***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Using a cohort-based design and r and om enrollment , the relation of various risk factors to acute otitis media , respiratory infection and wheezy bronchitis was studied in 2512 children from the fetal period to the age of two years . The complex interrelations of the risk factors with each other were separated out by multivariate analysis , and the confounding effects of antenatal parameters were also st and ardized . Acute otitis media with effusion ( AOME ) , as demonstrated by myringotomy , was analyzed as a specific subgroup of acute otitis media ( AOM ) . Day care in local authority nursery was the major risk factor for both types of acute otitis media . The odds ratio ( OR ) for such children becoming ' otitis-prone ' ( greater than or equal to 3 episodes of AOME ) was 1.8 ( 95 % confidence interval , 1.4 - 2.2 ) . Short duration of breastfeeding involved another significant risk of recurrent respiratory infections and otitis media , the OR for AOME being 1.5 ( 1.1 - 2.0 ) and that for recurrent respiratory infection 1.3 ( 1.1 - 1.6 ) . Allergy and family day care were also significantly associated with infective parameters , but to a lesser extent . The risk factors for wheezy bronchitis were the same as for infections , indicating that wheezy bronchitis is closely related to infections A number of studies in developed countries suggest that breastfeeding protects against infections in infancy . However , the choice to breastfeed is often related to maternal characteristics , and many of these studies are limited in the extent to which they can take account of confounding influences . In a prospect i ve birth cohort study , we assessed the relationship between the duration of breastfeeding and the prevalence of  lower respiratory tract infections , ear infections and gastrointestinal morbidity during the first year of life in 1764 infants . We considered the duration of all breastfeeding , including mixed feeding . Eighty-one per cent of the infants were breastfed initially , and 25 % were breastfed up to 6 months . There were grade d decreases in the prevalence of respiratory and gastrointestinal symptoms between birth and 6 months as breastfeeding duration increased ; these were robust to adjustment for a number of confounding factors . The adjusted relative risks ( 95 % confidence interval ) for infants breastfed for six or more months compared with infants who were never breastfed were 0.72 ( 0.58 - 0.89 ) , 0.43 ( 0.30 - 0.61 ) and 0.60 ( 0.39 - 0.92 ) for general respiratory morbidity , diarrhoea and vomiting , respectively . Duration of breastfeeding  in the second half of infancy was less strongly related to diagnosed respiratory tract infections and gastrointestinal morbidity , although important benefits of breastfeeding were still seen . Our data provide strong support for a protective role of breastfeeding against respiratory and gastrointestinal infections in infancy . The grade d inverse associations with breastfeeding duration suggest that current efforts to promote breastfeeding and increase duration will have important effects in reducing morbidity in infancy A r and om sample of 2512 children was monitored to age 2 years to study the biologic effects of various risk variables on  acute otitis media  using a new dynamic modeling that controls both the confounding effects and time dependency . Dynamic modeling proved to be superior to conventional approaches , both the r and om and systematic error being much smaller and the effect estimates being biologically interpretable . The major risk factors were the existence of a previous episode of acute otitis media in general ( odds ratio , 2.03 ; 95 % confidence interval [ Cl ] , 1.81 to 2.25 ) or particularly during the preceding 3 months ( odds ratio , 3.74 ; 95 % Cl , 3.40 to 4.10 ) and attending a day nursery ( odds radio , 2.06 ; 95 % Cl , 1.81 to 2.34 ) . As the form of day care is the only modifiable risk variable of significant importance and previous episodes entail a risk of future ones , infants should be cared for at home , particularly after they have already experienced an episode of acute otitis media OBJECTIVE We followed a cohort ( N = 306 ) of infants at well-baby visits in two suburban pediatric practice s to assess the relation of exclusive breastfeeding , and other environmental exposures , to episodes of acute otitis media ( AOM ) and otitis media with effusion ( OME ) .  METHODS Detailed prospect i ve information about the exclusiveness of breastfeeding , parental smoking , day care attendance , and family history was obtained at scheduled clinic visits .  