Effects of ultrasound, shortwaves, and physical exertion on pregnancy outcome in physiotherapists.

STUDY OBJECTIVE--The aim of the study was to investigate whether occupational exposure among physiotherapists is associated with spontaneous abortion or congenital malformation in the offspring. DESIGN--The study was a retrospective nested case-control study, where the pregnancy outcome data were based on the medical registers. SETTING--All registered physiotherapists in Finland who had become pregnant during the study period were included in the study. SUBJECTS--Cases were defined as women who had been treated for spontaneous abortion during 1973-1983 or had delivered a malformed child during 1973-1982. One pregnancy per woman was randomly selected for the study. Three age matched (+/- 18 months) controls were selected for each abortion case and five for each malformation case. The final study population was 204 cases and 483 controls in the spontaneous abortion study, and 46 cases and 187 controls in the congenital malformation study. MEASUREMENTS AND MAIN RESULTS--Exposure information was collected by mailed questionnaires from 1329 women. The response rate was 92% in the spontaneous abortion study, and 89% in the congenital malformation study. Heavy lifting (including patient transfers) was associated significantly with spontaneous abortion. Exposure to ultrasound and shortwaves showed about threefold odds ratios for spontaneous abortions occurring after the 10th week of gestation but in analysis where potential confounding variables were controlled, neither reached statistical significance. Deep heat therapies together, and shortwaves alone, were associated significantly with congenital malformations, but the increase was found in the lower exposure category only. From the potential confounding variables, previous abortion (spontaneous or induced) was associated significantly with spontaneous abortion, and febrile disease in early pregnancy was associated with congenital malformation. CONCLUSION--Physical exertion during early pregnancy seems to be a risk factor for spontaneous abortion. The findings raise suspicion of the potential harmful effect of shortwaves and ultrasound on the pregnancy, but no firm conclusion can be drawn on the bases of these results alone.     

Adverse pregnancy outcome and childhood malignancy with reference to paternal welding exposure.

Welding may deteriorate spermatogenesis and increase reproductive failures. This study examines reproductive end points in a Danish cohort of 10,059 metalworkers who fathered 3,569 children in 1973 through 1986. Occupational histories were gathered by postal questionnaires. Information on pregnancy outcomes and offspring was obtained by record linkage to medical registers. The occurrence of reduced birthweight, preterm delivery, infant mortality, and congenital malformation was not increased among children at risk from paternal welding exposure in comparison with children not at risk. The overall incidence of childhood malignancies among 23,264 children born in 1968 through 1986 with a total of 259,113 person-years of follow-up was equal to national rates (relative risk 0.97, 95% confidence interval 0.63-1.42). However, pregnancies preceding a birth at risk from paternal exposure to stainless steel welding were more often terminated by spontaneous abortion (odds ratio 1.9, 95% confidence interval 1.1-3.2). This finding needs cautious interpretation and should be further investigated in future studies.     

Effect of parents' occupational exposures on risk of stillbirth, preterm delivery, and small-for-gestational-age infants

Epidemiologic research on the effects of parental occupational exposures on fetal development has been limited. The National Natality and Fetal Mortality surveys obtained applicable data on probability samples of live births and fetal deaths which occurred in the US in 1980 among married women. Analyses were conducted for case groups of stillbirths (2,096 mothers, 3,170 fathers), preterm deliveries (less than 37 weeks completed gestation) (363 mothers, 552 fathers), and small-for-gestational-age infants (218 mothers, 371 fathers) compared with controls. Occupational exposures were defined by industry of employment and by imputed exposures based on a job-exposure linkage system. For stillbirth, maternal work in the rubber, plastics, and synthetics industry (odds ratio (OR) = 1.8, 95% confidence interval (Cl) 0.8-4.0) and lead exposure (OR = 1.6, 95% Cl 0.8-3.1), and paternal employment in the textile industry (OR = 1.9, 95% Cl 1.2-2.9), had the largest odds ratios. Preterm birth was most strongly associated with maternal lead exposure (OR = 2.3, 95% Cl 0.7-7.0), corroborating previous findings. Twofold increased risk of preterm delivery was found with paternal employment in the glass, clay, and stone; textile; and mining industries. Paternal exposures to x-rays and polyvinyl alcohol were associated with 1.5-fold increase in risk. The occupation of the mother was not associated with delivery of a small-for-gestational-age infant, in contrast to paternal employment in the art (OR = 2.6, 95% Cl 1.2-5.6) and textile industries (OR = 2.5, 95% Cl 1.3-4.7). Several toxic agents were associated with risk elevation of 1.3 or greater for fathers, most notably benzene (OR = 1.5, 95% Cl 1.1-2.3). In spite of limitations in the exposure data, the size of the exposed populations, and possible confounding, the results in this study encourage further evaluation of the effects of maternal exposure to lead and possibly solvents, as well as paternal exposure in the textile industry and to x-rays and benzene.     

