothesis, we initially used data from two groups of pregnant women, comparing the contraceptive and reproductive history of 73 pregnant women with preeclampsia and 70 pregnant women without preeclampsia. The odds ratio for preeclampsia indicated a 2.52-fold (with 95% confidence interval, 1.17 to 5.44, p < 0.05), increased risk of preeclampsia for users of barrier contraceptives compared with women using nonbarrier contraceptives methods. Other variables like socio-demographic and obstetrics analysis were not different between both groups. This study suggest that nonbarrier contraceptive methods or the exposure of paternal spermatic antigens is protective against development of preeclampsia. Further immunological studies are necessary to determine the role of contraception methods and preeclampsia.
Various factors have been found to be predictors of the relative risk of breast cancer (Table 2). Epidemiologic variables influencing breast cancer risk include age, marital status, geographic location, racial or ethnic extraction, and socioeconomic status. The risk of developing mammary carcinoma is increased with advancing age, among unmarried women, in the United States and Europe, and among women of higher socioeconomic classes. Conversely, a decreased breast cancer risk is observed among fertile married women in Asian countries, among Oriental women, and in lower socioeconomic classes. Reproductive history plays an important role in determining breast cancer risk. The risk of developing mammary carcinoma is increased by an early menarche and decreased by delayed first menses. A late natural menopause increases breast cancer risk while an early oophorectomy offers protection. Hormonal factors are thought to play important roles in the etiology of breast cancer, but the contributions of estrogenic and androgenic influences to mammary neoplasia have not been delineated. Certain estrogen fractions have been implicated as mammary carcinogens, while certain adrenal androgenic steroids have been shown to be promotors of breast cancers. Chronic cystic mastitis is associated with an increased breast cancer risk. A positive family history increases the risk of developing mammary carcinoma and a past history of breast cancer markedly increases the possibility of subsequent breast neoplasia.
OBJECTIVE: A high proportion of stunting and wasting in children under-five has been reported from developing countries. This paper presents the nutritional status of a two year cohort of urban squatter children in Karachi, Pakistan and assesses risk factors for wasting and stunting at the reference ages of six, twelve and twenty-four months. METHODS: A birth cohort of 738 children were visited at specific intervals by trained nurses to collect information on anthropometric measurements, feeding practices and intercurrent illnesses. Socioeconomic and demographic information included water and sanitation facilities, availability of electricity, type of house construction material and average monthly income. Information about the mother's reproductive history was also obtained. RESULTS: At two years the proportion of stunting and wasting was 41.8% and 10.6% respectively. Intrauterine growth retarded children had a higher risk of stunting and wasting at all reference ages as compared to children who were appropriate for gestational age. In the logistic regression models, intrauterine growth retardation was the only significant risk factor that remained in all models at each reference age. CONCLUSION: The consistent association of IUGR for stunting and wasting adds to the growing body of evidence that by improving maternal health we will ultimately break the vicious cycle of malnourishment and improve the health and well-being of future generations. We suggest interventions to improve the nutritional status of Pakistani urban children living in squatter settlements focused on mothers and children.
Predictors and the prevalence of adverse birth outcomes among 237 homeless women interviewed at 78 shelters and meal programs in Los Angeles in 1997 were assessed. It was hypothesized that they would report worse outcomes than national norms, that African Americans would report the worst outcomes because of their greater risk in the general population, and that homelessness severity would independently predict poorer outcomes beyond its association with other adverse conditions. Other predictors included reproductive history, behavioral and health-related variables, psychological trauma and distress, ethnicity, and income. African Americans and Hispanics reported worse outcomes than are found nationally, and African Americans reported the worst outcomes. In a predictive structural equation model, severity of homelessness significantly predicted low birth weight and preterm births beyond its relationship with prenatal care and other risk factors.