Long-term prospective study in children after respiratory syncytial virus infection. Involuntary smoking and incidence of respiratory illness during the first year of life. Asthma and wheezing in the first six years of life. The Group Health Medical Associates. Prospectively assessed incidence, severity, and determinants of respiratory symptoms in the first year of life. Incidence of acute respiratory infections and the relationship with some factors in infancy in Antalya, Turkey. The Indoor Air and Children's Health Study: Methods and Incidence Rates Urinary cotinine and parent history (questionnaire) as indicators of passive smoking and predictors of lower respiratory illness in infants. Recurrent wheezing in very preterm infants. Acute respiratory illness in Adelaide children: breast feeding modifies the effect of passive smoking. Recurrent wheezing in relation to environmental risk factors in infancy The effect of genetic and environmental factors on the prevalence of allergic disorders at the age of two years Risk factors for acute respiratory tract infections in young Greenlandic children. Relationship of parental smoking to wheezing and nonwheezing lower respiratory tract illnesses in infancy. Group Health Medical Associates. Risk Factors for Wheezing during Infancy A Study of 5953 Infants Prevalence of acute respiratory tract infection and its risk factors in under five children. The effects of maternal smoking on early mucosal immunity and sensitization at 12 months of age. Food and drug reactions, wheezing, and eczema in preterm infants. Infant admissions to hospital and maternal smoking. Environmental factors and symptoms in infants at high risk of allergy.
We have prospect ively evaluated for the past 8 years 29 children who were hospitalized during infancy with acute lower respiratory tract illness caused by respiratory syncytial virus ( RSV ) . No differences in the prevalence of a family history of atopy or breast-feeding in these infants compared with controls were noted . However , a history of parental smoking was significantly associated with hospital admission for RSV lower respiratory tract disease . Evidence of atopy , as defined by serum IgE levels and radioallergosorbent testing , have developed in only three ( 10 % ) of 29 children . Six children ( 21 % ) continue to have recurrent lower respiratory tract disease . Fifty-five percent of these children had abnormally low oxyhemoglobin levels ( SaO2 ) measured by ear oximetry for the first 3 to 4 years after the acute illness . Twenty-one percent have persistently low SaO2 levels during the eighth year of follow-up . Spirometric values indicate evidence of peripheral airway obstruction . These studies suggest that an association between RSV lower respiratory tract infections and chronic abnormalities of pulmonary function may be detected sequentially through the first 8 years of life . These abnormalities are not limited to those children developing an atopic state during that same time period A prospect i ve study of 1,144 infants and their families was performed . Smoking and family histories were evaluated with respect to the incidence of lower respiratory disease during the first year of life . It was found that ( 1 ) tracheitis and bronchitis occurred significantly more frequently in infants exposed to cigarette smoke in the home , ( 2 ) maternal smoking imposed greater risks upon the infant than paternal smoking , ( 3 ) occurrence of neither tracheitis nor bronchitis showed a consistent relationship to the number of cigarettes smoked , ( 4 ) a family history that was positive for respiratory illness ( chronic cough or bronchitis ) significantly influenced the incidence of bronchitis , ( 5 ) too few cases of laryngitis and pneumonia were seen to warrant any opinions regarding the adverse influence of either smoking or a family history that was positive for respiratory illness , and ( 6 ) occurrence of bronchiolitis was not affected by the presence of a smoker nor influenced by a family history that was positive for respiratory illness . It is concluded that passive smoking is dangerous to the health of infants and that infants born to families with a history that is positive for respiratory illness ( chronic cough or bronchitis ) are at risk of developing bronchitis BACKGROUND Many young children wheeze during viral respiratory infections , but the pathogenesis of these episodes and their relation to the development of asthma later in life are not well understood . METHODS In a prospect i ve study , we investigated the factors affecting wheezing before