Maternal smoking during pregnancy and the risk of childhood brain tumors: Results from a Swedish cohort study

Maternal smoking, consumption of alcohol, and caffeinated beverages during pregnancy and the risk of childhood brain tumors: a meta-analysis of observational studies

BACKGROUND

We conducted this meta-analysis to investigate the potential association between maternal smoking, alcohol and caffeinated beverages consumption during pregnancy and the risk of childhood brain tumors (CBTs).

METHODS

A thorough search was carried out on PubMed, Embase, Web of Science, Cochrane Library, and China National Knowledge Internet to identify pertinent articles. Fixed or random effects model was applied to meta-analyze the data.

RESULTS

The results suggested a borderline statistically significant increased risk of CBTs associated with maternal smoking during pregnancy (OR 1.04, 95% CI 0.99-1.09). We found that passive smoking (OR 1.12, 95% CI 1.03-1.20), rather than active smoking (OR 1.00, 95% CI 0.93-1.07), led to an increased risk of CBTs. The results suggested a higher risk in 0-1 year old children (OR 1.21, 95% CI 0.94-1.56), followed by 0-4 years old children (OR 1.12, 95% CI 0.97-1.28) and 5-9 years old children (OR 1.11, 95% CI 0.95-1.29). This meta-analysis found no significant association between maternal alcohol consumption during pregnancy and CBTs risk (OR 1.00, 95% CI 0.80-1.24). An increased risk of CBTs was found to be associated with maternal consumption of caffeinated beverages (OR 1.16, 95% CI 1.07-1.26) during pregnancy, especially coffee (OR 1.18, 95% CI 1.00-1.38).

CONCLUSIONS

Maternal passive smoking, consumption of caffeinated beverages during pregnancy should be considered as risk factors for CBTs, especially glioma. More prospective cohort studies are warranted to provide a higher level of evidence.

Risk factors for childhood brain tumours: A systematic review and meta-analysis of observational studies from 1976 to 2022

BACKGROUND

Childhood brain tumours (CBTs) are the leading cause of cancer death in children under the age of 20 years globally. Though the aetiology of CBT remains poorly understood, it is thought to be multifactorial. We aimed to synthesize potential risk factors for CBT to inform primary prevention.

METHODS

We conducted a systematic review and meta-analysis of epidemiological studies indexed in the PubMed, Web of Science, and Embase databases from the start of those resources through 27 July 2023. We included data from case-control or cohort studies that reported effect estimates for each risk factor around the time of conception, during pregnancy and/or during post-natal period. Random effects meta-analysis was used to estimate summary effect sizes (ES) and 95% confidence intervals (CIs). We also quantified heterogeneity (I2) across studies.

FINDINGS

A total of 4040 studies were identified, of which 181 studies (85 case-control and 96 cohort studies) met our criteria for inclusion. Of all eligible studies, 50% (n = 91) were conducted in Europe, 32% (n = 57) in North America, 9% (n = 16) in Australia, 8% (n = 15) in Asia, 1% (n = 2) in South America, and none in Africa. We found associations for some modifiable risk factors including childhood domestic exposures to insecticides (ES 1.44, 95% CI 1.20-1.73) and herbicides (ES 2.38, 95% CI 1.31-4.33). Maternal domestic exposure to insecticides (ES 1.45, 95% CI 1.09-1.94), maternal consumption of cured meat (ES 1.51, 95% CI 1.05-2.17) and coffee ≥ 2 cups/day (ES 1.45, 95% 95% CI 1.07-1.95) during pregnancy, and maternal exposure to benzene (ES 2.22; 95% CI 1.01-4.88) before conception were associated with CBTs in case-control studies. Also, paternal occupational exposure to pesticides (ES 1.48, 95% CI 1.23-1.77) and benzene (ES 1.74, 95% CI 1.10-2.76) before conception and during pregnancy were associated in case-control studies and in combined analysis. On the other hand, assisted reproductive technology (ART) (ES 1.32, 95% CI 1.05-1.67), caesarean section (CS) (ES 1.12, 95% CI 1.01-1.25), paternal occupational exposure to paint before conception (ES 1.56, 95% CI 1.02-2.40) and maternal smoking > 10 cigarettes per day during pregnancy (ES 1.18, 95% CI 1.00-1.40) were associated with CBT in cohort studies. Maternal intake of vitamins and folic acid during pregnancy was inversely associated in cohort studies. Hormonal/infertility treatment, breastfeeding, child day-care attendance, maternal exposure to electric heated waterbed, tea and alcohol consumption during pregnancy were among those not associated with CBT in both case-control and cohort studies.

