• R J Rona, M C Gulliford, and S Chinn.
• Department of Public Health Medicine, United Medical School, Guy's Hospital, London.
• BMJ. 1993 Mar 27;306(6881):817-20.

ObjectiveTo determine whether birth weight and gestational age are associated with respiratory illness and lung function in children aged 5-11 years.DesignCross sectional analysis of parent reported birth weight, gestational age, and respiratory symptoms; parental smoking and social conditions; forced vital capacity (FVC), forced expiratory volume in one second (FEV1), forced expiratory rates between 25% and 75% and 75% and 85% (FEF25-75 and FEF75-85), and height.SettingPrimary schools in England and Scotland in 1990.Subjects5573 children aged 5-11 (63.3% of eligible children) had respiratory symptoms analysed and 2036 children (67.1% of eligible children) had lung function measured.Main Outcome MeasuresSymptoms of asthma, bronchitis, occasional and frequent wheeze, cough first thing in the morning, and cough at any other time and lung function.ResultsBirth weight adjusted for gestational age was significantly associated with all lung function measurements, except FEF25-75. The association remained for FVC (b = 0.475, 95% confidence interval 0.181 to 0.769) and FEV1 (b = 0.502, 0.204 to 0.800) after adjustment for gestational age, parental smoking, and social factors. FEF75-85 was the only lung function related to gestational age. Respiratory symptoms, especially wheeze most days (adjusted odds ratio 0.9, 0.84 to 0.97) were significantly associated with prematurity. Every extra week of gestation reduced the risk of severe wheeze by about 10%.ConclusionsLung function is affected mainly by intrauterine environment while respiratory illness, especially wheezing, in childhood is related to prematurity.

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