the age of three years and their relation to wheezing at six years of age . Of 1246 newborns in the Tucson , Arizona , area enrolled between May 1980 and October 1984 , follow-up data at both three and six years of age was available for 826 . For these children , assessment s in infancy included measurement of cord-serum IgE levels  ( measured in 750 children ) , pulmonary-function testing before any lower respiratory illness had occurred ( 125 ) , measurement of serum IgE levels at nine months of age ( 672 ) , and question naires completed by the children 's parents when the children were one year old ( 800 ) . Assessment s at six years of age included measurement of serum IgE levels  ( in 460 ) ,  pulmonary-function testing  ( 526 ) , and  skin allergy testing  ( 629 ) . RESULTS At the age of six years , 425 children ( 51.5 percent ) had never wheezed , 164 ( 19.9 percent ) had had at least one lower respiratory illness with wheezing during the first three years of life but had no  wheezing at six years of age , 124 ( 15.0 percent ) had no  wheezing  before the age of three years but had wheezing at the age of six years , and 113 ( 13.7 percent ) had wheezing both before three years of age and at six years of age . The children who had wheezing before three years of age but not at the age of six had diminished airway function ( length-adjusted maximal expiratory flow at functional residual capacity [ Vmax FRC ] ) both before the age of one year and at the age of six years , were more likely than the other children to have mothers who smoked but not mothers with asthma , and did not have elevated serum IgE levels or skin-test reactivity . Children who started wheezing in early life and continued to wheeze at the age of six were more likely than the children who never wheezed to have mothers with a history of asthma ( P < 0.001 ) , to have elevated serum IgE levels ( P < 0.01 ) , to have normal lung function in the first year of life , and to have elevated serum IgE levels ( P < 0.001 ) and diminished values for VmaxFRC ( P < 0.01 ) at six years of age . CONCLUSIONS The majority of infants with wheezing have transient conditions associated with diminished airway function at birth and do not have increased risks of asthma or allergies later in life . In a substantial minority of infants , however , wheezing episodes are probably related to a predisposition to asthma Respiratory symptoms are common in infancy . Nevertheless , few prospect i ve birth cohort studies have studied the epidemiology of respiratory symptoms in normal infants . The aim of this study was to prospect ively obtain reliable data on incidence , severity , and determinants of common respiratory symptoms ( including cough and wheeze ) in normal infants and to determine factors associated with these symptoms . In a prospect i ve population -based birth cohort , we assessed respiratory symptoms during the first year of life by weekly phone calls to the mothers . Poisson regression was used to examine the association between symptoms and various risk factors . In the first year of life , respiratory symptoms occurred in 181/195 infants ( 93 % ) , more severe symptoms in 89 ( 46 % ) . The average infant had respiratory symptoms for 4 weeks and 90 % had symptoms for less than 12 weeks ( range 0 to 23 ) . Male sex , higher birth weight , maternal asthma , having older siblings and nursery care were associated with more , maternal hay fever with fewer respiratory symptoms . The association with prenatal maternal smoking decreased with time since birth . This study provides reliable data on the frequency of cough and wheeze during the first year of life in healthy infants ; this may help in the interpretation of published hospital and community-based studies . The apparently reduced risk in children of mothers with hayfever but no asthma , and the decreasing effect of prenatal smoke exposure over time illustrate the complexity of respiratory pathology in the first year of life BACKGROUND Acute respiratory infections ( ARI ) are one of the major problems of childhood in developing countries . The objective of the study was to obtain the incidence of ARI and its risk factors in Antalya , Turkey . METHODS We carried out a prospect i ve cohort study on 204 infants who were born between 1 November and 31 December 1997 , in the area of two primary health-care units in the Antalya city center . The research group was followed periodically every 2 months by home visits and the infants were investigated to determine their symptoms of ARI . The weight and length of children were measured