Paternal exposure to lead and infertility

To assess whether paternal exposure to lead is associated with infertility, we performed a register-based study among married men biologically monitored for exposure to inorganic lead. We obtained information about the marriages and the wives of the men from the Finnish Central Population Register. Data on pregnancies were obtained from medical records. Paternal exposure to lead was assessed on the basis of blood lead measurements. We estimated the risk of infertility, defined as nonoccurrence of a marital pregnancy, by applying binomial regression. For the blood lead categories of 0.5-0.9, 1.0-1.4, 1.5-1.9, 2.0-2.4, and > or =2.5 micromol/L the relative risk of infertility, compared with the risk in the lowest exposure category (<0.5 micromol/L), was 1.27 (95% confidence interval 1.08-1.51), 1.35 (1.12-1.63), 1.37 (1.08-1.72), 1.50 (1.08-2.02), and 1.90 (1.30-2.59), respectively. The findings support the hypothesis that paternal exposure to lead increases the risk of infertility at low occupational exposure levels. We applied proportional hazards regression to the analysis of pregnancy delay. A delay was observed among the wives of men exposed to lead. Exposure to lead was not clearly associated with delayed pregnancy, however, when the analysis was restricted to couples with at least one pregnancy. This finding suggests that the restriction of the study on time to pregnancy to fertile couples may introduce a bias toward no association.     

Time to pregnancy among the wives of men occupationally exposed to lead

We conducted a retrospective study on time to pregnancy among the wives of men biologically monitored for lead to assess whether paternal occupational exposure to inorganic lead is associated with decreased fertility. After three mailings, 554 (72.2%) wives of the monitored men participated. The final study population consisted of 502 couples who did not use contraception at the beginning of the pregnancy. We assessed lead exposure from blood lead measurements and from questionnaires completed by the men. We calculated the relative fecundability density ratios with discrete proportional hazards regression. The fecundability density ratios, adjusted for potential confounders, were 0.92 [95% confidence interval (95% CI) = 0.73-1.16], 0.89 (95% CI = 0.66-1.20), 0.58 (95% CI = 0.33-0.96), and 0.83 (95% CI = 0.50-1.32) for blood lead categories 0.5-0.9, 1.0-1.4, 1.5-1.8, and > or =1.9 micromol/L, respectively, as compared with <0.5 micromol/L. The findings provide limited support for the hypothesis that paternal exposure to lead is associated with decreased fertility.     

Video display terminal use during pregnancy and reproductive outcome--a meta-analysis.