Tympanometric and otoscopic examinations  were used in the diagnosis of otitis media ( OM ) . Nasopharyngeal cultures  were performed at 1 - 6 months , and at 8 , 10 , 12 , 15 , 18 , and 24 months of age to detect colonization with middle-ear pathogens . RESULTS Between 6 and 12 months of age , cumulative incidence of first OM episodes increased from 25 % to 51 % in infants exclusively breastfed and from 54 % to 76 % in infants formula-fed from birth . Peak incidence of AOM and OME episodes was inversely related to rates of breastfeeding beyond 3 months of age . A twofold elevated risk of first episodes of AOM or OME was observed in exclusively formula-fed infants compared with infants exclusively breast-fed for 6 months . In the logistic regression analysis , formula-feeding was the most significant predictor of AOM and OME episodes , although age at colonization with middle-ear pathogens and day care ( outside the home ) were significant competing risk factors . A hazard health model suggested additionally that breastfeeding , even for short duration s ( 3 months ) , reduced onset of OM episodes in infancy . CONCLUSIONS Modifiable factors in the onset of AOM and OME episodes during the first 2 years of life include early age at colonization ( < /=3 months of age ) , day care outside the home , and not being breastfed OBJECTIVE This study was design ed to assess the relation of exclusive breast-feeding , independent of recognized risk factors , to  acute and recurrent otitis media in the first 12 months of life . METHODS Records of 1220 infants who used a health maintenance organization and who were followed during their first year of life as part of the Tucson Children 's Respiratory Study were review ed . Detailed prospect i ve information about the duration and exclusiveness of breast-feeding was obtained , as was information relative to potential risk factors ( socioeconomic status , gender , number of siblings , use of day care , maternal smoking , and family history of allergy ) . Acute otitis media and recurrent otitis media , defined as three or more episodes of acute otitis media in a 6-month period or four episodes in 12 months , were the outcome variables . RESULTS Of the 1013 infants followed for their entire first year , 476 ( 47 % ) had at least one episode of otitis and 169 ( 17 % ) had recurrent otitis media . Infants exclusively breast-fed for 4 or more months had half the mean number of acute otitis media episodes as did those not breastfed at all and 40 % less than those infants whose diets were supplemented with other foods prior to 4 months . The recurrent otitis media rate in infants exclusively breast-fed for 6 months or more was 10 % and was 20.5 % in those infants who breast-fed for less than 4 months . This protection was independent of the risk factors considered . CONCLUSION These findings suggest that exclusive breast-feeding of 4 or more months protected infants from single and recurrent episodes of otitis media The authors compared parental reports  with medical records for 157 children enrolled in a prospect i ve study of chronic otitis media with effusion between 1987 and 1991 .  Parents completed a question naire about the child 's past health history , and the research nurse abstract ed history information from the clinic 's medical record . Previous insertion of a tympanostomy tube ( kappa = 0.96 ) and premature birth ( kappa = 0.68 ) were accurately reported , but there was a substantial proportion of missing data for age at first episode of otitis media , occurrence of otitis media the previous summer , and number of episodes in the previous 18 months . Data were significantly more likely to be missing for male children , children with siblings , and those with more episodes . Parents who reported six or more previous episodes for their child overestimated the number compared with the medical record ( 8.7 vs. 7.4 , respectively ; p = 0.01 ) , while those who reported fewer episodes underestimated the number ( 3.1 vs. 4.6 , respectively ; p = 0.01 ) . Episodes of otitis media during the 3 months between study visits were also accurately reported ( kappa = 0.94 ) . The accuracy and completeness of parental  report of the child 's health history was influenced by the chronicity of otitis media , the duration of recall , and the seriousness of the event being recalled Risk factors for acute upper respiratory tract disease in childhood were evaluated in a population -based sample of the Atlanta metropolitan area . Mothers from 449 households containing 575 children less than 5 years of age were selected by r and om-digit dialing and question ed