CONCLUSION

Our results should be interpreted with caution, especially as most associations between risk factors and CBT were discordant between cohort and case-control studies. At present, it is premature for any CBT to define specific primary prevention guidelines.

Risk factors for tumors or leukemia development in the first two years of life

OBJECTIVES

The objective of this study was to determine the incidence of neoplastic diseases and associated risk factors in the early stages of life.

METHODS

Data were retrospectively assessed in 730,000 live births between 2000 and 2019. The occurrence of tumors was monitored in the neonatal, infant (1-12 months), and toddler (13-24 months) periods. Risk factors were divided into demographic, internal, and environmental factors. The control group consisted of subjects in the same age category without oncological diseases.

RESULTS

A total of 452 neoplastic diseases were diagnosed in the study sample. In total, 24% (110/452) manifested during the neonatal period, 45% (203/452) in infants, and 31% (139/452) at the age of 13-24 months. Any genetic disease (OR 26.68; 95% CI 7.64-93.12) and medications used by the mother (OR 3.07; 95% CI 1.32-7.15) were identified as risk factors. Without adjustment for all factors, asphyxia in the first minute, a younger age of the mother, lower pregnancy, and the presence of a congenital defect manifested themselves as risk factors.

CONCLUSIONS

The highest risk factors for the development of early childhood tumors were identified as with medications used by the mother before or during pregnancy and genetic diseases.

Parental Age and Childhood Lymphoma and Solid Tumor Risk: A Literature Review and Meta-Analysis

BACKGROUND

Although advanced parental age has been definitively linked to pediatric acute lymphoblastic leukemia, studies of parental age and pediatric solid tumors have not reached firm conclusions. This analysis aimed to elucidate the relationship between parental age and pediatric solid tumors through meta-analysis of existing studies based in population registries.

METHODS

We searched Medline (PubMed) and Embase for registry-based studies of parental age and solid tumors through March 2022. We performed random-effects meta-analysis to estimate pooled effects and 95% confidence intervals (CIs). All statistical tests were 2-sided.

RESULTS

A total of 15 studies covering 10 childhood solid tumor types (30 323 cases and 3 499 934 controls) were included in this analysis. A 5-year increase in maternal age was associated with an increased risk of combined central nervous system tumors (odds ratio [OR] = 1.07, 95% CI = 1.04 to 1.10), ependymoma (OR = 1.19, 95% CI = 1.09 to 1.31), astrocytoma (OR = 1.10, 95% CI = 1.05 to 1.15), rhabdomyosarcoma (OR = 1.14, 95% CI = 1.03 to 1.25), and germ cell tumors (OR = 1.06, 95% CI = 1.00 to 1.12). A 5-year increase in paternal age was associated with an increased risk of non-Hodgkin lymphoma (OR = 1.06, 95% CI = 1.00 to 1.12).

CONCLUSIONS

This meta-analysis of registry-based analyses of parental age and childhood cancer supports the association between older maternal age and certain childhood solid cancers. There is also some evidence that paternal age may be associated with certain cancers such as non-Hodgkin lymphoma. However, as maternal and paternal age are highly correlated, disentangling potential independent causal effects of either factor will require large studies with extensive data on potential confounders.

Methylation marks of prenatal exposure to maternal smoking and risk of cancer in adulthood

BACKGROUND

Prenatal exposure to maternal smoking is detrimental to child health but its association with risk of cancer has seldom been investigated. Maternal smoking induces widespread and long-lasting DNA methylation changes, which we study here for association with risk of cancer in adulthood.

METHODS

Eight prospective case-control studies nested within the Melbourne Collaborative Cohort Study were used to assess associations between maternal-smoking-associated methylation marks in blood and risk of several cancers: breast (n = 406 cases), colorectal (n = 814), gastric (n = 166), kidney (n = 139), lung (n = 327), prostate (n = 847) and urothelial (n = 404) cancer and B-cell lymphoma (n = 426). We used conditional logistic regression models to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for associations between cancer and five methylation scores calculated as weighted averages for 568, 19, 15, 28 and 17 CpG sites. Models were adjusted for confounders, including personal smoking history (smoking status, pack-years, age at starting and quitting) and methylation scores for personal smoking.

RESULTS

All methylation scores for maternal smoking were strongly positively associated with risk of urothelial cancer. Risk estimates were only slightly attenuated after adjustment for smoking history, other potential confounders and methylation scores for personal smoking. Potential negative associations were observed with risk of lung cancer and B-cell lymphoma. No associations were observed for other cancers.