STUDY OBJECTIVE--The aim was to obtain quantitative information from published data on the potential association between video display terminal (VDT) use during pregnancy and the outcome. DESIGN--Results of nine published case-control studies (or cohort studies analysed as case-control) on the relation between VDT exposure during pregnancy and the outcome were sought by reviewing reference lists in relevant reports and by conducting manual and computer searches of the reports published in English. MEASUREMENTS AND MAIN RESULTS--The nine reviewed reports included information on about 9000 cases of spontaneous miscarriages, 1500 of low birth weight, 2000 of congenital malformation, and 50,000 controls. The results of these studies on each outcome of pregnancy examined were reduced to a single 2 x 2 table (cases/controls--exposed/unexposed). Pooled odds ratio (OR) estimates were computed separately for miscarriage, low birth weight, and congenital malformation. Seven studies analysed the relation between VDT exposure in pregnancy and the risk of miscarriage: the estimates' crude OR of spontaneous abortion ranged from 0.9-1.2 and the pooled OR was 1.0 (95% confidence interval (CI) 0.9, 1.0). No consistent evidence of increasing risk with duration of exposure to VDT was found. Two studies analysed the relation between VDT use and risk of having a low birth weight infant: the OR estimates in the individual studies were 1.0 and 1.1. Likewise, no relation emerged from the five studies providing information on congenital malformations and VDT use: the pooled OR was 1.0 (95% CI 0.9, 1.2). No specific malformation pattern emerged. CONCLUSIONS--This meta-analysis provides reassuring evidence on the absence of any major risk of adverse pregnancy outcome as a result of exposure to a VDT. With the number of cases reviewed, it was possible to exclude excess risk of 20% for spontaneous abortion, low birth weight, and congenital malformations.     

尿道下裂危险因素的病例对照研究

目的 探讨尿道下裂病因。方法 采用以医院为基础的1:2配比的病例对照研究方法,以统一的调查表及调查方式对107倒尿道下裂及214例对照进行面对面问卷调查,应用SAS 6.12软件对所有调查因素进行单因素及多因素logistic回归分析。结果 胎儿尿道下裂的发生与母亲孕前自然流产史(OR=3.87,95％CI:1.60～9.39)、孕期发生先兆流产(OR=3.57,95％CI:1.31～9.64)、孕早期感冒伴发热(OR=7.63,95％CI:2.50～23.24)、孕中期用抗感染和/或解热止痛药(OR=16.46,95％CI;3.46～78.21)、父亲职业性接触农药(OR=3.70,95％CI:1.49～9.16)及胎儿低出生体重(OR=12.62,95％CI:2.97～53.67)呈正相关,与母亲孕早期增加蛋白质类营养(OR=0.33,95％CI:O.15～0.74)呈负相关。结论 母亲孕前自然流产史、孕期发生先兆流产、孕早期感冒伴发热、孕中期用抗感染和/或解热止痛药、父亲职业性接触农药、胎儿低出生体重等可能增加胎儿发生尿道下裂的危险,而母亲孕早期增加蛋白质类营养可能降低胎儿发生尿道下裂的危险。     

Parental exposure to polycyclic aromatic hydrocarbons and the risk of childhood brain tumors: The SEARCH International Childhood Brain Tumor Study

Experimental evidence suggests that parental exposure to polycyclic aromatic hydrocarbons (PAH), which occurs primarily through tobacco smoke, occupational exposure, and air pollution, could increase the risk of cancer during childhood. Population-based case-control studies carried out in seven countries as part of the SEARCH Program compared data for 1,218 cases of childhood brain tumors and 2,223 controls (1976-1994). Parental occupational exposure to PAH during the 5-year period before birth was estimated with a job exposure matrix. Risk estimates were adjusted for child's age, sex, and study center. Paternal preconceptional occupational exposure to PAH was associated with increased risks of all childhood brain tumors (odds ratio (OR) = 1.3, 95% confidence interval: 1.1, 1.6) and astroglial tumors (OR = 1.4, 95% confidence interval: 1.1, 1.7). However, there was no trend of increasing risk with predicted level of exposure. Paternal smoking alone (OR = 1.4) was also associated with the risk of astroglial tumors in comparison with nonsmoking, non-occupationally-exposed fathers. Risks for paternal occupational exposure were higher, with (OR = 1.6) or without (OR = 1.7) smoking. Maternal occupational exposure to PAH before conception or during pregnancy was rare, and this exposure was not associated with any type of childhood brain tumor. This large study supports the hypothesis that paternal preconceptional exposure to PAH increases the risk of brain tumors in humans.     

