Objective: To describe the seasonal growth patterns in Shanghai infants, to explore seasonal time lag between weight gain and length gain, and to investigate the long-term effect of birth season on early postnatal growth. Design: Community-based longitudinal study. Setting: Shanghai, People's Republic of China. Method: Children were followed up monthly from 1 to 6 months, 3 monthly from 6 to 12 months, and 6 monthly from 12 to 24 months. Subjects: A total of 6018 children born between 1 January 1980 and 31 December 1990. Main outcome measures: Weight gain, length gain and change in body mass index (BMI) over the seasons of the year. Results: The infants tended to grow faster in height in spring and summer, and faster in weight and BMI in autumn and winter. The seasonal effect on weight gain and length gain is largely independent. The mean length value at 1 month of age was about 2.0 cm higher in infants born in May to July than in those born in November to February. At 24 months of age this difference was reduced to about 0.7 cm. Conclusions: There is a clear and consistent seasonality in growth in Shanghai infants. The seasonality seems to act independently on weight and length. Birth month has some association with attained size, but this is reduced during the ®rst 2 y of life. Sponsorship: Children's Hospital

The aims of this study were to describe secular changes in body size in Shanghai infants, to compare the growth pattern between Shanghai children and Swedish children, and to explore the association of growth rate with parental body size, feeding practice and child health status. The study series consisted of 6,018 longitudinally followed full-term children, born between 1st January 1980 and 31st December 1990 in Fenglin Community, Shanghai. The data clearly show a positive secular trend in growth in Shanghai over the decade of observation; at 12 months, the mean increase in weight and length were 0.32 kg and 0.64 cm, and at 24 months they were 0.54 kg and 1.29 cm. The general growth pattern observed in the children in comparison with the Swedish reference was of fast growth in the first few months of life, and faltering between 9 and 24 months of age. Age at introduction of solid food, weaning age and parental body size were related to growth velocity in the first two years. There was little cumulative effect of diarrhoea on growth in the first two years of life.