Effects of prematurity and intrauterine growth on respiratory health and lung function in childhood

Rona RJ, Gulliford MC

1993

Primary schools in England and Scotland

The objective was to determine whether the birth weight and gestational age are associated with respiratory illness and lung function in children aged 5-11 years. 5,573 children had respiratory symptoms analysed, and 2,036 children had lung function measured. Reduced lung function was associated with low birth weight regardless of whether the child had respiratory complications at birth. Respiratory symptoms, especially wheeze, were significantly associated with prematurity. Every extra week of gestation reduced the risk of severe wheeze by about 10 percent.

As in many studies relating an adult condition to birth size, birth order has not been taken into consideration. Yet birth order is the best known single factor influencing birth weight. For example according to a British calculation the average difference in birth weight between first born and second born children is 138 grams. (see Odent M., Tsujino J., Studies exploring health in relation to intrauterine life should look at birth order, BMJ 1997; 314:1416)