ISSN:1076-2752    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

In decision making, it is often necessary to select between different strategies, and the best decision relies heavily on precise quantitative estimates of risks and benefits of the different strategies. To make such estimates, large samples are needed, but large studies are very expensive and difficult to conduct, especially studies that involve several centers, often in different countries. Before such a study is initiated, other options should be fully explored; if data already exist, it may be possible to combine results into a single estimate. A meta-analysis may be easy to do, but it is difficult to do well; sometimes, a meta-analysis may be grossly misleading. Some of the options and pitfalls in doing a meta-analysis are revealed in the text. The options for a meta-analysis should be considered before a megastudy is launched, and meta-analyses are often a useful way of introducing past experience into inference making.

ISSN:1076-2752    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Some validity aspects related to various sources on pregnancy outcome and exposure are discussed. Register-based data on outcome and exposure are compared with workers’ own reports. The problems in the use of personal interview data on pregnancies are related to the possible selection in recognition and reporting the pregnancy outcome. The best way of avoiding misclassification of outcome is to resort to medical records whenever possible. Misclassification of exposure is most likely a common reason for discrepancies in results in reproductive studies. The misclassification of exposure deflates the power of the study to detect the true difference between exposed and nonexposed subjects, particularly when the prevalence of exposure is low. It is of great importance to confirm, if possible, the exposure status by using two or more independent sources of data.

ISSN:1076-2752    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

The findings and methodological issues of epidemiologic studies on adverse developmental effects of parental occupational exposure to organic solvents are reviewed. The studies on maternal effects suggest that high exposure to solvents may increase the risk of spontaneous abortion, but the findings on congenital malformations are inconsistent. Suggestive associations of spontaneous abortions have also been observed with some particular solvents. The evidence appears to be most adequate for toluene. Evidence on the effects of paternal exposure to solvents on pregnancy outcome is limited and inconsistent. Suggestive results link paternal exposure to spontaneous abortion, congenital malformation, and low birth weight or preterm birth. A common methodological weakness in these studies is the inaccurate data on exposure. Positive findings encourage further studies with an improved study design and methods, particularly with improved assessment of exposure.

ISSN:1076-2752    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

The aim of this article was to summarize the epidemiologic studies on the possible impact of parental occupational exposure to lead or other metals on spontaneous abortion. For paternal exposure, the total number of abortions in the studies with adequate exposure contrast were 340 for lead, 240 for mercury, and 90 for unspecified metals and, correspondingly, for maternal exposure, about 80 for lead, 80 for mercury, 70 for nickel, and 130 for exposure to unspecified metals. Epidemiologic studies indicate that paternal exposure to lead or mercury might be associated with the risk of spontaneous abortion. For maternal exposure, no clear conclusion could be reached. In particular, paternal occupational exposure levels to metals were substantial compared with population values. Even though there are shortcomings in the present knowledge, protective goals for paternal exposure to lead and mercury are warranted. More well-designed studies on metals are needed.

ISSN:1076-2752    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Many kinds of exposures and chemicals have been shown to affect human sperm quantity and quality. This review focuses first on the best known occupational testicular toxin, dibromochloropropane. Prolonged heat is clearly detrimental to spermatogenesis. Studies on occupational heat, radiation, and chemical exposures and their effects on sperm are reviewed. The evaluation of human sperm studies is hampered by inconsistencies in biological analytical methods, in control for confounders, and in weaknesses of study design. Still, there is reason to suggest that human semen parameters can serve as valuable indicators of toxic and, in future, even genotoxic effects of occupational and environmental factors.

ISSN:1076-2752    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

A retrospective time-to-pregnancy study was conducted among women biologically monitored for exposure to lead. The women were participants of a previous study on spontaneous abortion. They were classified into exposure categories on the basis of questionnaire information, and individual blood lead (B-Pb) measurements. The adjusted incidence density ratios (IDR) of clinically recognized pregnancies were. 93 (95% confidence interval [CI]. 56 to 1.57) for very low (B-Pb<.5 μmol/L),. 84 (CI.48 to 1.45) for low (B-Pb. 5 to. 9 μmol/L), and.80 (CI 0.42 to 1.54) for higher (B-Pb <1.0 μmol/L) exposure compared with no exposure, in the discrete proportional hazards analysis. Exposure to inorganic lead was not associated with fecundability at current, low-exposure levels. The suggestive finding among the eight most heavily exposed women (B-Pb 1.4 to 2.4 μmol/L, IDR. 53; CI. 19 to 1.52) should be confirmed or refuted in a larger study.

ISSN:1076-2752    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Exposure to pesticides is inherent in many agricultural jobs. Most of the interest in connection with pesticides and pregnancy outcome has been directed to birth defects. Some indications of an elevated risk of limb anomalies have been associated with ecologic exposure, maternal environmental exposure to pesticides determined by the mother’s place of residence, and parental occupation involving potential pesticide exposure. Orofacial clefts have been related to maternal environmental exposure to pesticides and exposure in agricultural work. Moreover, there is evidence that maternal agricultural occupation and pesticide exposure may be associated with elevated risk of spontaneous abortion and stillbirth. However, some studies have found no indication of reproductive hazards but, altogether, the epidemiologic evidence is inconclusive as regards the risk of adverse pregnancy outcome.

ISSN:1076-2752    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

Pronounced physical exertion may influence intraabdominal pressure and uterine blood flow, hormonal balance, and nutritional status, all of which are important determinants of embryonic and fetal development and survival. Most of the epidemiologic evidence of reproductive effects from occupational physical activity concerns gestational age/premature birth, birth weight/intrauterine growth retardation, and spontaneous abortion. Strenuous work, especially when involving long hours of standing and walking, seems to increase the risk of preterm delivery. The effect on intrauterine growth and spontaneous abortion risk is less clear. As a single factor, heavy lifting has in most circumstances not been associated with a significantly increased risk of these outcomes. In general, heavy work duties should be avoided, and enough rest periods assured, especially in late pregnancy.

ISSN:1076-2752    

出版商:OVID    

年代:1995

数据来源: OVID

摘要:

In addition to having possible direct effects on the fetus, noise induces a stress reaction in the mother, possibly causing reproductive disturbances. In shift work, many physiological functions and systems that are circadian in nature can be disturbed. Study results indicate that occupational noise at the level of approximately 85 dB LAeq(8 h)or higher and shift work, especially rotating schedules, may have independent negative effects on birth weight and length of gestation. Some forms of shift work have also been associated with early fetal loss. Moreover, some results have related noise exposure and shift work to menstrual disturbances and infertility. Although the evidence is not ample, it is prudent to consider exposure to high-level noise and shift work as risks to reproduction.

ISSN:1076-2752    

出版商:OVID    

年代:1995

数据来源: OVID