Paternal occupational lead exposure and spontaneous abortion

A case-referent study was conducted on whether occupational exposure of men to inorganic lead is related to spontaneous abortion in their wives. The men were biologically monitored for lead exposure. The cases (213 spontaneous abortions) and referents (300 births) were identified from medical registers. Lead exposure was assessed with blood lead (PbB) measurements and data obtained from a questionnaire. The results did not show a statistically significant relationship between spontaneous abortion and paternal lead exposure among all the study subjects. A significant increase was observed in the risk of those women whose husbands had been monitored (PbB greater than or equal to 1.5 mumol/l) during or close to the time of spermatogenesis. The association between lead exposure and spontaneous abortion was modified also by the age of the wife and paternal alcohol use. The findings suggest that there may be an association between paternal lead exposure and the risk of spontaneous abortion.     

隐睾发生的危险因素研究

目的：研究隐睾发生的危险因素。方法：采用以医院为基础的1：2配比的病例对照研究方法，按统一的调查方法对99例隐睾及198例对照组面对面问卷调查。应用SAS6。12软件对所调查因素进行单因素及多因素logistic回归分析，结果：胎儿隐睾与母亲孕早期感冒伴发热（OR＝9．37，95％CI：2．25－39．09），孕期发生先兆流产（OR＝4．66，95％CI，2．02＝10．74），孕期发生先兆子痫（OR＝16．33，95％CI：1．40－191．20），父亲职业性接触农药（OR＝12．79％CI；2．90－56．43），低出生体重（OR＝5．77，95％CI：1．39－23．98），母亲怀孕年龄＜24（OR＝2．89，95％CI：1．29－4．06）呈正相关。结论：母亲孕早期感冒伴发热，孕期发生先兆流产及先兆子痫，父亲职业性接触农药，低出体重，母亲怀孕年龄＜24岁是隐睾发病的主要危险因素。     

Spontaneous abortion, sex ratio, and paternal occupational exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin.

There is conflicting research regarding an association between fetal death and paternal exposure to Agent Orange, a phenoxy herbicide widely used in Vietnam that was contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Men who worked in the U.S. factories that produced Agent Orange were exposed to TCDD at levels hundreds of times higher than TCDD levels in the general population. Wives of TCDD-exposed chemical workers and wives of nonexposed neighborhood referents were interviewed to determine reproductive history. Paternal serum TCDD level at time of conception was estimated for each pregnancy using serum samples taken in 1987. Estimated TCDD levels of workers during or after exposure were high (median, 254 ppt; range, 3-16,340 ppt) compared to referent levels (median, 6 ppt; range, 2-19 ppt). No association between paternal TCDD level at the time of conception and spontaneous abortion was observed among pregnancies fathered by workers with TCDD levels of < 20 ppt [odds ratio (OR) = 0.77; 95% confidence interval (CI), 0.48-1.22], 20 to < 255 ppt (OR = 0.81; 95% CI, 0.40-1.63), 255 to < 1,120, (OR = 0.69; 95% CI, 0.30-1.58), and >or= 1,120 ppt (OR = 0.95; 95% CI, 0.42-2.17) compared to pregnancies fathered by referents. The sex ratio [males/(males + females)] of offspring also did not differ by TCDD exposure (0.53 and 0.54 among workers and referents, respectively). We did not find an association between paternal serum TCDD level and spontaneous abortion or sex ratio of offspring in this population. The estimated TCDD levels in this exposed worker population were much higher than in other studies, providing additional evidence that paternal TCDD exposure does not increase the risk of spontaneous abortion at levels above those observed in the general population. The study could not evaluate the effect of father's childhood or prenatal TCDD exposure on subsequent sex ratio.     

Maternal occupational exposure and congenital malformations.

A case-referent study was conducted to assess the risk of congenital malformations in relation to maternal occupational exposure before and during pregnancy. Three hundred and twenty-five cases of major malformations and 325 normal (at birth) referents identified in 15 maternity hospitals were included in the study. The occupational history obtained from an interview of the mother was blindly reviewed by an industrial hygienist who assessed the presence of chemical exposure and the probability of exposure. The results suggested that mothers of the case children with oral clefts were more often exposed to solvents during pregnancy [odds ratio (OR) 7.9, 90% confidence interval (90% CI) 1.8-44.9] and worked more often as cleaners (four cases, no referents). Digestive anomalies (OR 11.9, 90% CI 2.0-149) and multiple anomalies (OR 4.5, 90% CI 1.4-16.9) were also associated with occupational exposure to solvents at work. These results were not modified when differences in maternal age, area of residence, and socioeconomic status were taken into account.     

