OBSERVATIONS RELATING TO THE AeTIOLOGY OF PATENT DUCTUS ARTERIOSUS

In a recent investigation of 633 cases of congenital heart disease it was noted that the incidence of patent ductus arteriosus appeared to be higher in first-born than in later-born (MacMahon, 1952). The number of affected (48) was rather small, however, and it seemed important to confirm the observation on a larger series. In the present communication data are recorded on 166 cases of patent ductus arteriosus; it is shown that affected boys are more common among first-born than among later-born, and affected girls are more common among children of young mothers than of older mothers. In view of the association of incidence with maternal age and birth order we have looked for other evidence of environmental influence, and it is noted that (a) there is a marked seasonal fluctuation in the number of affected girls (but not of boys), and (b) a history of foetal distress at birth was recorded in a considerable proportion of cases. The possible significance of the last observation is discussed in relation to experimental work on the mechanism of closure of the ductus.