BACKGROUND: Previous observational studies have claimed that birthweight and childhood wheezing disorders are associated although the results remained inconsistent. One systematic review and two systematic reviews that included meta-analyses reported inconsistent results. We aimed to conduct a systematic review and meta-analysis to investigate this. METHODS: An online search of published papers linking childhood asthma and wheezing disorders with birthweight up to February 2014 was carried out using EMBASE and Medline medical research databases. Summary odds ratios (OR) were estimated using random-effects models. Sub-group meta-analyses were performed to assess the robustness of risk associations and between-study heterogeneity. RESULTS: A total of 37 studies comprising 1,712,737 participants were included in our meta-analysis. The unadjusted summary ORs for risk of childhood wheezing disorders associated with low birthweight (<2.5kg) were 1.60 (95% CI: 1.39 to 1.85, P<0.001) and 1.37 (95% CI: 1.05 to 1.79, P=0.02) when compared with ≥2.5kg and 2.5-4.0kg birthweight groups respectively. The overall summary OR for high birthweight (>4.0kg) as compared to the 2.5-4.0kg birthweight group was 1.02 (95% CI: 0.99 to 1.04, P=0.13). There was substantial heterogeneity in the unadjusted low birthweight risk estimates which was not accounted for by predefined study characteristics. There was no significant heterogeneity in the high birthweight risk estimates. There was some evidence of funnel plot asymmetry and small study effects in the low birthweight (2.5kg versus ≥2.5kg and <2.5kg versus 2.5-4.0kg) odds ratio estimates. CONCLUSION: Our results suggest that low birth (<2.5kg) is an independent risk factor for wheezing disorders during childhood and adolescence although there was substantial heterogeneity among the risk estimates. However, we found no significant association of high birthweight with wheezing disorders.
CORE (COnnecting REpositories)
CORE (COnnecting REpositories)