Maternal smoking in pregnancy: does it increase the risk of childhood cancer?

Experimental studies show that some compounds in tobacco smoke are transplacental carcinogens, but epidemiological data on maternal smoking and childhood cancer are inconclusive. Using the national Swedish Medical Birth and Cancer Registries, the incidence of cancer was followed through 1987 in a cohort of 497,051 children born 1982-1987 for whom information was available on maternal smoking at 2-3 months of pregnancy. A total of 327 cancers appeared including 198 solid tumours and 129 cancers of the lymphatic and haematopoietic system. The overall relative risk for cancer in children with mothers reporting smoking during pregnancy was 0.99 (95% confidence interval (CI): 0.78-1.27). Corresponding risks for solid tumours and cancers of the lymphatic/haematopoietic system were 0.96 (0.70-1.32) and 1.04 (0.71-1.52), respectively. There was no consistent increase in risk for cancer of different sites or in relation to number of cigarettes smoked per day.     

Maternal smoking during pregnancy and childhood obesity

A recent cohort study suggested that maternal smoking during pregnancy might be a risk factor for childhood obesity. Data from the obligatory school entry health examination in six Bavarian (Germany) public health offices in 1999-2000 were used to assess the relation between maternal smoking during pregnancy and childhood obesity (n = 6,483 German children aged 5.00-6.99 years). A body mass index greater than the 90th percentile was defined as overweight, and a body mass index greater than the 97th percentile was defined as obesity. The main exposure was maternal smoking during pregnancy. The prevalences of overweight and obesity, expressed as percentages, increased in the following order: never smoked (overweight: 8.1, 95% confidence interval (CI): 7.2, 9.0; obesity: 2.2, 95% CI: 1.7, 2.7); less than 10 cigarettes daily (overweight: 14.1, 95% CI: 11.1, 17.7; obesity: 5.7, 95% CI: 3.7, 8.2); and 10 or more cigarettes daily (overweight: 17.0, 95% CI: 10.1, 26.2; obesity: 8.5, 95% CI: 3.7, 16.1). The adjusted odds ratios for maternal smoking during pregnancy were 1.43 (95% CI: 1.07, 1.90) for overweight and 2.06 (95% CI: 1.31, 3.23) for obesity. A dose-dependent association between overweight/obesity and maternal smoking during pregnancy was observed that could not be explained by a wide range of confounders, suggesting that intrauterine exposure to inhaled smoke products rather than lifestyle factors associated with maternal smoking accounts for this finding.     

吸烟、被动吸烟与肺癌发病风险的病例对照研究

目的 探讨吸烟、被动吸烟与肺癌的关联.方法 采用病例对照研究设计,面访肺癌新发病例1 303例和按性别、年龄(±2岁)频数匹配的健康对照1 303例.结果 吸烟是男性肺癌的重要危险因素(调整OR=4.974,95％ CI:3.933 ～6.291),随着开始吸烟年龄提前、吸烟年限延长、日吸烟量、吸烟包年以及吸烟深度的增加,患肺癌危险性增高,呈剂量反应关系(Ptrend＜0.001),戒烟≥10年患肺癌的危险性降低45.4％.男性吸烟患肺鳞癌的危险性比患肺腺癌大.被动吸烟是非吸烟者肺癌的危险因素(调整OR=1.912,95％CI:1.486～2.460),工作环境被动吸烟的男性非吸烟者患肺癌的调整OR为2.221(95％CI:1.361 ～3.625),家庭环境被动吸烟的女性非吸烟者患肺癌的调整OR为1.804(95％ CI:1.270～2.562).68.04％男性肺癌的发生可归因于吸烟,26.51％非吸烟者肺癌的发生可归因于被动吸烟.结论 吸烟是肺癌的重要危险因素,工作环境被动吸烟是男性非吸烟者肺癌的主要危险因素,家庭环境被动吸烟是女性肺癌的主要危险因素.戒烟具有重大的公共卫生学意义.     