in every home visit . Additional questions about socioeconomic status , some environmental characteristics , and nutrition practice were asked . Data were entered into the computer and the Z-scores were calculated by the Epi Info 5 package program . The incidence rates , relative risks and confidence intervals were calculated by Microsoft Excel version 5.0 program . RESULTS The incidence of ARI was 6.53 episodes per child per year among the children in the research group . The factors that influenced the incidence of ARI were lack of mother 's and father 's education , heating by wood stove , being a low-birthweight infant , not being completely breast-fed in the first 4 months of life and being stunted . There were no associations between the number of persons per room or smoking status of family members with ARI incidence . CONCLUSION Our results demonstrated that ARI were also associated with some socioeconomic , environmental and nutritional status characteristics such as paternal education , house ownership , breast-feeding , stunting , prematurity and burning of biomass fuels in Turkey The Indoor Air and Children 's Health Study is a prospect i ve cohort study of the relation between indoor air pollution  and lower respiratory illness ( LRI ) during the first 2 years of life . Information on family and household characteristics was obtained from a health maintenance organization for 1,424 infants enrolled at birth . Data on LRI were abstract ed from medical records . The incidence of all LRI was 48.4 per 100 child-years . Wheezing-associated respiratory illness (WARI)/ asthma was the most common specific LRI , with an incidence of 11.5 per 100 child-years . Total LRI incidence was lowest during the first 6 months of life . Girls had lower incidence than boys [ rate ratio ( RR ) = 0.8 ; 95 % confidence interval ( CI ) = 0.7–0.8 ) ] . With the exception of croup , all LRI were most common during February and March . These results are comparable with those of other prospect i ve studies . Consistent with other studies , self-reported maternal smoking demonstrated an RR of 1.5 ( 95 % CI = 1.2–1.8 ) for total LRI , but the association varied for specific LRIs from 2.3 ( 95 % CI = 1.5–3.0 ) for WARI/asthma to 1.0 ( 95 % CI = 0.7–1.6 ) for bronchitis Studies of the effects of passive smoking on  lower respiratory illness ( LRI ) have relied on question naires to measure exposure . We studied the association between two measures of passive smoking and the incidence of acute LRI in infants . We analyzed data from a community-based cohort study of respiratory illness during the first year of life in North Carolina . The incidence of LRI was determined by telephone calls at 2-week intervals . Environmental , demographic , and psychosocial risk factors for LRI were measured during home interviews . Tobacco smoke exposure was measured as the mean number of cigarettes smoked per day in the infant 's presence . Smoke absorption by the infants was measured by the urinary cotinine/ creatinine ratio . Of the 485 infants in the study , 325 ( 67 % ) had telephone follow-up and at least two home interviews . In bivariate analyses , reported tobacco smoke exposure and urinary cotinine were associated with LRI . Only the association between reported exposure and LRI remained significant after adjusting for confounders , [ adjusted incidence of LRI ( episodes/child-year ) non-exposed : 0.6 ; < or = 10 cigarettes/day : 0.9 ( RR 1.5 , 95 % CI : 1.1 , 2.0 ) ; > 10 cigarettes/day : 1.3 ( RR 2.2 , 95 % CI : 1.3 , 3.8 ) ] . We conclude that infants reportedly exposed to tobacco smoke have an increased incidence of LRI . There are differences between question naire and biochemical measures of passive smoking . Urinary cotinine will not necessarily improve the validity of studies of the relationship of passive smoking to LRI in infants AIMS : To document the prevalence of , and identify risk factors for ,  recurrent wheezing treated with bronchodilators in the first year of life . METHODS : Parental history and neonatal data were collected prospect ively in a regional cohort of very preterm infants ( < 33 weeks ) .  