CONCLUSIONS

We found that methylation marks of prenatal exposure to maternal smoking are associated with increased risk of urothelial cancer. Our study demonstrates the potential for using DNA methylation to investigate the impact of early-life, unmeasured exposures on later-life cancer risk.

Sex-specific effects of in utero and adult tobacco smoke exposure

Tobacco smoke has harmful effects on a multiorgan level. Exposure to smoke, whether in utero or environmental, significantly increases susceptibility. This susceptibility has been identified to be divergent between males and females. However, there remains a distinct lack of thorough research into the relationship between sex and exposure to tobacco. Females tend to generate a more significant response than males during adulthood exposure. The intrauterine environment is meticulously controlled, and exposure to tobacco presents a significant factor that contributes to poor health outcomes and susceptibility later in life. Analysis of these effects in relation to the sex of the offspring is yet to be holistically reviewed and summarized. In this review, we will delineate the time-dependent relationship between tobacco smoke exposure and sex-specific disease susceptibility. We further outline possible biological mechanisms that may contribute to the identified pattern.

Effects of parental smoking and indoor tobacco smoke exposure on respiratory outcomes in children

The extensive literature has reported adverse effects on environmental tobacco smoke (ETS) on children's health. We aim to analyze associations of ETS with dry night cough, croup, pneumonia, and frequent common cold and to disentangle the effects of prenatal, infancy and childhood exposure by multilevel logistic regression. A cross-sectional study was conducted among 41,176 children aged 3-8 years in 8 major cities of China during 2010-2011, and obtained demographic information, smoke exposure information, and respiratory outcomes. Parents' smoking habit and indoor tobacco smoke odor were considered as two indicators of ETS. The prevalences of respiratory outcomes were 6.0% for croup, 9.5% for frequency common cold, 17.1% for dry night cough and 32.3% for pneumonia respectively in the study. The associations between respiratory outcomes and parental smoking were not obvious, while indoor tobacco smoke odor was clearly and strongly associated with most respiratory outcomes, with adjusted odds ratios ranging from 1.06 to 1.95. Both infancy and childhood exposure to tobacco smoke odor were independent risk factors, but infancy exposure had a higher risk. The results explore that ETS increased the risk of respiratory outcomes in children, highlighting the need for raising awareness about the detrimental effects of tobacco smoke exposure.

Maternal use of illicit drugs, tobacco or alcohol and the risk of childhood cancer before 6 years of age

BACKGROUND

Previous studies provide conflicting evidence of a link between maternal substance use and risk of childhood cancer.

METHODS

We analyzed a cohort of 785,438 newborns in Quebec (2006-2016). We identified infants whose mothers had problematic illicit drug, tobacco, or alcohol use before or during pregnancy. The primary outcomes were childhood hematopoietic cancer or solid tumors within 0-5 years of age. Using Cox proportional hazards models, we computed hazard ratios (HR) and 95% confidence intervals (CI) for the association between maternal substance use and childhood cancer, adjusted for potential confounders.

RESULTS

A total of 925 cases of cancer occurred during 3.5 million person-years of follow-up. Children exposed to any maternal substance use had marginally elevated cancer incidence rates compared with unexposed children (29.4 vs. 26.1 per 100,000 person-years). Maternal illicit drug use was associated with the risk of acute lymphoblastic leukemia (HR 1.63, 95% CI 0.79-3.36) and fibrosarcoma (HR 2.11, 95% CI 0.86-5.16). Maternal tobacco use was associated with acute myeloid leukemia (HR 2.01, 95% CI 0.72-5.60) and fibrosarcoma (HR 2.13, 95% CI 1.05-4.32), but a weak association with neuroblastoma (HR 1.21, 95% CI 0.61-2.40) and renal tumors (HR 1.14, 95% CI 0.42-3.13) also appeared to be present.

CONCLUSIONS

We found a potential association between maternal substance use and certain types of early childhood cancer. Although effects were modest, maternal substance use may contribute to some types of childhood cancer, especially leukemia and fibrosarcoma.

Smoking during pregnancy as a possible risk factor for pediatric neoplasms in the offspring: A population-based cohort study

OBJECTIVE

The aim of this study was to evaluate the association between maternal smoking during pregnancy and future risk of childhood neoplasm risk.