Active and passive smoking during pregnancy and risk of central nervous system tumours in children

The effects of maternal active and passive smoking during pregnancy on childhood central nervous system (CNS) tumours were assessed in a population-based case-control study. The mothers of 244 children aged 0-15 years with CNS tumours and 502 control mothers were interviewed about their smoking habits. All families were resident in the region of Lombardy, Italy. Risk estimates were calculated by unconditional logistic regression, adjusted for age, sex and area of residence. Active smoking by the parents before pregnancy was not associated with increased risk of CNS tumours in the children. Active smoking by the mother during early pregnancy (approximately the first 5 weeks) was associated with a slightly increased risk of the child developing a CNS tumour (odds ratio [OR] 1.5 [95% CI 1.0, 2.3]). An increased risk of CNS tumours was found in the children of non-smoking mothers exposed regularly to tobacco smoke both in early pregnancy (OR 1.8 [95% CI 1.2, 2.6]) and in late pregnancy (OR 1.7 [95% CI 1.2, 2.5]). Although this study was retrospective, the results confirm our previous findings and suggest an association between the risk of developing CNS tumours in children and regular passive smoking by the mother during pregnancy.     

Poliovirus vaccination during pregnancy, maternal seroconversion to simian virus 40, and risk of childhood cancer

Before 1963, poliovirus vaccine produced in the United States was contaminated with simian virus 40 (SV40), which causes cancer in animals. To examine whether early-life SV40 infection can cause human cancer, the authors studied 54,796 children enrolled in the US-based Collaborative Perinatal Project (CPP) in 1959-1966, 52 of whom developed cancer by their eighth birthday. Those children whose mothers had received pre-1963 poliovirus vaccine during pregnancy (22.5% of the children) had an increased incidence of neural tumors (hazard ratio = 2.6, 95% confidence interval: 1.0, 6.7; 18 cases) and hematologic malignancies (hazard ratio = 2.8, 95% confidence interval: 1.2, 6.4; 22 cases). For 50 CPP children with cancer and 200 CPP control children, the authors tested paired maternal serum samples from pregnancy for SV40 antibodies using a virus-like particle enzyme immunoassay and a plaque neutralization assay. Overall, mothers exhibited infrequent, low-level SV40 antibody reactivity, and only six case mothers seroconverted by either assay. Using the two SV40 assays, maternal SV40 seroconversion during pregnancy was not consistently related to children's case/control status or mothers' receipt of pre-1963 vaccine. The authors conclude that an increased cancer risk in CPP children whose mothers received pre-1963 poliovirus vaccine was unlikely to have been due to SV40 infection transmitted from mothers to their children.     

孕期被动吸烟对妊娠并发症及妊娠结局的影响

目的了解孕期被动吸烟发生情况,并探讨其对妊娠并发症及结局的影响。方法选取2012年4月―2013年3月在我国15家医疗保健机构分娩的8926例单胎活产产妇作为研究对象,使用自制调查问卷收集孕期被动吸烟发生情况、妊娠并发症和结局等信息,采用单因素和多因素Logistic回归分析模型分析孕期被动吸烟对妊娠并发症及结局的影响。结果共1801例产妇在孕期经历被动吸烟。控制混杂因素后,孕期经历被动吸烟的产妇妊娠期糖尿病(gestational diabetes mellitus,GDM)的发生风险是非被动吸烟者的1.359倍(95%CI:1.146~1.612,P<0.001),胎膜早破的风险为1.290倍(95%CI:1.095~1.520,P=0.002),早产的风险为1.367倍(95%CI:1.155~1.619,P<0.001),娩出低出生体重儿的风险为1.341倍(95%CI:1.079~1.668,P=0.008)。与非被动吸烟者相比,平均每周被动吸烟天数≥4天者胎膜早破、早产和低出生体重儿的发生风险分别为非被动吸烟者的1.402倍(95%CI:1.104~1.780,P=0.006)、1.690倍(95%CI:1.339~2.132,P<0.001)和1.584倍(95%CI:1.172~2.141,P=0.023)。结论被调查产妇孕期被动吸烟率较高,孕期经历被动吸烟能够增加妊娠期糖尿病、胎膜早破、早产和低出生体重儿的发生风险。     

Maternal smoking, alcohol, and coffee use during pregnancy and son's risk of testicular cancer

It has been suggested that increased risk for testicular cancer occurring worldwide may be due to exposures during fetal development. Lifestyle or environmental exposures may be the most important predictors of risk. However, few studies have directly examined these exposures prospectively. The Child Health and Development Studies is a 40-year follow-up of 20,530 pregnancies occurring between 1959 and 1967. There were 20 cases of testicular cancer diagnosed through 2003 among sons with a maternal interview in early pregnancy. Cases were matched to three controls on birth year and race. Odds ratios and 95% confidence intervals were calculated with exact conditional logistic regression. Compared to controls, mothers of testicular cancer cases were more likely to drink alcohol (unadjusted odds ratio, 3.2; 95% confidence interval, 0.83-15.48 for above vs. below the median for controls) and less likely to drink coffee (unadjusted odds ratio, 0.19; 95% confidence interval, 0.02-1.02 for above vs. below the median). Case mothers were neither more nor less likely to smoke. Although low power may limit interpretation of negative results, the prospective design minimizes bias. In this cohort, maternal serum testosterone in pregnancy was previously reported to be lower in women who drank alcohol. Because populations with high testicular cancer risk also have lower maternal testosterone, we suggest that testosterone could play a role in explaining the higher risk of son's testicular cancer among mothers who drank alcohol during pregnancy.     

