Parental Smoking Habits Research Articles

Determinants of Smoking Habit among Medical Students.

A cross sectional study of smoking habits among medical students was carried out to find out the prevalence of smoking and its association with certain factors such as parental smoking, peer pressure, use of alcohol and other drugs. Prevalence of smoking was 46%. There was significant association of smoking with parental smoking habit, peer pressure, use of alcohol and other drugs. Strategies to counter these social determinants have been discussed.

Tabaquismo pasivo prenatal y posnatal y bronquiolitis

To determine the influence of pre- and postnatal tobacco exposure in the development of bronchiolitis. A questionnaire was given to the parents of children hospitalized between August 2001 and August 2002. It included items on parental smoking habits and maternal smoking during pregnancy. Clinical, analytical and radiological criteria were used to diagnose bronchiolitis. Of 450 children, 123 (27.3 %) were diagnosed with bronchiolitis. The control group was composed of 327 children. A total of 61.6 % of the children had at least one parent who smoked and 32.9 % of these children developed bronchiolitis; 39.1 % had non-smoking parents and 18.2 % were hospitalized with bronchiolitis (OR 2.20 [1.39-3.47]). Of the entire group of children studied, 35.3 % had mothers who smoked and 37.7 % of these children had bronchiolitis compared with 21.4 % of children whose mothers were non-smokers (OR 2.22 [1.45-3.39]). A total of 49.6 % had fathers who smoked, and 32.3 % of these children were diagnosed with bronchiolitis compared with 22 % of children whose fathers were non-smokers (OR 1.65 [1.10-2.57]). Forty-four percent of children whose mothers smoked during pregnancy were hospitalized with bronchiolitis compared with only 20.9 % of non-exposed children (OR 2.96 [1.90-4.62]). The large number of mothers who smoked during pregnancy (27.8 %) was notable. Multivariant analysis with logistic regression was performed and the only variable that remained statistically significant was smoking during pregnancy (p < 0.00001; OR 3.27 [1.39-7.71]). Maternal smoking during pregnancy seems to be the main risk factor for the subsequent development of bronchiolitis

Helicobacter pylori seropositivity among adolescents in Novosibirsk, Russia: prevalence and associated factors.

We have reported previously that infection is widespread among adults in Siberia, in whom prevalence rates range from 70% to 90%. The present study was undertaken to determine the seroprevalence of infection and its relation to social factors in a community-based population of adolescents in Novosibirsk, Western Siberia. All students in forms 9 to 11 of four randomly selected secondary schools participated. A total of 423 students (180 boys, 243 girls; age, 14-17 years) completed structured questionnaire concerning their lifestyle, and sera were tested for using enzyme-linked immunosorbent assay (Pyloriset -New EIA-G; Orion Diagnostica, Finland). Personal information, including parental history, educational level, occupation, and smoking habits, were collected via a questionnaire. Overall, the seroprevalence of infection was 56.3%. Age, sex, smoking, alcohol consumption, number of children and pets in the household, and family history of gastric diseases were not associated with positivity. The predictors of infection were dwelling without running hot water supply and sewage (odds ratio [OR] = 2.4; 95% confidence interval [CI], 1.2-4.8), father's occupation as a manual worker (OR = 2.7; 95% CI, 1.5-5.0), mother's occupation as a manual worker (OR = 1.8; 95% CI, 1.0-3.0), father's lower educational attainment (OR = 2.1; 95% CI, 1.2-3.6), and father's smoking (OR = 1.8; 95% CI, 1.1-3.2). The prevalence of seropositivity among adolescents in Russia is higher than in developed countries. The infection is associated with lower socioeconomic status.

Helicobacter pylori Seropositivity among Adolescents in Novosibirsk, Russia: Prevalence and Associated Factors