Data on maternal smoking , siblings at home , breast feeding , respiratory symptoms , and hospital re-admissions were documented at 12 months . RESULTS : Outcome data were available for 525/560 ( 95 % ) of survivors . The incidence of recurrent wheeze was 76/525 ( 14.5 % ) in very preterm infants and 20/657 ( 3 % ) in a cohort of term newborns . Significant risk factors for recurrent wheeze in very preterm infants were parental history of asthma , maternal smoking , siblings at home , neonatal oxygen supplementation at 28 days , 36 , and 40 weeks of gestation . CONCLUSIONS : Wheezing respiratory illnesses are common in very preterm infants . The factors involved are similar to those in more mature infants , with the addition of immaturity and neonatal lung injury STUDY OBJECTIVE --The aim was to investigate the relation between  passive smoking and childhood acute respiratory illness .  DESIGN --The study involved an initial postal survey on a r and om sample of children followed by a case-control study based on the survey . A respiratory illness score was calculated from maternal reports of episodes of illness in the previous 12 months . SETTING --The study was a population survey based on Adelaide metropolitan area in South Australia . PARTICIPANTS --The reference population ( n = 13,996 ) was all live born children registered in South Australia in 1983 whose parents lived in Adelaide metropolitan area . Of these , 4985 families were contacted by post and from 2125 respondents , 1218 ( 58 % ) gave consent for home interview .  " Cases " were children with respiratory illness scores in the top 20 % , controlling for age and time of year ( n = 258 ) ; " controls " were taken in the bottom 20 % ( n = 231 ) . MEASUREMENTS AND MAIN RESULTS --Maternal smoking in the first year of life was associated with a doubling in relative odds of respiratory proneness in the child ( odds ratio = 2.06 , 95 % CI 1.25 - 3.39 ) after adjustment for confounding by parental history of respiratory illness , other smokers in the home , use of group child care , parent 's occupation , and levels of maternal stress and social support . There was no evidence that this association was attributable to differences in the way smoking and non-smoking parents perceived or managed childhood acute respiratory illness . Maternal smoking in the first year , without smoking in pregnancy , was also associated with increased risk of respiratory proneness ( odds ratio 1.75 , 95 % CI 1.03 - 3.0 ) , showing an effect of passive smoking independent of any in utero effect . There was a strong negative effect modification by breast feeding : relative odds of respiratory proneness with maternal smoking were seven times higher among children who were never breast fed than among those who were breast fed . CONCLUSIONS --The results suggest a relatively small but real effect of passive smoking on childhood acute respiratory illness . Effect modification by breast feeding may be due to a combination of behavioural and biological mechanisms Clinical course and environmental factors were recorded in a prospect i ve study of 276 unselected infants followed from birth to the age of 18 months . The study was performed with a question naire at the age of 6 and 12 months and a physical examination at 18 months . Fifty‐nine ( 21 % ) of the children had ≥2 episodes of wheezing before they were 18 months old . A total of 58 ( 21 % ) of the children belonged to the lowest social class V , 182 ( 66 % ) were daily exposed to passive tobacco smoking at home and /or in daycare , 164 ( 59 % ) were breastfed ≥3 months , 192 ( 70 % ) were in daycare , 62 ( 22 % ) lived in Hats and 167 ( 61 % ) were in daily contact with furred pets at home and /or in daycare . In social class V a preponderance of children were exposed to passive tobacco smoking , a majority were living in flats and a minority were breastfed ≥ 3 months . Linear logistic regression analysis was used for the purpose of assessing the causal effect of environmental risk factors on the risk of recurrent episodes of wheezing before the age of 18 months . The study demonstrated that male sex and daily exposure to passive tobacco smoking were significant risk factors with estimated odds ratios 1.9 and 2.4 , respectively . Maternal tobacco smoking seemed to be associated with the higest risk . There was a tendency – though not significant – indicating that breastfeeding ≥ 3 months had a protective effect . Low social status , daycare , daily contact with furred pets , having carpeted floor in bedroom , and living in a flat proved not to affect significantly the risk of recurrent wheezing The effect of genetic and environmental factors on the prevalence of allergic disorders in early childhood was determined in a prospect i ve follow‐up study . Information was available on 1174 children at the age of 2 years . Two‐hundred and seventy‐five were considered to have an allergic disorder . The prevalence varied from 3.2 % for rhinitis to 10.9 % , for asthma . At 2 years 60 children reacted