家族史及环境因素交互作用与子代先天畸形关系的定量研究

目的探讨家族史及环境因素与先天畸形的关系及其交互作用，定量分析可干预因素的预防分值。方法采用病例对照研究设计，选择符合纳入标准的185例先天畸形作为病例组，选择等量的正常儿作为对照组。对病例组和对照组的母亲进行问卷调查及标本检测，数据采用单因素和多因素非条件Logistic回归分析。结果Logistic回归分析有意义的因素为：家族史、孕早期发热、孕早期营养差、负性事件刺激、巨细胞病毒感染，比值比（OR）及其95％可信区间（95％CI）分别为：3．47（1．70～7．06）、2．74（1．17～6．42）、3．07（1．68～5．74）、1．84（1．00～3．37）、3．04（1．61～5．78），先天畸形阳性家族史与上述四个因素之间存在正交互作用，交互作用的超额相对危险度（RERI）分别为2．94、3．88、1．79、3．53；给定条件下可计算出全面控制可干预因素人群预防分值接近10％。结论先天畸形家族史和环境因素间存在正交互作用；采取高危策略可降低人群中先天畸形的患病风险。     

Congenital malformations and maternal occupation: a registry based case-control study.

OBJECTIVES: To investigate the relations between congenital malformations and maternal occupation during pregnancy with a registry based case-control study. METHODS: Analysis was performed on data derived from the Florence Eurocat registry surveillance programme. The study included cases with isolated conditions, including chromosomal anomalies (n = 1351), cases with multiple anomalies registered during the 1980-91 period (n = 440), and babies with no congenital malformations recognised at birth who were born from 1982 to 1989 and selected as controls (n = 3223). 11 categories were defined, 10 including cases with isolated malformations and one for cases with multiple congenital anomalies. Four categories of maternal occupation were selected for the study. Odds ratio (OR) values were adjusted for maternal origin, maternal and paternal education, number of previous live births, illness during pregnancy, and maternal age when the group of chromosomal anomalies was analysed. RESULTS: A notable and significant association between oral clefts and mothers involved in leather and shoe manufacturing was found (adjusted OR 3.9; 99% confidence interval (99% CI) 1.5 to 9.8) and the risk consistently increased when considering cases with isolated cleft palate separately (OR 5.4; 95% CI 1.8 to 13.4). Moreover, a significant risk was identified for the association between multiple anomalies and textile dye workers (adjusted OR 1.9; 99% CI 1.0 to 3.8). CONCLUSIONS: This study indicates a notable, significant relation between maternal occupation as a pelt or leather worker and orofacial clefts in offspring. This finding is in agreement with the suggested inheritance models. The dilution effect due to studying large and heterogeneous groups of workers and occupations limits the value of the study; but it provides a good example of the use of a large database to search for teratogenic risk with the aid of malformation registries.     

先天性泌尿生殖系统结构畸形危险因素的研究

目的：探讨有关因素在先天性泌尿生系统结构畸形发病中的作用。方法：采用成组匹配的病列对照研究方法。对95例患先天性泌尿生殖系统 的围产儿和160例对照围产儿及其父母的情况进行调查。采用非条件logistic回归模型进行多因素分析,计算OR值及OR的95％可信限。结果：先天性泌尿生殖系统结构畸形多发生于男性围产儿（性别成比为74．7％,X^2＝74．863,P＝0．001）,多元逐步回归分析表明：母亲孕早、中期感冒（OR＝7．034,95％CI＝3．488－14．187）、低出生体重（OR＝4．075,95％CI＝1．774－9．362）、孕次≥2（OR＝3．133,95％CI＝1．514－6．483）及母亲孕前职业性接触有害化学物质（OR＝10．496,95％CI＝1．053－104．651）为先天性泌尿生殖系统结构畸形的危险因素,结论：胎儿男性别,母亲孕早、中期感冒、低出生体重,母亲孕次≥2及孕前职业性接触有害化学物质与胎儿发生先天性泌尿生系统畸形有关联。     

Risk of congenital malformations associated with proximity to hazardous waste sites.