ABSTRACTObjectivesWe have reported previously that Helicobacter pylori infection is widespread among adults in Siberia, in whom prevalence rates range from 70% to 90%. The present study was undertaken to determine the seroprevalence of H. pylori infection and its relation to social factors in a community‐based population of adolescents in Novosibirsk, Western Siberia.MethodsAll students in forms 9 to 11 of four randomly selected secondary schools participated. A total of 423 students (180 boys, 243 girls; age, 14–17 years) completed structured questionnaire concerning their lifestyle, and sera were tested for H. pylori using enzyme‐linked immunosorbent assay (Pyloriset®–New EIA‐G; Orion Diagnostica, Finland). Personal information, including parental history, educational level, occupation, and smoking habits, were collected via a questionnaire.ResultsOverall, the seroprevalence of H. pylori infection was 56.3%. Age, sex, smoking, alcohol consumption, number of children and pets in the household, and family history of gastric diseases were not associated with H. pylori positivity. The predictors of infection were dwelling without running hot water supply and sewage (odds ratio [OR] = 2.4; 95% confidence interval [CI], 1.2–4.8), father's occupation as a manual worker (OR = 2.7; 95% CI, 1.5–5.0), mother's occupation as a manual worker (OR = 1.8; 95% CI, 1.0–3.0), father's lower educational attainment (OR = 2.1; 95% CI, 1.2–3.6), and father's smoking (OR = 1.8; 95% CI, 1.1–3.2).ConclusionsThe prevalence of H. pylori seropositivity among adolescents in Russia is higher than in developed countries. The infection is associated with lower socioeconomic status.

Factores de riesgo coronario en la adolescencia. Estudio FRICELA

In a grou of adolescents, to examine the prevalence of behaviors and risk factors that predispose to coronary heart disease and ascertain their associations. A population of 2,599 adolescents, age 12 to 19 years, both sexes, was studied. The study sites were 30 public or private medical centers located in the Federal District and 12 provinces of Argentina. Teenagers with hypercholesterolemia had a greater body mass index, higher incidence of hypertension, and more frequent sedentary lifestyle. There was a positive correlation between hypertension, body mass index, and family history of hypertension, and a negative correlation with physical exercise. Obesity in the young correlated with obesity in their parents. At the age of 19 years, 42% consumed alcohol and 28% smoked. The association between smoking and alcohol consumption was very high (p < 0.0001). The smoking habits of parents strongly influenced their children. Early inculcation of a healthy lifestyle, consisting of regular physical exrcise, a healthy diet, and no smoking, could be the most important behavorial and risk factor interventions in the effort to curtail atherosclerosis in adults.

Early Rather than Recent Exposure to Tobacco Increases Bronchial Reactivity

Tobacco is well known to impair respiratory function of infants and children. This study was done to identify periods of increased vulnerability of the airways to tobacco products. In 162 unselected schoolchildren maximum expiratory flow at 25 % of vital capacity (MEF25) was measured before and after cold air hyperventilation. Parental smoking habits were assessed by measurement of cotinine concentrations in children's urine and by interview. Children, whose mothers had smoked during pregnancy, showed increased bronchial reactivity at school age compared to children whose mothers had not smoked during pregnancy (median MEF25 [25th, 75th percentile] after cold air challenge as percent of baseline: 83 % [76, 95] vs. 95 % [79, 100]; p = 0.03). Similar differences were found, when the study population was divided according to the maternal smoking status during the first six months of life. On the contrary, if the cotinine excretion exceeded the group median as a measure of recent exposure to tobacco smoke, bronchial reactivity was not increased (median MEF25 [25th, 75th percentile] as percent of baseline: 88 % [76, 100] vs. 93 % [79, 100]; p = 0.25). Pregnancy and early infancy were found to be periods of increased vulnerability of the airways to tobacco products.

Effectiveness of the PREVASC-intervention on reducing allergen and enwironmental tabacco smoke exposure

In the PREVASC-study, the effectiveness of a combined intervention program aimed at reducing the exposure to allergens and environmental tobacco smoke (ETS) on primary prevention of asthma in familial predisposed children, is being evaluated. Four hundred forty-one children will be followed from the prenatal period until the age of 6 years. The children are randomly allocated to an intervention group (n=222) or a usual care group (n=219). The parents in the intervention group are advised on measures to decrease the exposure of their child to allergens and ETS. The advice given is focussed on type of feeding in the first 6 months of life, ETS-exposure and exposure to house dust mite and pet allergens. Preliminary results of the exposure levels of the children participating in our study reveal that the intervention is very successful in reducing the allergen exposure but not exposure to ETS. Room for improvement on ETS exposure as measured by reported smoking habits of parents inside the house showed to be low. Only 15,3% of parents in the intervention group and 13,9% in the control group reported to be smokers (p=0.299). Exposure to house dust mite, cat- and dog allergen in the intervention group was reduced significantly (p=0.000). As far as the type of feeding is concerned, the results reveal that the intervention has resulted in a lower percentage of children exposed to cow's milk in the period from birth until 6 months of age. Twenty three % of children in the control group as compared to 57% in the intervention group were never exposed to cow's milk in the first 26 weeks of life (p=0.000). It is hypothesised that reducing the levels of exposure to allergens in early life will contribute to primary prevention of asthma in familial predisposed children.

