Association of birth weight with adult lung function: findings from the British Women's Heart and Health Study and a meta-analysis.

BACKGROUND: The aim of this study was to examine the associations between birth weight and lung function in a cohort of women aged 60-79 years and to combine these results with those from other published studies in a systematic review and meta-analysis. METHODS: The associations of self-reported birth weight with adult lung function (forced expiratory volume in 1 second (FEV1), forced vital capacity (FVC) and forced expiratory flow rate during mid expiration (FEF(25-75)), all measured using standard procedures, were assessed in a cross sectional study of 2257 British women aged 60-79 years. A detailed literature search was used to identify all published studies of the association, and meta-analysis was used to pool the results from our study and all published studies. RESULTS: There were positive linear associations between birth weight and all three measures of lung function in simple age and examining nurse adjusted regression models. However, with adjustment for height (squared), all three associations attenuated towards the null: adjusted (age, nurse, height2) change in FEV1 per 1 kg birth weight was 0.01 l (95% CI -0.02 to 0.04); in FVC was 0.02 l (95% CI -0.02 to 0.07), and in FEF(25-75) was 0.00 l (95% CI -0.04 to 0.04). Further adjustment for life course socioeconomic position, adult body mass index, and smoking did not alter these associations. The results were similar among life long non-smokers and those who had ever smoked. A meta-analysis of eight studies of adults suggested that there was a positive association between birth weight and FEV1: pooled increase in FEV1 per 1 kg in birth weight 0.048 l (95% CI 0.026 to 0.070) adjusted for age, smoking, and height (or height squared). There was no evidence of small study bias in this meta-analysis. CONCLUSIONS: There is a modest positive association between birth weight and lung function which indicates that intrauterine factors might have a role in lung development.