Breast-feeding and infant illness: a dose-response relationship?
OBJECTIVE
The purpose of this study was to determine whether breast-feeding has a dose-related protective effect against illness and whether it confers special health benefits to poor infants.


METHODS
The association between breast-feeding dose and illnesses in the first 6 months of life was analyzed with generalized estimating equations regression for 7092 infants from the National Maternal and Infant Health Survey. Breast-feeding dose (ratio of breast-feedings to other feedings) was categorized as full, most, equal, less, or no breast-feeding.


RESULTS
Compared with no breast-feeding, full breast-feeding infants had lower odds ratios of diarrhea, cough or wheeze, and vomiting and lower mean ratios of illness months and sick baby medical visits. Most breast-feeding infants had lower odds ratios of diarrhea and cough or wheeze, and equal breast-feeding infants had lower odds ratios of cough or wheeze. Full, most, and equal breast-feeding infants without siblings had lower odds ratios of ear infections and certain other illnesses, but those with siblings did not. Less breast-feeding infants had no reduced odds ratios of illness. Findings did not vary by income.


CONCLUSIONS
Full breast-feeding was associated with the lowest illness rates. Minimal (less) breast-feeding was not protective. Breast-feeding conferred similar health benefits in all economic groups.
Raisler
J
J
Nurse-Midwifery Program, University of Michigan School of Nursing, Ann Arbor 48109-0482, USA. jraisler@umich.edu
Alexander
C
C
O'Campo
P
P
D000328:Adult; D001942:Breast Feeding / Q000706:statistics & numerical data*; D002662:Child Health Services / Q000706:statistics & numerical data; D003371:Cough / Q000453:epidemiology; D003968:Diarrhea, Infantile / Q000453:epidemiology; D005260:Female; D006306:Health Surveys; D006801:Humans; D007223:Infant; D007229:Infant Welfare / Q000706:statistics & numerical data*; D007231:Infant, Newborn; D008297:Male; D009017:Morbidity; D016017:Odds Ratio; D011203:Poverty / Q000706:statistics & numerical data; D012044:Regression Analysis; D011795:Surveys and Questionnaires; D014481:United States / Q000453:epidemiology; D014839:Vomiting / Q000453:epidemiology