Association of allergic diseases and epilepsy with risk of glioma, meningioma and acoustic neuroma: results from the INTERPHONE international case-control study.

We investigated the association of allergic diseases and epilepsy with risk of brain tumours, in Interphone, a 13-country case-control study. Data were obtained from 2693 glioma cases, 2396 meningioma cases, and 1102 acoustic neuroma cases and their 6321 controls. Conditional logistic regression models were used to estimate pooled odds ratios (ORs) and their respective 95% confidence intervals (CIs), adjusted for education and time at interview. Reduced ORs were observed for glioma in relation to physician-diagnosed asthma (OR = 0.73; CI 0.58-0.92), hay fever (OR 0.72; CI 0.61-0.86), and eczema (OR 0.78, CI 0.64-0.94), but not for meningioma or acoustic neuroma. Previous diagnosis of epilepsy was associated with an increased OR for glioma (2.94; CI 1.87-4.63) and for meningioma (2.12; CI 1.27-3.56), but not for acoustic neuroma. This large-scale case-control study adds to the growing evidence that people with allergies have a lower risk of developing glioma, but not meningioma or acoustic neuroma. It also supports clinical observations of epilepsy prior to the diagnosis of glioma and meningioma.

Proximity to overhead power lines and childhood leukaemia: an international pooled analysis.

BACKGROUND: Although studies have consistently found an association between childhood leukaemia risk and magnetic fields, the associations between childhood leukaemia and distance to overhead power lines have been inconsistent. We pooled data from multiple studies to assess the association with distance and evaluate whether it is due to magnetic fields or other factors associated with distance from lines. METHODS: We present a pooled analysis combining individual-level data (29,049 cases and 68,231 controls) from 11 record-based studies. RESULTS: There was no material association between childhood leukaemia and distance to nearest overhead power line of any voltage. Among children living < 50 m from 200 + kV power lines, the adjusted odds ratio for childhood leukaemia was 1.33 (95% CI: 0.92-1.93). The odds ratio was higher among children diagnosed before age 5 years. There was no association with calculated magnetic fields. Odds ratios remained unchanged with adjustment for potential confounders. CONCLUSIONS: In this first comprehensive pooled analysis of childhood leukaemia and distance to power lines, we found a small and imprecise risk for residences < 50 m of 200 + kV lines that was not explained by high magnetic fields. Reasons for the increased risk, found in this and many other studies, remains to be elucidated.

Physical working conditions as covered in European monitoring questionnaires.

BACKGROUND: The prevalence of workers with demanding physical working conditions in the European work force remains high, and occupational physical exposures are considered important risk factors for musculoskeletal disorders (MSD), a major burden for both workers and society. Exposures to physical workloads are therefore part of the European nationwide surveys to monitor working conditions and health. An interesting question is to what extent the same domains, dimensions and items referring to the physical workloads are covered in the surveys. The purpose of this paper is to determine 1) which domains and dimensions of the physical workloads are monitored in surveys at the national level and the EU level and 2) the degree of European consensus among these surveys regarding coverage of individual domains and dimensions. METHOD: Items on physical workloads used in one European wide/Spanish and five other European nationwide work environment surveys were classified into the domains and dimensions they cover, using a taxonomy agreed upon among all participating partners. RESULTS: The taxonomy reveals that there is a modest overlap between the domains covered in the surveys, but when considering dimensions, the results indicate a lower agreement. The phrasing of items and answering categories differs between the surveys. Among the domains, the three domains covered by all surveys are "lifting, holding & carrying of loads/pushing & pulling of loads", "awkward body postures" and "vibrations". The three domains covered less well, that is only by three surveys or less, are "physical work effort", "working sitting", and "mixed exposure". CONCLUSIONS: This is the first thorough overview to evaluate the coverage of domains and dimensions of self-reported physical workloads in a selection of European nationwide surveys. We hope the overview will provide input to the revisions and updates of the individual countries' surveys in order to enhance coverage of relevant domains and dimensions in all surveys and to increase the informational value of the surveys.

The Intracranial Distribution of Gliomas in Relation to Exposure From Mobile Phones: Analyses From the INTERPHONE Study.