positively on skin‐prick test ( SPT ) . Multivariate logistic regression analysis was used to obtain adjusted odds ratios ( 95 % confidence interval ) for each factor . For asthma , positive family history , male sex , low birth‐weight , maternal smoking and season of birth were significant risk factors . For eczema , positive family history was the only significant risk factor . For rhinitis , lower socio‐economic group and autumn birth were significant . Maie sex and low birth‐weight were significant for skin test positivity . Positive family history and low birth‐weight were significant risk factors for any allergy . Low birth‐weight was also a significant risk for skin test reactivity to house dust mite . Genetic and environmental factors have a profound effect on the development of allergic disorders in the first two years of life Acute respiratory infections cause considerable morbidity among Inuit children , but there is very little information on the risk factors for these infections in this population . To identify such factors , the authors performed a prospect i ve community-based study of acute respiratory infections in an open cohort of 288 children aged 0 - 2 years in the town of Sisimiut , Greenl and . Between July 1996 and August 1998 , children were monitored weekly , and episodes of upper and lower respiratory tract infections were registered . Risk factor analyses were carried out using a multivariate Poisson regression model adjusted for age . Risk factors for upper respiratory tract infections included attending a child-care center ( relative risk = 1.7 compared with home care ) and sharing a bedroom with adults ( relative risk = 2.5 for one adult and 3.1 for two adults ) . Risk factors for lower respiratory tract infections included being a boy ( relative risk = 1.5 ) , attending a child-care center ( relative risk = 3.3 ) , exposure to passive smoking ( relative risk = 2.1 ) , and sharing a bedroom with children aged 0 - 5 years ( relative risk = 2.0 for two other children ) . Breastfeeding tended to be protective for lower respiratory tract infections . The population -attributable risk of lower respiratory tract infections associated with passive smoking and child-care centers was 47 % and 48 % , respectively . The incidence of acute respiratory infections among Inuit children may be reduced substantially through public health measures The relationship between parental smoking and lower respiratory tract illness ( LRI )  was studied in a large cohort of infants followed prospect ively from birth . Illnesses were diagnosed by physicians using agreed-on criteria , and parental smoking histories were obtained by question naire . The LRIs were differentiated into wheezing and nonwheezing episodes , and the age at first illness of either type was evaluated in relation to smoking by parents . The odds of having an LRI were significantly higher in children whose mothers smoked ( odds ratio 1.52 ; confidence interval 1.07 to 2.15 ) . The odds were higher if the mother smoked a pack of cigarettes or more per day and if the child stayed home rather than attending day care ( odds ratio 2.8 ; confidence interval 1.43 to 5.5 ) . Logistic regression indicated that the LRI rate was significantly elevated both in children exposed to heavy maternal smoke in the absence of day care , and in those who use day care but were not exposed to maternal smoking of a pack or more per day . These findings could not be attributed to other confounding variables . Neither paternal smoking nor smoking by other household members was consistently related to the LRI rate . The relationship of maternal smoking to LRI rate was evident for both wheezing and nonwheezing illnesses . Maternal smoking of a pack or more per day was also related to an early age at first LRI , for both wheezing ( p less than 0.05 ) and nonwheezing ( p less than 0.002 ) illnesses . In sum , maternal smoking is associated with a higher rate of LRIs in the first year , particularly when mothers smoked a pack or more per day and when the child did not use day care Risk factors for the development of  wheezing  during infancy were studied in 5953 children . The data for the study were collected from a large prospect i ve investigation of children born in 1959–61 , who had attended a one‐year follow‐up examination . Wheezing was diagnosed when the symptom had been observed at least once during the first year of life , not in conjunction with pneumonia , epiglottitis or acute laryngitis .  