Very low birthweight and asthma by age seven years in a national cohort

Several studies have suggested that very low birthweight (VLBW < 1500 g) is associated with increased rates of respiratory problems in childhood and t hat the presence of chronic lung disease further increases the risk. We aim ed to assess rates of asthma at 7-8 years of age in a national cohort of VL BW infants born in 1986 and for whom perinatal data were available. Two hun dred ninety-nine former VLBW children (96% of surviving children living in New Zealand) were assessed at a home visit. Parents were asked a comprehens ive questionnaire, including three questions aimed at assessing morbidity f rom asthma: I)was the child diagnosed as having asthma before age 7 years; 2) was the child still experiencing asthma at the age of 7 years; and 3) wa s the child prescribed daily medication for asthma at the age of 7 years. Overall. 50% of the cohort had been diagnosed with asthma before age 7, com pared with 27% of a sample of New Zealand children assessed contemporaneous ly in an international study; 32% had asthma at age 7, and 11% were taking daily medication. All three categories of asthma were associated with a fam ily history of asthma, but there was no association with any perinatal fact ors. A diagnosis of asthma before age 7 was more likely when the mother smo ked in pregnancy (P < 0.005) and currently smoked (P < 0.01), and trended s o when parents lacked high school qualifications and in Maori or Pacific Is land families (P< 0.10). In contrast, daily medication was more frequent wh en parents had educational qualifications and in non-Maori or Pacific Islan d families (P < 0.05). On multiple logistic regression, a family history of asthma was a significant predictor for any and current asthma (P < 0.001) and daily medication (P < 0.05); maternal smoking in pregnancy was a signif icant predictor for any asthma (P < 0.05); and non-Maori or Pacific Island ethnicity was a significant predictor for asthma treatment (P < 0.05). We conclude that rates of childhood asthma are high in this VLBW cohort, bu t the high prevalence appears to be unrelated to perinatal factors, includi ng respiratory morbidity. There are suggestions that social factors contrib ute to both asthma risk and treatment. Pediatr Pulmonol, 2000; 30:291-296, (C) 2000 Wiley-Liss, Inc.