Rationale: The proportion of low and very low birth weight births is increasing. Infants and children with a history of low and very low birth weight have an increased risk of respiratory illnesses, but it is unknown if clinically significant disease persists into adulthood.
Objectives: To determine if a history of low birth weight is associated with hospitalization for respiratory illness in adulthood.
Methods: This study was a population-based, case-control study. Cases were adults 18 to 27 years of age who were hospitalized for a respiratory illness from 1998 to 2007 within Washington State who could be linked to a Washington State birth certificate for the years 1980 to 1988. Four control subjects, frequency matched by birth year, were randomly selected from Washington State birth certificates for each case patient. Control subjects who died before age 18 were excluded.
Measurements and main results: Two levels of exposure were identified: (1) very low birth weight (birth weight <1,500 g) and (2) moderately low birth weight (birth weight, 1,500-2,499 g). Normal birth weight individuals (2,500-4,000 g) were considered unexposed. Respiratory hospitalizations were defined using discharge diagnosis codes. Logistic regression was used to calculate the odds ratio for hospitalization comparing exposed and unexposed individuals. A total of 4,674 case patients and 18,445 control subjects were identified. The odds ratio for hospitalization for respiratory illness was 1.83 for very low birth weight (95% confidence interval, 1.28-2.62; P = 0.001) and 1.34 for moderately low birth weight (95% confidence interval, 1.17-1.53; P < 0.0005). This association remained after adjustment for birth year, sex, maternal age, race, residence, and marital status.
Conclusions: Adults with a history of very low birth weight or moderately low birth weight were at increased risk of hospitalization for respiratory illness.