When investigating the association between brain tumors and use of mobile telephones, accurate data on tumor position are essential, due to the highly localized absorption of energy in the human brain from the radio-frequency fields emitted. We used a point process model to investigate this association using information that included tumor localization data from the INTERPHONE Study (Australia, Canada, Denmark, Finland, France, Germany, Israel, Italy, Japan, New Zealand, Norway, Sweden, and the United Kingdom). Our main analysis included 792 regular mobile phone users diagnosed with a glioma between 2000 and 2004. Similar to earlier results, we found a statistically significant association between the intracranial distribution of gliomas and the self-reported location of the phone. When we accounted for the preferred side of the head not being exclusively used for all mobile phone calls, the results were similar. The association was independent of the cumulative call time and cumulative number of calls. However, our model used reported side of mobile phone use, which is potentially influenced by recall bias. The point process method provides an alternative to previously used epidemiologic research designs when one is including localization in the investigation of brain tumors and mobile phone use.

Self-reported Occupational Skin Exposure and Risk of Physician-certified Long-term Sick Leave: A Prospective Study of the General Working Population of Norway.

Little is known about the contribution of occupational skin exposure as a risk factor for physician-certified long-term sick leave in the general working population of Norway. This study drew a cohort (n = 12,255; response at baseline 69.9%) randomly from the general population of Norway. Occupational skin exposure (in 2009) was measured based on 5 items. The outcome of interest was physician-certified long-term sick leave ≥ 16 days during 2010. Statistical adjustment for psychosocial and mechanical occupational exposures was performed. Long-term sick leave was predicted by occupational skin exposure to cleaning products (odds ratio (OR) 1.7; 95% confidence interval (95% CI) 1.1-2.5) and waste (OR 2.1; 95% CI 1.1-3.7) among men, and occupational skin exposure to water (OR 1.3; 95% CI 1.0-1.6) among women. The estimated population attributable risk for occupational skin exposure was 14.5%, which emphasizes its contribution as an important risk factor for long-term sick leave.

Occupational noise exposure and hearing: a systematic review.

PURPOSE: To give a systematic review of the development of noise-induced hearing loss (NIHL) in working life. METHODS: A literature search in MEDLINE, Embase, Web of Science, Scopus, and Health and Safety Abstracts, with appropriate keywords on noise in the workplace and health, revealed 22,413 articles which were screened by six researchers. A total of 698 articles were reviewed in full text and scored with a checklist, and 187 articles were found to be relevant and of sufficient quality for further analysis. RESULTS: Occupational noise exposure causes between 7 and 21 % of the hearing loss among workers, lowest in the industrialized countries, where the incidence is going down, and highest in the developing countries. It is difficult to distinguish between NIHL and age-related hearing loss at an individual level. Most of the hearing loss is age related. Men lose hearing more than women do. Heredity also plays a part. Socioeconomic position, ethnicity and other factors, such as smoking, high blood pressure, diabetes, vibration and chemical substances, may also affect hearing. The use of firearms may be harmful to hearing, whereas most other sources of leisure-time noise seem to be less important. Impulse noise seems to be more deleterious to hearing than continuous noise. Occupational groups at high risk of NIHL are the military, construction workers, agriculture and others with high noise exposure. CONCLUSION: The prevalence of NIHL is declining in most industrialized countries, probably due to preventive measures. Hearing loss is mainly related to increasing age.

CCDC26, CDKN2BAS, RTEL1 and TERT Polymorphisms in pediatric brain tumor susceptibility.

The role of genetic polymorphisms in pediatric brain tumor (PBT) etiology is poorly understood. We hypothesized that single nucleotide polymorphisms (SNPs) identified in genome-wide association studies (GWAS) on adult glioma would also be associated with PBT risk. The study is based on the Cefalo study, a population-based multicenter case-control study. Saliva DNA from 245 cases and 489 controls, aged 7-19 years at diagnosis/reference date, was extracted and genotyped for 29 SNPs reported by GWAS to be significantly associated with risk of adult glioma. Data were analyzed using unconditional logistic regression. Stratified analyses were performed for two histological subtypes: astrocytoma alone and the other tumor types combined. The results indicated that four SNPs, CDKN2BAS rs4977756 (p = 0.036), rs1412829 (p = 0.037), rs2157719 (p = 0.018) and rs1063192 (p = 0.021), were associated with an increased susceptibility to PBTs, whereas the TERT rs2736100 was associated with a decreased risk (p = 0.018). Moreover, the stratified analyses showed a decreased risk of astrocytoma associated with RTEL1 rs6089953, rs6010620 and rs2297440 (p trend = 0.022, p trend = 0.042, p trend = 0.029, respectively) as well as an increased risk of this subtype associated with RTEL1 rs4809324 (p trend = 0.033). In addition, SNPs rs10464870 and rs891835 in CCDC26 were associated with an increased risk of non-astrocytoma tumor subtypes (p trend = 0.009, p trend = 0.007, respectively). Our findings indicate that SNPs in CDKN2BAS, TERT, RTEL1 and CCDC26 may be associated with the risk of PBTs. Therefore, we suggest that pediatric and adult brain tumors might share common genetic risk factors and similar etiological pathways.

