Abstract

JM Harris, P Cullinan, P Mills, S Moffat, C White, AJ Newman Taylor
Occupational and Environmental Medicine, Imperial College of Medicine (NHLI), London, UK.

A prospective cohort study of childhood asthma and allergic disease based in SE England has been underway since 1993. A consecutive series of newly-pregnant women were recruited (93% of those eligible) and 642 babies were born. Information on patterns of wheezing was collected retrospectively at annual interviews; data up to age 3 was complete for 608 (95%). Occasional wheezing was reported by 40% mothers at age one, 28% at age two and 25% at age three. A small number of mothers (3%, 2% and 3% at each year) reported that their child always wheezed over the past 12 months. Wheezing (ever vs never) was more common in boys than girls and in families where the mother was more educated. After adjusting for these potential confounders, exposure to maternal cigarette smoke was a determinant of wheezing at age one (OR 2.01, 95% ci [1.34, 3.00]) age two (2.31 [1.55, 3.44]) and age three (2.06 [1.38, 3.10]). Increased family size was more strongly associated with earlier wheezing: OR 1.45 (1.21, 1.74) per sib at age one, 1.19 (1.00, 1.42) at age two, 1.12 (0.93, 1.35) at age three. A similar pattern was observed for the association between wheezing and sharing a bedroom. Parental asthma was less strongly associated with wheeze at age one (1.36 [0.93, 1.99]) than age two (2.22 [1.50, 3.28]) and age three (2.53 [1.70, 3.76]). The protective effect of breast feeding was also less strong at age one (0.77 [0.54, 1.09]) than age three (0.62 [0.42, 0.92]). These results suggest that wheezing in early infancy more closely resembles respiratory infections but as the child becomes older, patterns of wheezing become more similar to asthma.