Rate of Growth in Relation to Birth Rank and Family Size.

Considerable attention has been given recently to the fact that average heights and weights for age tend to decrease as family size increases. As birth weights increase with parity up to the seventh or eighth child (McKeown and Gibson, 1951), it might have been expected that the average heights and weights of children in large families would be greater, rather than less, than those of only children, but the reverse seems to be the case. What has not yet been elucidated is whether all children in the large families show retarded growth or if some are more handicapped than others. Although Lowe and Gibson (1953) showed that later-born children had fallen behind the average for first-boms by their 3rd birthday, their group of first-borns were of necessity still either only children or the first of two, and the effect on the older children of subsequent additions to a family is not apparent from their study nor from that of Douglas and Blomfield (1958) reporting on the National Child Health Survey. Scott (1961, 1962) has analysed the material available from the London County Council records of heights and weights of school children measured in 1959, but this is cross-sectional data and no information was obtained about birth rank or about the rate of growth of the children concerned;