Breast-feeding and its relation to smoking and mode of delivery

OBJECTIVE: To examine the effects of cesarean and forceps or vacuum delivery and parental smoking habits on the initiation and duration of breast-feeding. METHODS: We conducted a prospective, population-based birth cohort study in 1997. Data were collected on breast-feeding history, household smoking habits, method of delivery, and other demographic, obstetric, behavioral, and potential confounding variables via a standardized self-administered questionnaire. Multivariable logistic regression was used to examine the association between method of birth (cesarean versus forceps or vacuum delivery versus normal vaginal birth) and either not initiating breast-feeding or doing so for less than 1 month. Among women who breast-fed for 1 month or more, multivariable survival analysis was employed to study the relationship between method of delivery and breast-feeding duration. We repeated these analyses to examine the link between parental smoking habits and breast-feeding initiation and duration. RESULTS: A total of 7825 mother-infant pairs were followed up for 9 months. Cesarean delivery was a risk factor for not initiating breast-feeding, for breast-feeding less than 1 month, and remained a significant hazard against breast-feeding duration. Assisted delivery with forceps or vacuum, although not associated with breast-feeding initiation, was a significant risk against breast-feeding duration. Conversely, current parental smoking habits only affected breast-feeding initiation but were unrelated to breast-feeding duration. CONCLUSION: This study indicates a possible effect of forceps or vacuum delivery on breast-feeding and of cesarean on long-term breast-feeding duration. The findings provide additional evidence in support of the avoidance of unnecessary obstetric interventions.

Parental periconceptional smoking and male: female ratio of newborn infants

We assessed whether the smoking habits of parents around the time of conception affects the likelihood of the offspring being male or female. We found that the offspring sex ratio (male to female) was lower when either one or both of the parents smoked more than 20 cigarettes per day compared with couples in which neither of the parents smoked. We found the lowest sex ratio among children whose mothers and fathers both smoked more than 20 cigarettes per day (p<0.0001). Parental periconceptional smoking might be a contributing factor to a lower male to female sex ratio of offspring.

Acute respiratory infection among children in an air force community

984 children of 745 families were studied for occurrence of Acute Respiratory Infection (ARI). Incidence of ARI was 3.5 episodes per year among infants and 1.8 episodes per child per year among under-five children. 88.8% episodes of ARI were mild while 11.2% episodes were moderate to severe, which mostly occurred in winter. Parental smoking habit, decline in duration of breast feeding, bedroom smoke pollution and over crowding were found to increase the risk of ARI among children. An effective preventive strategy has been highlighted.

Siblings, multiple births, and the incidence of allergic disease: a birth cohort study using the West Midlands general practice research database

BACKGROUNDThe presence of older siblings reduces the risk of developing hay fever, eczema and atopy, but findings for asthma have been inconsistent. Whether twins have a reduced risk of allergic...

Epidemiology of bronchial asthma and chronic rhinitis in schoolchildren of different ethnic origins from two neighboring towns in Israel

Allergic diseases have increased significantly in developed countries for reasons yet to be determined. We studied the epidemiology of bronchial asthma (B.A.) and chronic rhinitis (Ch.R.) among Israeli school children from two neighboring towns, one Jewish (Zichron Yaakov, school population = 585) and the other Arab (Paradis, school population = 658). The children (age range 8-17 years, 567 males, 676 females) shared the same climate and had similar demographic characteristics. They received similar medical care and had the same rates of hospitalization and emergency room visits. The Jewish children had a higher prevalence of B.A. (13.7% vs. 9.4%), Ch.R. (19.7% vs. 9.7%), and stuffy nose (31% vs. 14%) than their Arab counterparts. In addition to ethnicity, parental smoking habits were the major differentiating factor between the two groups: 20% of the mothers and 29% of the fathers from Zichron Yaakov and 2% of the mothers and 60% of the fathers from Paradis were smokers. Smoking fathers increased the rate of B.A. in both towns as well as emergency room visits, but not the rate of Ch.R. or stuffy nose. A familial history of B.A. was the main determinant for having childhood asthma or chronic rhinitis. We conclude that in addition to family history and ethnicity, smoking among mothers was the major contributing factor for the higher prevalence of atopic diseases among Jewish schoolchildren compared to their Arab counterparts.

Childhood cancer and parental use of tobacco: findings from the inter-regional epidemiological study of childhood cancer (IRESCC).