Concern about environmental pollutants has increased; however, it remains unclear whether chronic exposures to toxic chemicals in the environment occur at doses sufficient to produce adverse health effects in humans. To date, community studies have not adequately addressed this question. In this study, the authors linked two existing data bases of the New York State Department of Health to evaluate the relation between congenital malformations and residential proximity to hazardous waste sites in New York State. A total of 9,313 newborns with congenital malformations and 17,802 healthy controls living in proximity to 590 hazardous waste sites in 1983 and 1984 were evaluated. After the authors controlled for several possible confounding factors, results indicated that maternal proximity to hazardous waste sites may carry a small additional risk of bearing children with congenital malformations (odds ratio (OR) = 1.12, 95% confidence interval (Cl) 1.06-1.18). Higher malformation rates were associated with both a higher exposure risk (no exposure risk: OR = 1.00; low exposure risk: OR = 1.09, 95% Cl 1.04-1.15; high exposure risk: OR = 1.63, 95% Cl 1.34-1.99) and documentation of off-site chemical leaks (not exposed: OR = 1.00; exposed, but no leaks at site: OR = 1.08, 95% Cl 1.02-1.15; exposed, and leaks found at site: OR = 1.17, 95% Cl 1.08-1.27). The increased rates detected may be important in terms of their public health implications. Further research is necessary to strengthen causal inferences regarding the teratogenicity, of waste site exposure.     

Paternal occupation and congenital anomalies in offspring.

This paper presents the results of an exploratory case-control study of paternal occupation as a risk factor for birth defects in offspring. With the use of a population-based registry in British Columbia, 14,415 liveborn children with birth defects were identified for the period, 1952-1973. Two controls were matched to each case by using the birth files of British Columbia. Paternal occupation was obtained from the birth certificate. The analysis included 20 birth defect categories. Paternal occupations found to be associated with an increased odds ratio (OR) of birth defects include janitors [hydrocephalus (OR = 5.04), ventricular septal defects (OR = 2.45), other heart defects (OR = 2.35)], forestry and logging workers [congenital cataract (OR = 2.28), atrial septal defects (OR = 2.03), syndactyly (OR = 2.03)], painters [spina bifida (OR = 3.21), patent ductus arteriosus (OR = 2.34), cleft palate (OR = 3.36)], printers [atresia of the urethra (OR = 4.50), clubfoot (OR = 2.18)], and plywood mill workers [patent ductus arteriosus (OR = 2.52), pyloric stenosis (OR = 4.12), dislocated hip (OR = 2.71)]. This study has several limitations and the results must be viewed with caution. Nonetheless, the study provides new leads for further evaluation of the role of father's occupation in the etiology of birth defects.     

Occupational paternal exposure to benzene and risk of spontaneous abortion.

OBJECTIVE--The purpose of this study was to evaluate the risk of spontaneous abortion among the wives of male workers occupationally exposed to benzene. METHODS--The wives of 823 men working in two chemical plants at the time of the study were asked to complete a questionnaire describing their pregnancies. The analysis of the 1739 pregnancies that ended in a spontaneous abortion or a birth is presented. The firms' payroll records provided all workers' employment history, including dates. Benzene exposure, graded at two levels (< 5, > or = 5 ppm), was determined for every job, so that benzene exposure for each worker's entire professional life (at these companies) could be assessed. This information was linked to the dates of the pregnancies reported in the questionnaires to enable the exposure status of each pregnancy to be defined (1270 non-exposed and 274 exposed). The frequency of spontaneous abortion, defined as the number of spontaneous abortions divided by the total of spontaneous abortions and births was evaluated. RESULTS--When adjusted for tobacco consumption, mother's age and pregnancy order, the odds ratio of the association between paternal exposure to approximately 5 ppm of benzene and the risk of spontaneous abortion was close to and statistically not different from unity (OR = 1.1; 95% CI (0.7-1.8). CONCLUSION--In this study paternal exposure to benzene did not increase the risk of spontaneous abortion.