Testicular germ cell tumours and parental occupational exposure to pesticides: a register-based case-control study in the Nordic countries (NORD-TEST study).

OBJECTIVES: A potential impact of exposure to endocrine disruptors, including pesticides, during intrauterine life, has been hypothesised in testicular germ cell tumour (TGCT) aetiology, but exposure assessment is challenging. This large-scale registry-based case-control study aimed to investigate the association between parental occupational exposure to pesticides and TGCT risk in their sons. METHODS: Cases born in 1960 or onwards, aged between 14 and 49 years, and diagnosed between 1978 and 2013 in Denmark, Finland, Norway or Sweden, were identified from the respective nationwide cancer registries. Four controls per case were randomly selected from the general national populations, matched on year of birth. Information on parental occupation was collected through censuses or Pension Fund information and converted into a pesticide exposure index based on the Finnish National Job-Exposure Matrix. RESULTS: A total of 9569 cases and 32,028 controls were included. No overall associations were found for either maternal or paternal exposures and TGCT risk in their sons, with ORs of 0.83 (95% CI 0.56 to 1.23) and of 1.03 (0.92 to 1.14), respectively. Country-specific estimates and stratification by birth cohorts revealed some heterogeneity. Cryptorchidism, hypospadias and family history of testicular cancer were risk factors but adjustment did not change the main results. CONCLUSIONS: This is the largest study on prenatal exposure to pesticides and TGCT risk, overall providing no evidence of an association. Limitations to assess individual exposure in registry-based studies might have contributed to the null result.

Self-reported occupational exposure to chemical and physical factors and risk of skin problems: a 3-year follow-up study of the general working population of Norway.

Prospective studies on occupational dermatoses in the general working population are sparse. This study investigated prospectively the impact of self-reported occupational exposure to chemicals and physical factors on the risk of skin problems. The cohort comprised respondents drawn randomly from the general population in Norway, who were registered employed in 2006 and 2009 (n = 6,745). Indoor dry air (odds ratio (OR) 1.3; 95% confidence interval (95% CI) 1.1-1.6) was a significant baseline predictor of skin problems at follow-up, whereas exposure to cleaning products (OR 1.7; 95% CI 1.2-2.5), water (OR 1.4; 95% CI 1.1-1.9) and indoor dry air (OR 1.6; 95% CI 1.1-2.1) at both measurement time-points was significantly associated with skin problems. The population risk attributable to these factors was 16%. This study quantified the contribution of occupational exposure factors to skin problems in the general working population of Norway.

Work-related psychosocial and mechanical risk factors for neck/shoulder pain: a 3-year follow-up study of the general working population in Norway.

PURPOSE: This study examines the impact of work-related psychosocial and mechanical exposure on the development of neck/shoulder pain in the general working population. METHODS: A randomly drawn cohort from the general population in Norway aged 18-66 was followed up for 3 years (n = 12,550, response rate = 67 %). Eligible respondents were in paid work during the reference week in 2006 and 2009, or temporarily absent from such work (n = 6,745). Four work-related psychosocial factors and six mechanical exposures were measured. Outcomes of interest were moderate or severe neck/shoulder pain at follow-up adjusted for baseline neck/shoulder pain. RESULTS: In total, 16.9 % (1,138 individuals) reported neck/shoulder pain during the last month at follow-up. Work related psychosocial predictors of neck/shoulder pain were high job demands (highest OR 1.41, 95 % CI 1.11-1.78) and low levels of supportive leadership (highest OR 1.66, 95 % CI 1.08-2.54). Mechanical factors were neck flexion (highest OR 1.77, 95 % CI 1.31-2.39) and lifting in awkward postures (highest OR 1.81, 95 % CI 1.21-2.71). The estimated population risk attributable to these factors was about 23 %. The relative risk for neck/shoulder pain associated with psychosocial exposure was slightly influenced by adjustment for physical risk factors, and vice versa. There was no substantial confounding related to age, gender, education, occupation or psychological distress. CONCLUSIONS: Highly demanding jobs, neck flexion and awkward lifting appear as the most important predictors of neck/shoulder pain.