Parental smoking data have been re-abstracted from the interview records of the Inter-Regional Epidemiological Study of Childhood Cancer (IRESCC) to test further the hypothesis that paternal cigarette smoking is a risk factor for the generality of childhood cancer. Reported cigarette smoking habits for the parents of 555 children diagnosed with cancer in the period 1980–1983 were compared, in two separate matched pairs analyses, with similar information for the parents of 555 children selected from GP lists (GP controls) and for the parents of 555 hospitalized children (hospital controls). When cases were compared with GP controls there was a statistically significant positive trend (P = 0.02) between the risk of childhood cancer and paternal daily consumption of cigarettes before the pregnancy; there was no significant trend for maternal smoking habit. When cases were compared with hospital controls there was a statistically significant negative trend (P< 0.001) between the risk of childhood cancer and maternal daily consumption of cigarettes before the pregnancy; there was no significant trend for paternal smoking habit. Neither of the significant trends could be explained by adjustment for socioeconomic grouping, ethnic origin or parental age at the birth of the child, or by simultaneous analysis of parental smoking habits. Relations between maternal consumption of cigarettes and birth weights suggested that (maternal) smoking data were equally reliable for case and control subjects, although comparisons with national data suggested that the hospital control parents were unusually heavy smokers. These findings give some support for the hypothesis that paternal cigarette smoking is a potential risk factor for the generality of childhood cancers. © 2001 Cancer Research Campaign http://www. bjcancer.com

Re: Management of simple reflux and infant sleep positions

There was an insert in the September/October 1998 issue of Paediatr Child Health. The insert does not have page numbers, but is published in a striking colour and has the title “Simple reflux in infants”. The phraseology used in recommendations on infant positions for the treatment of simple reflux is potentially misleading. There have been major reductions in the incidence of sudden infant death syndrome (SIDS). There is strong evidence that this is due to a change in child care practices and a marked reduction in the number of infants who sleep in the prone position. For example, in Alberta, the SIDS rate has dropped from 1.87 in 1977 to 0.89 in 1995. Further reductions may be possible with rigorous adherence to supine positioning, and the avoidance of side as well as prone positions. It should be acknowledged that further reductions will require other changes, such as a change in the smoking habits of parents. In addition, SIDS remains uncommon and individual primary health care practitioners may never be involved in a case. Gastroesophageal reflux is common, and, as pointed out in the report, may cause more anxiety for parents than for physicians. Thus, symptomatic measures are important, but the adoption of the prone position for simple reflux puts infants younger than five months of age at increased risk of SIDS. This may add to other risk factors such as prematurity or parental smoking. Such a recommendation to change the sleep position of an infant should not be made lightly. Parents should be fully informed about the risks involved. Parents should also be informed that the risk of death due to aspiration is infinitesimal. For severe or complicated reflux, physician recommendations may include the prone or lateral position, but again parents should be counselled about the risk involved. Also, such patients should have a full assessment by a specialist. In general, measures to treat severe reflux other than the prone position should be tried first. The prone position should only be considered essential after a full investigation. Even then, the physician should explore other risk factors for SIDS and advise parents carefully about all the risks involved. It should be emphasized that whatever the sleeping position, children should have play activities in every position.

Toxigenic bacteria and sudden infant death syndrome (SIDS): nasopharyngeal flora during the first year of life.

Many developmental and environmental risk factors for sudden infant death syndrome (SIDS) are similar to those for susceptibility to respiratory tract infection, and toxigenic bacteria have been implicated in some SIDS cases. We assessed nasopharyngeal flora of healthy infants in relation to risk factors to determine which species best lit the mathematical model proposed for the common bacterial toxin hypothesis and if these findings complemented results obtained from SIDS cases which occurred during the period of the survey. Longitudinal studies were carried out between April 1993 and March 1996 on 253 healthy infants and their mothers. 150 from a multiply deprived area, 103 from an affluent area. Concurrent SIDS infants (37) were screened for nasopharyngeal flora. Among healthy infants < or = 3 months of age, the predominant isolate was Staphylococcus aureus 57% compared with 86% for SIDS infants in that age range (P< 0.02). There were significant associations between isolation of different species from both mother and baby but no association between isolation of any species with: area of residence: parental smoking habits; breast or bottle feeding; symptoms of viral infection: seasonality. We conclude that S. aureus fits the mathematical model for SIDS. Both staphylococci and/or their toxins were identified in a significant proportion of SIDS cases. Isolation of staphylococci from healthy infants was associated with the 2-4-month age range, a risk factor consistently found in all epidemiological studies of SIDS. This might reflect the developmental stage in which 80-90% of infants express the Lewis(a) antigen which we have shown to be one of the receptors for S. aureus.