Lung cancer from passive smoking: hypothesis or convincing evidence?

Summary The epidemiological literature on passive smoking and lung cancer is reviewed and the well-known criteria for establishing a causal relationship are applied in order to determine what level of causal evidence currently exists. Three cohort studies and 12 case control studies are analysed. Of the prospective cohort studies, one contributes very little to our knowledge, one shows no risk increase and one results in a moderate risk increase of 1.74 for women married to heavy smokers. The last is the only study which has to be taken seriously, even when other considerations show that its results might be caused by chance, bias or confounding. None of the six case control studies yielding a positive relationship was conducted according to the state of art of epidemiological research, giving reasonable and sound evidence which cannot be explained by chance, bias, confounding or misclassification. Two studies contribute nothing to the evidence. None of the four case control studies yielding no risk change or a risk decrease can exclude the possibility that a causal relation exists. The epidemiological and toxicological evidence is discussed in the light of recent findings. The volume of accumulated data is conflicting and inconclusive. The observations on nonsmokers that have been made so far are compatible with either an increased risk from passive smoking or an absence of risk. Applying the criteria proposed by IARC there is a state of inadequate evidence. The available studies, while showing some evidence of association, do not exclude chance, bias or confounding. They provide, however, a serious hypothesis. Further studies are needed, if one wants to come to an adequate and scientifically sound conclusion concerning the question as to whether passive smoking causes lung cancer in man.     

母体孕期主动或被动吸烟与后代多指(趾)畸形的病例对照研究

目的 近年来,临床上所见多指（趾）畸形的患儿数量与日俱增。除了遗传因素外,母体怀孕期间自身行为和环境因素的影响也越显重要;然而,关于这些影响的流行病学数据十分匮乏。方法 采用以医院为基础、以患儿年龄配对的1∶2病例对照研究,对多指（趾）患儿与正常儿的母亲进行问卷调查。采用交互作用分析、协变量筛选和多元logistic回归分析探究母亲孕期吸烟（主动或被动）和后代多指（趾）畸形的危险因素关系。结果 研究对象共纳入病例组143例,对照组286例。孕妇在怀孕期间吸烟,显著增加后代多指（趾）畸形的发病风险（主动吸烟：OR=4.74,95% CI：1.43～15.65,P=0.011;被动吸烟：OR=2.42,95% CI：1.32～4.44,P=0.004）。调整混杂因素后,母亲孕期吸烟对后代多指（趾）畸形的影响仍显著存在（主动吸烟：aOR=7.27,95% CI：1.72～30.72,P=0.007;被动吸烟：aOR=2.41,95% CI：1.11～5.23,P=0.026）。结论 母亲孕期主动或被动吸烟是后代发生多指（趾）畸形的危险因素,显著增加其发病风险。     

Effect of passive smoking during pregnancy on selected perinatal parameters

A prospective study of 1004 consecutive deliveries was carried out to investigate the effect of passive smoking during pregnancy on a set of perinatal parameters. The data set was a cooperative study involving 11 Italian cities, distributed nationally. The study group was divided in three categories according to the mother's cigarette smoke exposure during pregnancy, ie, not smokers, passive smokers, direct smokers. Potential confounders, including paternal characteristics, were adjusted for by multiple linear regression analysis. A mean reduction of 16 g (p less than 0.07) in birthweight and a decrease in birth length of 0.05 cm (p less than 0.08) were found for each hour of antenatal passive smoke exposure. No or slight effects were reported for the other perinatal parameters considered.     

Prematurity and low birth weight: effects of active and passive smoking during pregnancy

Among the risk factors inevitably associated with low birthweights and premature births, tobacco remains the factor most often cited. From 1997 to 1998, a study was conducted in a Quebec City hospital centre in order to determine the prevalence of smoking among pregnant women as well as their exposure to passive smoking at home and at work. The percentage of women who smoke before pregnancy is 40.2%, while that of women who smoke during pregnancy is 37.3%. The analysis of characteristics of pregnant women who smoke and do not smoke shows strong variations according to age, education, matrimonial status and income. The relative risk linked to smoking is 1.54 for premature birth and 2.21 for low birthweight.     

