Birth characteristics and acute otitis media in early life

Objective: To assess whether preterm birth and low birth weight were associated with single and recurrent episodes of acute otitis media (AOM) the first 18 months of life.

Methods: The study population consisted of 33,192 children in the Norwegian Mother and Child Cohort, conducted at the Norwegian Institute of Public Health. The majority of all pregnant women in Norway were invited to participate and the response rate was 44%. Participating women received questionnaires during pregnancy and when the child was 6 and 18 months. Main outcome measures were maternal reports of AOM at ages 6, 11 and 18 months. Information on birth weight and gestational age was obtained from the Medical Birth Registry of Norway. Regression analyses were performed controlling for a variety of potential confounders.

Results: Preterm birth was slightly associated with both single and recurrent episodes of AOM the first 18 months of age. The adjusted relative risk (aRR) for having any episode of AOM was 1.37, 95%CI (1.12-1.68) if born before week 33, and the aRR for having recurrent AOM was 1.34, 95%CI (1.01-1.77) if born in weeks 33-36 (reference group: >or=37 weeks). A corresponding tendency was not found for low birth weight.

Conclusions: The finding indicates a modest increased risk of having AOM in children born preterm, and preterm birth seems to be more important than low birth weight in determining risk of having AOM in early life.