Asthma is associated with preterm birth but not with small for gestational age status among a population-based cohort of Medicaid-enrolled children <10 years of age
- 1Alaska Division of Public Health, Section of Epidemiology, Anchorage, Alaska, USA
- 2Centers for Disease Control and Prevention, Office of Workforce and Career Development, Alaska Division of Public Health, Anchorage, Alaska, USA
- Correspondence to:
Bradford D Gessner
Alaska Division of Public Health, Section of Epidemiology, 3601 C Street, Suite 540, PO Box 240249, Anchorage, Alaska 99524, USA; Brad_
- Accepted 19 September 2006
- Revised 5 June 2006
- Published Online First 13 October 2006
Background: Few population-based studies have evaluated the association between birth weight or gestation and subsequent clinically significant asthma.
Methods: Birth records of 37 349 Alaska residents <10 years of age who were enrolled in Medicaid for at least 365 days during 1999–2002 were linked to a Medicaid billing file. The occurrence of asthma and lower respiratory infections during the study period was categorised on the basis of standard International Classification of Diseases 9th Revision codes. The association between gestational age or small for gestational age status and asthma outcomes was adjusted for recent history of lower respiratory infection, years of Medicaid enrolment, age at enrolment and a variety of birth-related factors.
Results: Among children <5 years of age, the adjusted odds ratio (OR) for developing asthma decreased by 5.5% (95% confidence interval (CI) −0.2 to 10.9) and 7.9% (95% CI 5.2 to 10.4) per additional week of gestational age for children without and with any lower respiratory tract infection, respectively. For children ⩾5 years of age, the adjusted OR for developing asthma decreased by 3.4% (95% CI −2.8 to 9.8) and 3.7% (95% CI −2.0 to 9.2) per additional week of gestation for those without and with lower respiratory tract infection, respectively. Among all children with asthma, the adjusted OR for hospitalisation due to asthma decreased by 6.9% (95% CI 2.1 to 11.5) for each additional week of gestational age. Small for gestational age status was not significantly associated with asthma outcomes.
Conclusions: Preterm birth but not small for gestational age status predicted subsequent asthma outcomes. Adverse effects of preterm birth on asthma outcomes persist beyond age 5 years.
Published Online First 13 October 2006
Funding: This work was supported in part by project H18 MC-00004-11 from the Maternal and Child Health Bureau (Title V, Social Security Act), Health Resources and Services Administration, Department of Health and Human Services. BDG has received funding support from Sanofi-Pasteur and TAP Pharmaceuticals.
Competing interests: None declared.
Ethical approval: This study involved linkage of existing legally authorised administrative databases housed at the Alaska Department of Health and Social Services. No novel data were obtained. Under these circumstances of routine public health evaluation, institutional review board approval and informed consent were neither sought nor obtained.
The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the US Centers for Disease Control and Prevention.