American Journal of Epidemiology Advance Access originally published online on May 28, 2008
American Journal of Epidemiology 2008 168(2):170-178; doi:10.1093/aje/kwn105
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ORIGINAL CONTRIBUTIONS |
Perinatal Factors and the Risk of Asthma in Childhood—A Population-based Register Study in Finland
1 Department of Health Promotion and Chronic Disease Prevention, National Public Health Institute, Helsinki, Finland
2 Tampere School of Public Health, University of Tampere, Tampere, Finland
3 Department of Health and Functional Capacity, National Public Health Institute, Helsinki, Finland
4 Finnish Office for Health Technology Assessment, National Research and Development Center for Welfare and Health, Tampere, Finland
5 Pediatric Research Center, Tampere University Hospital, Tampere, Finland
6 Social Insurance Institution, Helsinki, Finland
7 Information Division, Alcohol and Drug Statistics and Reproduction Statistics, National Research and Development Center for Welfare and Health, Helsinki, Finland
8 Research Unit, Tampere University Hospital, Tampere, Finland
Correspondence to Johanna Metsälä, Department of Health Promotion and Chronic Disease Prevention, National Public Health Institute, Mannerheimintie 166, FIN-00300 Helsinki, Finland (e-mail: johanna.metsala{at}ktl.fi).
Received for publication October 31, 2007. Accepted for publication March 27, 2008.
The aim of the study was to assess whether perinatal factors are associated with the risk of asthma in childhood in a register-based, nested case-control study in Finland. All children born between January 1, 1996, and April 30, 2004, who were entitled to a special reimbursement for antiasthmatic drugs (i.e., had diagnosed asthma by 2006 and had purchased inhaled corticosteroids or montelukast at least once), were identified (n = 21,038). For each case, one matched control child was selected. The associations between perinatal factors, derived from the Finnish Medical Birth Register, and the risk of asthma were analyzed by conditional logistic regression. In the final multivariate model, maternal asthma, young age, smoking, previous miscarriages, and a high number of previous deliveries, as well as cesarean section, low gestational age, and low ponderal index, were associated with an increased risk of asthma in children diagnosed before the age of 3 years. Among children diagnosed at the age of 3 years or later, maternal asthma, low gestational age, and low ponderal index were associated with an increased risk, and a high number of previous deliveries was associated with a decreased risk of asthma. In conclusion, perinatal factors play a role in the development of asthma in childhood, but the etiology may differ in early and late-onset asthma.
asthma; cesarean section; child; cohort studies; gestational age; registries; risk factors
Abbreviations: ATC, Anatomical Therapeutic Chemical; CI, confidence interval; OR, odds ratio; SGA, small for gestational age