Logit analysis was used for the purpose of assessing the causal effect of environmental and other factors on the risk of wheezing among infants . The assessment of a risk factor by means of regression technique , requires certain other variables to be included in the regression model . A general rule concerning inclusion of other variables has been formulated and applied to the above data . The study demonstrated that the risk of wheezing was affected by a number of factors — particularly environmental . Poor social environment increases the risk of wheezing , as does the mother 's smoking , and placement of the baby in day‐care . Boys experienced wheezing more often than girls . Premature infants are more liable to develop wheezing than mature children . Remarkably , children born in the period April through September develop wheezing , but not bronchitis , more often than children born in October through March This study was undertaken to determine the prevalence and risk factors of the disease among under five children in a rural community . Three villages were r and omly selected from the Ghoraghat thana of Dinajpur district . All under five children were followed once a month for consecutive four months and all the target variables were checked and recorded in the question naire . 566 out of the total of 965 under five children had ARI episodes during the study period . The prevalence of ARI in the community was 58.7 % . However , the incidence in both sexes were 14.7 % . It was 14.9 % and 14.4 % in male and female respectively . The mean number of episodes of ARI was 1.75 per child per year . Among studied risk factors , malnutrition ( 63 % vs. 37 % ) , illiteracy ( 64 % vs. 36 % ) , poverty ( 62 % vs. 38 % ) , overcrowding ( 62 % vs. 38 % ) and parental smoking ( 61 % vs. 39 % ) were found in significantly higher proportions in ARI victims compared to those without ARI . These observations emphasize the need for research aim ed at health system to determine the most appropriate approaches to control acute respiratory infection and thus could be utilized to strengthen the ARI control programme With the dramatic rise in asthma and respiratory disease , there is an urgent need to determine the effects of common environmental exposures on early immune development . In this study , we examined the effects of maternal smoking as a major adverse exposure in early life , on mucosal immune function and allergen sensitization in the first year of life . A cohort of 60 smokers and 62 non-smokers was recruited in pregnancy , and followed prospect ively at 3 and 12 months of age for saliva collection [ for immunoglobulin ( Ig ) A measurements ] , urine collection ( for cotinine levels ) and clinical assessment s ( for allergy and infection history ) . Allergen skin-prick tests were also performed at 12 months of age . Specific IgA to common colonizing bacteria was measured on saliva sample s , including pneumococcal polysaccharide ( PS ) serotype 14 and non-typeable Haemophilus influenza ( NTHI ) outer membrane protein 6 ( OMP6 ) . Eighty-two mothers and their infants completed the 12-month follow-up period--56 in the maternal non-smoking group and 26 in the maternal smoking group . Maternal smoking was associated with significantly higher total infant salivary IgA at 12 months of age ( p = 0.026 ) , and more chronic upper respiratory tract symptoms ( p = 0.012 ) . However , there were no differences in the level of specific IgA antibodies to common colonizing bacteria ( pneumococcal PS serotype 14 and NTHI OMP6 ) . In general , the IgA levels at 12 months were higher in children who had more chest infections in the first year ( Kendall 's tau b , 0.282 ; p = 0.003 ) . There was also a trend of lower respiratory tract symptoms ( wheeze ) ( p = 0.142 ) in infants of smokers . There were no effects of maternal smoking on the rates of allergen sensitization , atopic dermatitis and food allergy at 12 months of age . In conclusion , maternal smoking did not inhibit the production of anti-microbial IgA , suggesting that other factors are responsible for the increased susceptibility to infection in these infants . The increased mucosal inflammation in these children was not associated with effects on early allergy propensity Allergic reactions were investigated in 777 preterm infants who were r and omly assigned to early diet and followed up to 18 months post term .  Wheezing or asthma was common ( incidence 23 % ) ; it was associated with neonatal ventilation , maternal smoking , and a family history of atopy and was unexpectedly reduced in babies born by caesarean section . Even in non-ventilated infants , the incidence of subsequent wheezing was 18 % , rising to an estimated 44 % ( using logistic regression ) when the foregoing risk factors ( excluding ventilation ) were present .  