Toxigenic bacteria and sudden infant death syndrome (SIDS): nasopharyngeal flora during the first year of life

Many developmental and environmental risk factors for sudden infant death syndrome (SIDS) are similar to those for susceptibility to respiratory tract infection, and toxigenic bacteria have been implicated in some SIDS cases. We assessed nasopharyngeal flora of healthy infants in relation to risk factors to determine which species best fit the mathematical model proposed for the common bacterial toxin hypothesis and if these findings complemented results obtained from SIDS cases which occurred during the period of the survey. Longitudinal studies were carried out between April 1993 and March 1996 on 253 healthy infants and their mothers, 150 from a multiply deprived area, 103 from an affluent area. Concurrent SIDS infants (37) were screened for nasopharyngeal flora. Among healthy infants ≤3 months of age, the predominant isolate was Staphylococcus aureus, 57% compared with 86% for SIDS infants in that age range ( P<0.02). There were significant associations between isolation of different species from both mother and baby but no association between isolation of any species with: area of residence; parental smoking habits; breast or bottle feeding; symptoms of viral infection; seasonality. We conclude that S. aureus fits the mathematical model for SIDS. Both staphylococci and/or their toxins were identified in a significant proportion of SIDS cases. Isolation of staphylococci from healthy infants was associated with the 2–4-month age range, a risk factor consistently found in all epidemiological studies of SIDS. This might reflect the developmental stage in which 80–90% of infants express the Lewis a antigen which we have shown to be one of the receptors for S. aureus.

The relative importance of socio-economic status, parental smoking and air pollution (SO2) on asthma symptoms, spirometry and bronchodilator response in 11-year-old children.

The aim of this study was to evaluate the relative contribution of several risk factors to the prevalence of allergic respiratory symptoms, and the positivity of the bronchodilator test with fenoterol, and to establish the relative importance of these factors on the variability of FVC, FEV1, PEF, MEF25, MEF50 and MEF75. A total of 340 11-year-old children attending school in polluted and non-polluted areas of the city of Cartagena, Spain, were studied. The polluted area had had an annual mean of 75 microg/m3 of SO2 over the last 10 years and the non-polluted area had < 20 microg/m3 during this period. A questionnaire about allergic respiratory symptoms was completed by the parents. Specific questions about parental smoking habits and socio-economic level were included. Each child's performance in spirometry before and after administration of 0.2 mg of inhaled fenoterol was evaluated. The only significant predictive variables in the logistic regression (for suffering any symptom or a positive bronchodilator response) were male sex for nasal symptoms (RR 1.37; p = 0.04) and housing near heavy traffic for eye symptoms (RR 1.45; p = 0.01). Living in the polluted area reduced the risk of a positive bronchodilator response (RR 0.61; p = 0.004). Maternal smoking, even though not statistically significant, tended to increased the risk of suffering any symptom (RR 1.26; p = 0.07) or of having a positive bronchodilator response (RR 1.23; p = 0.1). None of the risk factors studied was of significant importance in explaining the variability of spirometry results. Although none of the risk factors were specifically determinant to the symptom questions, bronchodilator test or spirometric measurements, having a mother who smokes seems more important than living in a polluted area if statistically non-significant trends are considered.

Perinatal risk factors for recurrent wheeze in early life.

The possible value of tidal flow volume (TFV) loops measured at birth in relation to the risk of developing recurrent or persistent bronchial obstruction within two years of life was assessed. TFV loops were measured at a mean age of 2.7 days in 802 neonates enrolled in the 'Environment and Childhood Asthma' (ECA) study in Oslo. Of these, 77 children developed recurrent or persistent bronchial obstruction (cases) and were included in a nested case-control study within the ECA study; 88 controls (the child born closest in time to the case), with no history of bronchial obstruction in the first two years of life, were also included. Information on socio-economic factors, parental atopic diseases and parental smoking habits during the pregnancy was collected from a questionnaire completed by the parents in the maternity ward, and cord blood IgE (CB-IgE) was determined as part of routine sampling in the delivery ward. Mean tPTEF/tE (time to reach peak flow to total expiratory time) was slightly lower in cases (0.31; 95% CI 0.28-0.34) than in controls (0.33; 0.31-0.35) (difference not significant), whereas geometric mean CB-IgE was significantly higher among cases (0.39; 0.30-0.52) than controls (0.27; 0.23-0.33). No significant differences between cases and controls were found for respiratory rate, peak tidal expiratory flow or expiratory volume. However, the odds ratio for developing recurrent or persistent bronchial obstruction was 3.5 (1.1-11.6) if tPTEF/tE was < 0.20 and 4.1 (1.1-14.5) with maternal daily smoking during the pregnancy, after adjusting for age, weight, sex, CB-IgE, parental atopy, maternal education and family income. The TFV parameter tpTEF/tE < 0.20 measured within the first week of life as well as maternal daily smoking during pregnancy are significant, independent risk factors for developing recurrent or persistent bronchial obstruction within the first two years of life.