Psychosocial and organizational risk factors for doctor-certified sick leave: a prospective study of female health and social workers in Norway.

BACKGROUND: Doctor-certified sick leave differs substantially across sectors, and among health and social workers, in particular, there is an increased risk. Previous studies have shown that work environmental factors contribute to sick leave. Hence, the identification of specific organizational and psychosocial risk factors for long- term sick leave, taking into account potential confounding related to mechanical risk factors such as lifting and awkward body postures, will be of importance in the work of prevention. METHODS: A randomly drawn population sample of Norwegian residents was interviewed about working conditions in 2009 (n = 12,255; response rate 60.9%). Female health and social care workers (n = 925) were followed in a national registry for subsequent sickness absence during 2010. The outcome of interest was doctor-certified sick leave of 21 days or more (long-term sick leave). Eleven work-related psychosocial and organizational factors were evaluated. RESULTS: In total, 186 persons (20.1%) were classified with subsequent long-term sick leave. After thoroughly adjusting for competing explanatory variables, the most consistent predictors for long-term sick leave were violence and threats of violence (OR = 1.67; 95% CI 1.14-2.45). The estimated population attributable risk for violence and threats of violence was 13%. CONCLUSIONS: The present study among female health and social care workers revealed a substantial relationship between self-reported violence and threats of violence and subsequent long- term sick leave.

Dimensional comparability of psychosocial working conditions as covered in European monitoring questionnaires.

BACKGROUND: In most countries in the EU, national surveys are used to monitor working conditions and health. Since the development processes behind the various surveys are not necessarily theoretical, but certainly practical and political, the extent of similarity among the dimensions covered in these surveys has been unclear. Another interesting question is whether prominent models from scientific research on work and health are present in the surveys--bearing in mind that the primary focus of these surveys is on monitoring status and trends, not on mapping scientific models. Moreover, it is relevant to know which other scales and concepts not stemming from these models have been included in the surveys. The purpose of this paper is to determine (1) the similarity of dimensions covered in the surveys included and (2) the congruence of dimensions of scientific research and of dimensions present in the monitoring systems. METHOD: Items from surveys representing six European countries and one European wide survey were classified into the dimensions they cover, using a taxonomy agreed upon among all involved partners from the six countries. RESULTS: The classification reveals that there is a large overlap of dimensions, albeit not in the formulation of items, covered in the seven surveys. Among the available items, the two prominent work-stress-models--job-demand-control-support-model (DCS) and effort-reward-imbalance-model (ERI)--are covered in most surveys even though this has not been the primary aim in the compilation of these surveys. In addition, a large variety of items included in the surveillance systems are not part of these models and are--at least partly--used in nearly all surveys. These additional items reflect concepts such as "restructuring", "meaning of work", "emotional demands" and "offensive behaviour/violence & harassment". CONCLUSIONS: The overlap of the dimensions being covered in the various questionnaires indicates that the interests of the parties deciding on the questionnaires in the different countries overlap. The large number of dimensions measured in the questionnaires and not being part of the DCS and ERI models is striking. These "new" dimensions could inspire the research community to further investigate their possible health and labour market effects.

Work-related psychosocial and mechanical risk factors for low back pain: a 3-year follow-up study of the general working population in Norway.

AIMS: This study examines the impact of work-related psychosocial and mechanical exposure on the development of low back pain (LBP) in the general working population. METHODS: A randomly drawn cohort from the general population in Norway aged 18-66 years was followed up for 3 years (n=12 550, response rate at baseline=67%). Eligible respondents were in paid work during a reference week in 2006 and 2009, or temporarily absent from such work (n=6745). Five work-related psychosocial factors and seven mechanical exposures were measured. Outcomes of interest were moderate or severe LBP at follow-up adjusted for baseline LBP. RESULTS: In total, 12.8% (861 individuals) reported LBP during the last month at follow-up. Work-related psychosocial predictors of LBP were high job demands (OR 1.41, 95% CI 1.16 to 1.72) and low job control (OR 1.26, 95% CI 1.01 to 1.57). Mechanical factors were prolonged standing (OR 1.48, 95% CI 1.20 to 1.83), awkward lifting (OR 1.55, 95% CI 1.28 to 1.88) and squatting/kneeling (OR 1.29, 95% CI 1.04 to 1.61). The estimated population risk attributable to these factors was approximately 42%. The risk for LBP associated with psychosocial exposure was not influenced by adjustment for mechanical risk factors, and vice versa. There was no substantial confounding related to age, gender, education, occupation or psychological distress. CONCLUSIONS: Highly demanding jobs, prolonged standing and awkward lifting appear as the most consistent and important predictors of LBP.

