Risk of childhood asthma in relation to the timing of early child care exposures.
OBJECTIVE
To examine whether early child care exposure influences the risk for development of asthma.


METHODS
Longitudinal data from 939 children and their families from the National Institute of Child Health and Development Study of Early Child Care and Youth Development were analyzed. Exposure to other children in the primary child care setting as an infant (before 15 months) and as a toddler (16-36 months) were assessed as risk factors for persistent or late-onset asthma by age 15 via logistic regression.


RESULTS
The number of children in the child-care environment when the child was a toddler was significantly associated with odds of asthma, even after adjusting for respiratory illnesses and other risk factors (P < .05). The fewer the children exposed to as toddlers, the higher the probability of persistent or late-onset asthma by age 15.


CONCLUSIONS
This study supports the theory of a protective effect of exposure to other children at an early age, especially as a toddler, on the risk of asthma. This effect appears to be independent of the number of reported respiratory tract illnesses, suggesting that other protective mechanisms related to the number of children in the child care environment may be involved.
Gurka
Matthew J
MJ
Department of Public Health Sciences, University of Virginia School of Medicine, Charlottesville, VA 22908-0717, USA. mgurka@virginia.edu
Blackman
James A
JA
Heymann
Peter W
PW
D000293:Adolescent; D000367:Age Factors; D017668:Age of Onset; D001249:Asthma / Q000175:diagnosis / Q000453:epidemiology*; D002648:Child; D002654:Child Care / Q000706:statistics & numerical data*; D002656:Child Day Care Centers / Q000706:statistics & numerical data*; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D012307:Risk Factors; D014481:United States
J Allergy Clin Immunol. 1997 Jan;99(1 Pt 1):6-12
9003205
Child Dev. 2003 Jul-Aug;74(4):976-1005
12938694
Am J Respir Crit Care Med. 2003 May 1;167(9):1239-43
12446273
Pediatrics. 1999 Apr;103(4 Pt 1):753-8
10103298
Respir Med. 2007 Jul;101(7):1431-8
17350816
Arch Pediatr Adolesc Med. 2001 Apr;155(4):481-8
11296076
BMJ. 1989 Nov 18;299(6710):1259-60
2513902
Arch Pediatr Adolesc Med. 2002 Feb;156(2):121-6
11814371
Lancet. 1999 Feb 6;353(9151):450-4
9989715
J Allergy Clin Immunol. 1999 Mar;103(3 Pt 1):355-61
10069865
Am J Respir Crit Care Med. 1999 Nov;160(5 Pt 1):1617-22
10556130
Am J Epidemiol. 2009 Jan 15;169(2):195-205
19033160
Am J Respir Crit Care Med. 1998 Aug;158(2):352-7
9700106
Pediatrics. 2004 Sep;114(3):e327-32
15342893
BMJ. 2001 Feb 17;322(7283):390-5
11179155
Thorax. 1999 Aug;54(8):664-9
10413716
Am J Respir Crit Care Med. 1997 Jan;155(1):156-61
9001305
Am J Public Health. 1995 Aug;85(8 Pt 1):1109-12
7625505
Am J Respir Crit Care Med. 2006 Jan 15;173(2):143-63
16210666
N Engl J Med. 1995 Jan 19;332(3):133-8
7800004
Arch Dis Child. 1998 Oct;79(4):328-33
9875043
N Engl J Med. 2000 Aug 24;343(8):538-43
10954761