STUDY DESIGN

A population based cohort analysis comparing the risk for long-term childhood neoplasms in children born (1991-2014) to mothers that smoked during pregnancy vs. those that did not. Childhood neoplasms were pre-defined based on ICD-9 codes, as recorded in the hospital medical files. Children with congenital malformations and multiple gestations were excluded from the analysis. Kaplan-Meier survival curves were constructed to compare cumulative oncological morbidity over time. Cox proportional hazards model was used to control for confounders.

RESULTS

241,273 infants met the inclusion criteria; out of those 2841 were born to mothers that smoked during pregnancy. Offspring to smoking mothers had higher incidence of benign (OR 1.6, 95%CI 1.02-2.58; p value = .038) but not malignant tumors. Total cumulative neoplasm incidence was significantly higher in smoking women (Log Rank = 0.001) but no significant difference in the incidence of malignant tumors was noted (Log Rank = 0.834). In a Cox regression model controlling for maternal confounders; a history of maternal smoking during pregnancy remained independently associated only with increased risk for benign tumors (adjusted HR 2.5, 95%CI 1.57-3.83, p = .001).

CONCLUSION

Maternal smoking during pregnancy is associated with increased long-term risk for benign but not malignant tumors. This is important when counseling mothers regarding potential future risks and recommended lifestyle modifications. Despite this large population study with long follow-up, childhood malignancies are rare, and clarifying the possible association may require further studies.

Tobacco, alcohol and illicit drugs during pregnancy and risk of neuroblastoma: systematic review

OBJECTIVE

To determine whether prenatal and perinatal maternal consumption of alcohol, tobacco and/or illicit drugs is associated with risk of neuroblastoma.

DATA SOURCES

Medline and Embase (both from inception to February 2017), and reference lists of included studies.

STUDY SELECTION

To be eligible, a study had to be an original report including data on intake of alcohol, tobacco smoking and/or consumption of illicit drugs during pregnancy and risk of neuroblastoma in the child.

DATA EXTRACTION

From eligible studies, data study characteristics as well as effect measures and confounders were extracted. We assessed unadjusted and confounder-adjusted estimates, performed risk of bias analysis, constructed random-effects models and assessed heterogeneity.

RESULTS

We identified 14 case-control studies (1987-2016) involving a total of 3114 children with neuroblastoma. Meta-analysis of unadjusted estimates showed an association between alcohol (OR 1.26; 95% CI 1.07 to 1.49), tobacco (OR 1.22; 95% CI 1.04 to 1.44) and illicit drug consumption during pregnancy and risk of neuroblastoma during childhood, with illicit drug consumption showing the strongest association (OR 3.26; 95% CI 1.36 to 7.86). However, adjusted estimates were highly heterogeneous.

LIMITATIONS

All studies were at high risk of bias.

CONCLUSIONS

Smoking, alcohol or illicit drugs during pregnancy might play a role in the development of neuroblastoma. However, well-designed studies are needed to assess whether these exposures are causal and whether time period during pregnancy, dose or co-consumption of substances is critical.

TRIAL REGISTRATION NUMBER

Registration number CRD42016036165.

Parental smoking, maternal alcohol, coffee and tea consumption and the risk of childhood brain tumours: the ESTELLE and ESCALE studies (SFCE, France)

PURPOSE

To investigate whether parental smoking around the time of pregnancy or maternal consumption of beverages (alcohol, coffee, or tea) during pregnancy were associated with the risk of CBT.

METHODS

We pooled data from two French national population-based case-control studies with similar designs conducted in 2003-2004 and 2010-2011. The mothers of 510 CBT cases (directly recruited from the national childhood cancer register) and 3,102 controls aged under 15 years, frequency matched by age and gender, were interviewed through telephone, which included questions about prenatal parental smoking and maternal consumption of alcohol, coffee and tea. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using unconditional logistic regression, adjusted for age, sex and study of origin.

RESULTS

No association was seen between CBT and the mother smoking or drinking alcohol, coffee, or tea during the index pregnancy. The OR between CBT and paternal smoking in the year before birth (as reported by the mother) was 1.25 (95% CI 1.03, 1.52) with an OR of 1.09 (0.99, 1.19) for every 10 cigarettes per day (CPD) smoked. The association between paternal smoking and CBT appeared to be stronger in children diagnosed before the age of five years (OR 1.52, 95% CI 1.14, 2.02) and for astrocytoma (OR 1.86, 95% CI 1.26, 2.74).

CONCLUSION

We found some evidence of a weak association between paternal smoking in the year before the child's birth and CBT, especially astrocytomas. These findings need to be replicated in other samples, using similar classifications of tumour subtypes.