Brain tumors in children and adolescents and exposure to animals and farm life: a multicenter case-control study (CEFALO).

OBJECTIVES: The etiology of brain tumors in children and adolescents is largely unknown, and very few environmental risk factors have been identified. The aim of this study was to examine the relationship between pre- or postnatal animal contacts or farm exposures and the risk of childhood brain tumors (CBTs), since infectious agents may pose a risk factor and a proposed mechanism is transferral of infectious agents from animals to humans. METHODS: The case-control study conducted in Denmark, Norway, Sweden, and Switzerland included brain tumor cases diagnosed from 2004 to 2008 aged 7-19 years at diagnosis. Three hundred and fifty-two cases (83 % participation rate) were matched to 646 population-based controls (71 % participation rate). Conditional logistic regression was used to estimate odds ratios. RESULTS: Maternal farm residence during pregnancy was inversely related to all CBTs combined (adjusted odds ratio (aOR) = 0.40, 95 % confidence interval (CI) = 0.19-0.88), as was the child's farm residence but not statistically significantly so (aOR = 0.57, 95 % CI = 0.28-1.17). Exposure to animals was in general not related to CBT risk except postnatal contact with birds showing reduced aORs of all CBTs (0.67, 95 % CI = 0.46-0.97) and primitive neuroectodermal tumor (0.28, 95 % CI = 0.10-0.83). Sensitivity analyses focusing on early exposure of the child did not change the associations observed for the entire exposure period with the exception of exposure to goats and sheep which was associated with reduced risks of both all CBTs (aOR = 0.48, 95 % CI = 0.24-0.97) and astrocytomas (aOR = 0.29, 95 % CI = 0.10-0.87). CONCLUSION: Altogether, our data indicate an inverse association between the mother during pregnancy or the child living on a farm and CBT risk, which contrasts with the existing literature and merits further attention. With respect to exposure to animals, we did not observe any systematic pattern. This suggests that a potential protective effect of farm residence is mediated by some other factor than animal contact.

Diagnostic radiological examinations and risk of intracranial tumours in adults-findings from the Interphone Study.

BACKGROUND: Exposure to high doses of ionizing radiation is among the few well-established brain tumour risk factors. We used data from the Interphone study to evaluate the effects of exposure to low-dose radiation from diagnostic radiological examinations on glioma, meningioma and acoustic neuroma risk. METHODS: Brain tumour cases (2644 gliomas, 2236 meningiomas, 1083 neuromas) diagnosed in 2000-02 were identified through hospitals in 13 countries, and 6068 controls (population-based controls in most centres) were included in the analysis. Participation across all centres was 64% for glioma cases, 78% for meningioma cases, 82% for acoustic neuroma cases and 53% for controls. Information on previous diagnostic radiological examinations was obtained by interviews, including the frequency, timing and indication for the examinations. Typical brain doses per type of examination were estimated based on the literature. Examinations within the 5 years before the index date were excluded from the dose estimation. Adjusted odds ratios were estimated using conditional logistic regression. RESULTS: No materially or consistently increased odds ratios for glioma, meningioma or acoustic neuroma were found for any specific type of examination, including computed tomography of the head and cerebral angiography. The only indication of an elevated risk was an increasing trend in risk of meningioma with the number of isotope scans, but no such trends for other examinations were observed. No gradient was found in risk with estimated brain dose. Age at exposure did not substantially modify the findings. Sensitivity analyses gave results consistent with the main analysis. CONCLUSIONS: There was no consistent evidence for increased risks of brain tumours with X-ray examinations, although error from selection and recall bias cannot be completely excluded. A cautious interpretation is warranted for the observed association between isotope scans and meningioma.

Location of gliomas in relation to mobile telephone use: a case-case and case-specular analysis.