Exposure to environmental tobacco smoke during the first five years of life-results of a prospective birth cohort study

Objective: To exanine links between environmental tobacco smoke (ETS)-exposure and urnary cotinine excretion during the first five years of life. Design: Prospective birth cohiort study Patients: 307 children from the Genran Multicenter Atopy Study (MAS-90) Measurements and results: ETS-exposure was investigated by questionnaires about the parental smoking habits at home and by analysis of urinary cotinine exacetion by the children at 1 year, 4 years and 5 years of age (capillary gas-chromatography). Results: From age 1 year to age 5 five years, the proportion of children growig up in smoker households remiained nearly constant (42%). However, 17% of the initial smoker households changed to non smoker households and vice versa. Within the smoker housholds the percentage of smoldng mothers increased from 19.9% to 25.7% and the percentage of smoking fathers decreased from 29.7% to 20.7%. 77% of the mothers and 60% of the fathers smoldng in the households when the child was 1 year old smoked continuously until children were 5 years old. The daily number of cigarettes smoked in the smoker households remained nearly constant (mean value: 6 cig/day). Urnary cotinine excretion of the ETS-exposed children was found to peak at 1 year of age, decreasing significantly to 5 years of age (p = 0.02). From age 1 year to age 5 years there was a significant correlation between the urinary cotinine excretion of the children and the number of daily cigarettes smoked in the households (p &lt; 0.01). At age 1 year, cotinine excretion was further influenced by the season of the year, the size of domestic apartment and the presence of an atopic mother. At age 5 years, cotinine excretion of the children living in smoker households and attending a kindergarten was significantly lower than that of children living in smoker households but not attending a kindergarten (&lt; O.000 1). Conclusion: Our results show that ETS-exposure passes through a peak during infancy. This suggests, that the reduced association between ETS-exposure and respiratory symptoms in children after age 2 years reported by earlier studies is due to an agedependent reduction of the ETS-exposure.

Effect of pre‐ and postnatal tobacco smoke exposure on specific sensitization to food and inhalant allergens during the first 3 years of life

The study aimed to assess the effect of pre- and postnatal tobacco smoke exposure on specific sensitization to food allergens and inhalant allergens during the first 3 years of life. A total of 342 children of a prospective and observational birth cohort study on atopy (MAS) were included on the basis of a complete follow-up of specific IgE measurements at the ages of 1, 2, and 3 years with available questionnaire information about the parental smoking habit at birth, 18 months, and 3 years of age. Study children were grouped into four exposure categories representing in utero and postnatal environmental tobacco smoke (ETS) exposure, and according to the number of cigarettes smoked by the parents. The effect on the development of allergic sensitization to food, outdoor, and indoor allergens by 3 years of age was determined by multiple logistic regression analyses. At the age of 3, children who were pre- and postnatally exposed to tobacco smoke had a significantly higher risk of sensitization to food allergens (odds ratio: 2.3, 95% C.I.: 1.1-4.6) than unexposed children. Children who were only postnatally exposed by a smoking mother also had a 2.2 times higher risk (95% C.I.: 0.9-5.9) of sensitization than unexposed children. These two categories (pre- and/or postnatal exposure) contribute to the significant overall effect of the tobacco smoke exposure (P< or =0.02). No significant association between tobacco smoke exposure and specific sensitization to inhalant allergens was observed. The determining risk factors for this type of sensitization were atopic family history and mite- and cat-allergen exposure levels. During the first 3 years of life, both prenatal and postnatal tobacco smoke exposure has an adjuvant effect on allergic sensitization which seems to be restricted to allergens to which children are mainly exposed, in combination with the peak of the ETS exposure around the first birthday.