Birth Weight and Subsequent Risk of Asthma: A Systematic Review and Meta-Analysis

BackgroundPrevious studies suggest that birth weight is related to later risk of asthma. However, few meta-analyses have investigated these associations. Therefore, we performed a meta-analysis with different classifications to further validate the relationship between birth weight and asthma.MethodsPubMed (1990-2013), ScienceDirect (1990-2013), EMBASE(1990-2013),EBSCO (1990-2013) and Springer (1990-2013) were searched for articles. The following MeSH terms were used: “birth weight”, “fetal growth retardation”, “intrauterine growth restriction”, “asthma”, “wheezing”.ResultsWe included 18 studies with data from a total of over 90,000 children and adults. (1) Low birth weight (<2,500 g) as compared with BW > 2,500 g and BW = 2500–4000 g was associated with increased risk of asthma (Children: OR, 1.28; 95% CI, 1.09–1.50, P < 0.05; OR, 1.34; 95% CI, 1.13–1.60, P < 0.05, Adults: OR, 1.25; 95% CI, 1.12–1.39, P < 0.05; OR, 1.25; 95% CI, 1.12–1.40, P < 0.05). (2) High birth weight (>4,000 g) was not associated with the risk of asthma when BW < 4,000 g and BW = 2500–4000 g were used as the reference.ConclusionsThese results suggest that low birth weight (<2,500 g) is associated with increased risk of asthma both in children and adults and may serve as a mediator between prenatal influences and later disease risk; but high birth weight (>4,000 g) was not associated with increased risk of asthma.