The energy absorbed from the radio-frequency fields of mobile telephones depends strongly on distance from the source. The authors' objective in this study was to evaluate whether gliomas occur preferentially in the areas of the brain having the highest radio-frequency exposure. The authors used 2 approaches: In a case-case analysis, tumor locations were compared with varying exposure levels; in a case-specular analysis, a hypothetical reference location was assigned for each glioma, and the distances from the actual and specular locations to the handset were compared. The study included 888 gliomas from 7 European countries (2000-2004), with tumor midpoints defined on a 3-dimensional grid based on radiologic images. The case-case analyses were carried out using unconditional logistic regression, whereas in the case-specular analysis, conditional logistic regression was used. In the case-case analyses, tumors were located closest to the source of exposure among never-regular and contralateral users, but not statistically significantly. In the case-specular analysis, the mean distances between exposure source and location were similar for cases and speculars. These results do not suggest that gliomas in mobile phone users are preferentially located in the parts of the brain with the highest radio-frequency fields from mobile phones.

Impact of random and systematic recall errors and selection bias in case--control studies on mobile phone use and brain tumors in adolescents (CEFALO study).

Whether the use of mobile phones is a risk factor for brain tumors in adolescents is currently being studied. Case--control studies investigating this possible relationship are prone to recall error and selection bias. We assessed the potential impact of random and systematic recall error and selection bias on odds ratios (ORs) by performing simulations based on real data from an ongoing case--control study of mobile phones and brain tumor risk in children and adolescents (CEFALO study). Simulations were conducted for two mobile phone exposure categories: regular and heavy use. Our choice of levels of recall error was guided by a validation study that compared objective network operator data with the self-reported amount of mobile phone use in CEFALO. In our validation study, cases overestimated their number of calls by 9% on average and controls by 34%. Cases also overestimated their duration of calls by 52% on average and controls by 163%. The participation rates in CEFALO were 83% for cases and 71% for controls. In a variety of scenarios, the combined impact of recall error and selection bias on the estimated ORs was complex. These simulations are useful for the interpretation of previous case-control studies on brain tumor and mobile phone use in adults as well as for the interpretation of future studies on adolescents.

Exposure to loud noise and risk of vestibular schwannoma: results from the INTERPHONE international case‒control study.

Objective Studies of loud noise exposure and vestibular schwannomas (VS) have shown conflicting results. The population-based INTERPHONE case‒control study was conducted in 13 countries during 2000-2004. In this paper, we report the results of analyses on the association between VS and self-reported loud noise exposure. Methods Self-reported noise exposure was analyzed in 1024 VS cases and 1984 matched controls. Life-long noise exposure was estimated through detailed questions. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using adjusted conditional logistic regression for matched sets. Results The OR for total work and leisure noise exposure was 1.6 (95% CI 1.4-1.9). OR were 1.5 (95% CI 1.3-1.9) for only occupational noise, 1.9 (95% CI 1.4-2.6) for only leisure noise and 1.7 (95% CI 1.2-2.2) for exposure in both contexts. OR increased slightly with increasing lag-time. For occupational exposures, duration, time since exposure start and a metric combining lifetime duration and weekly exposure showed significant trends of increasing risk with increasing exposure. OR did not differ markedly by source or other characteristics of noise. Conclusion The consistent associations seen are likely to reflect either recall bias or a causal association, or potentially indicate a mixture of both.

Reproductive factors and risk of meningioma and glioma.

Female sex hormones have previously been suggested as possible risk factors for brain tumors, but published studies have reported conflicting results. We conducted a population-based case-control study of glioma (n=626) and meningioma (n=906) cases and randomly selected controls stratified on age and geographic region (n=1,774) in Denmark, Finland, Norway, Sweden, and the United Kingdom. Unconditional logistic regression was used to estimate odds ratios (OR) for glioma and meningioma in relation to reproductive factors. A decreased glioma risk was associated with ever-pregnancy compared with never-pregnancy [OR, 0.8; 95% confidence interval (95% CI), 0.6-1.0]. Meningioma risk among women ages <50 years was increased in relation to number of pregnancies leading to a live birth (OR, 1.8; 95% CI: 1.1-2.8 for giving birth to 3 children compared with nulliparous women; P(trend) among parous women=0.01). This relation was not found for older women. Breast-feeding among parous women increased the glioma risk (OR, 2.2; 95% CI, 1.3-3.9 for breast-feeding 36 months or more compared with breast-feeding 3 months or less). Menopausal status and age at menopause were not associated with meningioma or glioma risk. Our findings imply that reproductive hormones may influence the occurrence of meningioma and glioma.