about upper respiratory tract infection and ear infection occurring in their children during the preceding 2 weeks . Household demographic and socioeconomic characteristics , maternal smoking history and child day-care attendance and breast-feeding information were also obtained . For children less than 5 years of age , the reported incidence of upper respiratory tract infection was 24 % , and of ear infection , 6 % . Controlling for the other variables measured , day-care attendance was associated with a significantly increased risk of both illnesses . For upper respiratory tract infection , increased risk was present for all children attending day care ( P = .02 , odds ratio = 1.6 ) , whereas for ear infection , risk could be demonstrated only for full-time attendees ( P = .005 , odds ratio = 3.8 ) . Maternal smoking was a second independent risk factor for a child 's having upper respiratory tract infection ( odds ratio = 1.7 , P = .01 ) . Thirty-one percent of all upper respiratory tract infection among day-care attendees and 66 % of all ear infections among full-time day-care attendees were attributable to day-care attendance . Given the proportion of children in day care , 9 % to 14 % of the total burden of upper respiratory tract disease in this population was day care related . ( ABSTRACT TRUNCATED AT 250 WORDS Acute  otitis media  is the most frequent diagnosis in children visiting physicians ’ offices . Risk factors for otitis media have been widely studied . Yet , the correlation between bacterial carriage and the development of otitis media is not entirely clear . Our aim was to study in a population -based prospect i ve cohort the risk factors for otitis media in the second year of life with special emphasis on the role of colonization with Streptococcus pneumoniae , Haemophilus influenzae and Moraxella catarrhalis . The study was embedded in the Generation R Study . Data on  risk factors and doctor-diagnosed otitis media  were obtained by midwives , hospital registries and postal question naires in the whole cohort ( n = 7,295 ) .  Nasopharyngeal swabs  were obtained at the age of 1.5 , 6 and 14 months in the focus cohort ( n = 1,079 ) . Of these children , 2,515 ( 47.2 % ) suffered at least one period of otitis media in their second year of life . The occurrence of otitis media during the follow-up period in the first 6 months of life and between 6 and 12 months of age was associated with the risk of otitis media in the second year of life ( aOR , 1.83 95 % CI 1.24–2.71 and aOR 2.72 , 95 % CI 2.18–3.38 , respectively ) . Having siblings was associated with an increased risk for otitis media in the second year of life ( aOR 1.42 , 95 % CI 1.13–1.79 ) . No associations were found between bacterial carriage in the first year of life and otitis media in the second year of life . In our study , otitis media in the first year of life is an independent risk factor for otitis media in the second year of life . Surprisingly , bacterial carriage in the first year of life did not add to this risk . Moreover , no association was observed between bacterial carriage in the first year of life and otitis in the second year of life OBJECTIVE Otitis media ( OM ) is an extremely common pediatric diagnosis . Several risk factors have been associated with OM , but the relationship between OM and race/ethnicity remains controversial . We sought to define the relationship between OM diagnosis and race/ethnicity in infants . METHODS By multivariable logistic regression , we evaluated the association between OM diagnosis and race/ethnicity in 11,349 non-low-birthweight infants who were participants in a prospect i ve cohort study of infant care practice s. RESULTS As in previous studies , breastfeeding was associated with a decreased risk of OM diagnosis while other factors were independently associated with a substantially increased risk of OM diagnosis : out-of-home daycare , multiple children living in the home , and mother 's multiparity . Daycare was associated with a " dose effect " in that the risk of OM diagnosis increased with an increasing number of children in the daycare . While the crude analysis suggested little relation of OM diagnosis and race/ethnicity , the association was confounded by several covariates including maternal marital status , number of children living in the home , breastfeeding status , and maternal age . After adjustment for relevant confound 
    Output:
    
This systematic review and meta- analysis provides evidence that breastfeeding protects against AOM until 2 years of age , but protection is greater for exclusive breastfeeding and breastfeeding of longer duration .