Eczema occurred in 151 infants ( 19 % ) and was strongly associated with  multiple pregnancy  ( 30 % incidence in twins or triplets ) . Reactions to cows ' milk ( incidence : 4.4 % from detailed history ; 0.8 % confirmed by challenge ) , other foods ( 10 % ) , and drugs ( 5 % ) were within the range reported in full term infants . Milk and food reactions were associated with multiple pregnancy ( 19 % ) and a family history of atopy . Reactions to drugs were least likely to occur in infants who had been ventilated and were on multiple medications in the neonatal period , suggesting that drug tolerance may have developed . We speculate that preterm infants may be a high risk group for asthma and eczema , which could imply an association between atopy and prematurity Abstract Admissions to hospital during the first year of life were recorded in a prospect i ve study of 10,672 infants whose mothers ' smoking habits were known . Infants with major congenital malformations , and those dying before their first birthday , were excluded . The infants of mothers who smoked had significantly more admissions for bronchitis or pneumonia , especially in the winter , and more injuries . They were also admitted more frequently , though not significantly so , for upper-respiratory-tract infections , gastroenteritis , childhood infectious diseases , and other diagnoses . The excess of bronchitis and pneumonia in the group exposed to smoke increased with increasing number of cigarettes smoked by the mother . It occurred within subgroups of birth-weight , social class , and birth order . It was seen mainly in infants aged 6 - 9 months , while at older and younger ages there was no significant effect of maternal smoking . The findings support the hypothesis that atmospheric pollution with tobacco smoke endangers the health of non-smokers STUDY OBJECTIVE : To identify environmental determinants of six symptoms associated with allergic disease in infancy . DESIGN : Infants were participants in a prospect i ve r and omised controlled trial of feeding practice s in families with a history of atopy . SETTING : Infants were recruited in two maternity hospitals in S Wales and followed up in the community for 1 year . PARTICIPANTS : Mothers of 519 infants agreed to participate , but 36 were excluded ( mainly for moving home or failing to attend for follow-up ) , leaving 483 in the study ( 253 male , 230 female ) . Infants were followed up and examined for evidence of allergic disease at 3 , 6 , and 12 months . MEASUREMENTS AND MAIN RESULTS : At each examination , mothers were question ed about episodes of illness in the infant , and the data presented relate to ( reported and observed ) eczema and nasal discharge , and ( reported ) wheeze , prolonged colds , diarrhoea and vomiting . Mothers kept a diary with details of feeding for the first 6 months . All homes were visited by a nurse who took sample s of dust for dust mite antigen analysis . Extensive socio-demographic data were collected . None of the factors studied showed a convincing relationship with eczema . In a multiple logistic regression analysis breast feeding appeared to protect against wheeze , nasal discharge , colds , vomiting and diarrhoea . Having more siblings increased the likelihood of prolonged colds , and ( together with overcrowding ) of wheeze and nasal discharge . Maternal smoking and low social class were associated with wheeze , and house dust antigen with prolonged colds . Respiratory symptoms were associated with some aspects of housing but these could not be distinguished clearly from other social factors . Babies born in Autumn were at increased risk of wheeze , vomiting and diarrhoea . CONCLUSIONS : Environmental factors play an important part in determining risk of symptoms in potentially atopic babies . These factors are in principle open to manipulation
Background Passive smoke exposure increases the risk of  lower respiratory infection ( LRI ) in infants , but the extensive literature on this association has not been systematic ally review ed for nearly ten years .
The aim of this paper is to provide an up date d systematic review and meta- analysis of studies of the association between passive smoking and LRI , and with diagnostic subcategories including bronchiolitis , in infants aged two years and under .
Strategies to prevent passive smoke exposure in young children are an urgent public and child health priority