Exposure to misoprostol and hormones during pregnancy and risk of congenital anomalies

This study evaluated the association between use of misoprostol and other drugs to induce menstruation, and congenital anomalies. A sample of 4,856 pregnant women 20 years and older were enrolled consecutively in prenatal services in the Unified National Health System, in six Brazilian State capitals. Data on socio-demographics and use of medicines were obtained using an interview from the 21st to 28th week of pregnancy. Other data, including information on delivery and diagnosis of congenital anomalies by the attending neonatal physician were obtained from patient charts. Potential confounders were adjusted by logistic regression. Use of drugs to induce menstruation was reported by 707 women (14.6%), of whom 120 (17%) reported use of misoprostol. After adjusting for the study center, a positive association was observed between misoprostol and congenital anomalies (OR = 2.64; 95% CI: 1.03-6.75); a positive association was also observed for sex hormones (OR = 2.24; 95% CI: 1.06-4.74). The results suggest that the use of misoprostol or sex hormones during pregnancy increases the risk of congenital anomalies.     

Preterm delivery and exposure to active and passive smoking during pregnancy: a case-control study from Italy

The aim of this study was to assess the relationship between preterm/early preterm delivery and active smoking as well as environmental tobacco smoke (ETS) exposure in a sample of pregnant Italian women. A case-control study was conducted in nine cities in Italy between October 1999 and September 2000. Cases of preterm birth were singleton babies born before the 37th gestational week; babies born before the 35th gestational week were considered early preterm births. Controls were babies with gestational ages >or= 37th week. A total of 299 preterm cases (including 105 early preterm) and 855 controls were analysed. A self-administered questionnaire was used to assess active smoking and ETS exposure, as well as potential confounders. Multivariable logistic regression analysis showed a relationship between active smoking during pregnancy and preterm/early preterm delivery [adjusted ORs: 1.53; 95% CI 1.05, 2.21 and 2.00; 95% CI 1.16, 3.45, respectively]. A dose-response relationship was found for the number of cigarettes smoked daily. The adjusted ORs were 1.54 and 1.69 for preterm babies and 1.90 and 2.46 for early preterm babies for 1-10 and >10 cigarettes/day respectively. ETS exposure was associated with early preterm delivery [adjusted OR 1.56; 95% CI 0.99, 2.46] with a dose-response relationship with the number of smokers in the home. Smoking during pregnancy was strongly associated with preterm delivery with a dose-response effect. ETS exposure in non-smoking women was associated only with early preterm delivery.     

Brassica vegetables and prostate cancer risk: a review of the epidemiological evidence

Epidemiological studies have yielded conflicting results on the associations of diet with prostate cancer. We review evidence that Brassica vegetables are associated with reduced prostate cancer risk. Brassica vegetables, which include broccoli, cabbage, mustard and collard greens, and bok choy, contain glucosinolates, the metabolic breakdown products of which are potent modulators of xenobiotic-metabolizing enzymes that protect DNA from damage. Twelve published studies give some information about Brassica vegetables and prostate cancer risk; six of these studies can be clearly interpreted. Of these, three reported statistically significant reduced risks (P < 0.05) and one reported a borderline significant reduced risk (P = 0.06) with high Brassica vegetable consumption. The epidemiological literature provides modest support for the hypothesis that high intakes of Brassica vegetables reduce prostate cancer risk.     

Does passive smoking in early pregnancy increase the risk of small-for-gestational-age infants?

OBJECTIVES: This study tested the hypothesis that women who deliver small-for-gestational-age infants are more often exposed to passive smoking at home or at work. METHODS: Among a 1-year cohort of nulliparous women in the city of Malmö, Sweden 872 (87.7%) women completed a questionnaire during their first prenatal visit. The study was carried out among women whose pregnancies resulted in a singleton live birth (n = 826), 6.7% of infants were classified as small for their gestational age. RESULTS: Passive smoking in early pregnancy was shown to double a woman''s risk of delivering a small-for-gestational-age infant, independent of potential confounding factors such as age, height, weight, nationality, educational level, and the mother''s own active smoking (odds ratio [OR] = 2.7). A stratified analysis indicated interactional effects of maternal smoking and passive smoking on relative small-for-gestational-age risk. CONCLUSIONS: Based on an attributable risk estimate, a considerable reduction in the incidence of small-for-gestational-age births could be reached if pregnant women were not exposed to passive smoking.