Incidence of neurosis related to maternal age and birth order.

Order of birth and the strongly associated variable maternal age have often been investigated as possible determinants of a variety of congenital abnormalities. The work of Penrose (1934) and Malzberg (1950) on mongolism, and that of Still (1927) and McKeown, MacMahon, and Record (1951) on congenital pyloric stenosis has pointed to some of the difficulties. Birth order has also frequently been examined in studies of intelligence, juvenile delinquency, psychosis, and epilepsy, and after allowance has been made for the pitfalls in such investigations a general impression remains of a handicapping of the first-born. In psychiatric work, the emphasis shifts somewhat from the order of birth to the position in the family. This has long been looked upon as one of the influences moulding character. The schools of Freud and Adler in particular have always laid stress on this factor, and the tacit assumption has been made that it is also of aetiological importance in the production of mental and nervous disorder. If this is so, the decrease in mean family size from Victorian times to the present (from 5-71 to 2 19, vide Report of the Royal Commission on Population, 1949) may be important. Despite a wealth of anecdotal material there is a surprising paucity of recorded factual evidence. The present investigation attempts to answer the question whether the incidence of neurosis is related to maternal age and order of birth. The incidence of neurotic illness in only children, and in youngest, intermediate, and eldest children in families with more than one child, is also examined, as is the association with father's age, age differences between parents, and loss of one or both parents. Parts of this field have been surveyed in the last thirty years, particularly by Holmes (1921), Jones (1933), Thurstone and Jenkins (1931), Hsiao (1931), and Miller (1944), but much new material has been published since these reports were compiled.