The properties of enteroviruses justify their consideration as possible causes of foetal damage: they are highly prevalent and cause infections which, although usually of minor severity, are often associated with viraemia. Of the enteroviruses, ECHO type 9 is of particular interest because of its periodic epidemic prevalence and the similarity to rubella of many of the infections it causes. Studies by Rantasalo, Penttinen, Saxen, and Ojala (1960) and by Kleinman, Prince, Mathey, Rosenfield, Bearman, and Syverton (1962) did not reveal unequivocal evidence of association between ECHO 9 virus infection during pregnancy and malformation of the infant born subsequently. The possibility that this infection may not cause foetal damage is also of importance to the clinician assessing the implications of a rubelliform illness during pregnancy, and to the epidemiologist evaluating the risk of congenital abnormality complicating "rubella" in studies in which an unknown proportion of maternal illnesses might have been due to ECHO 9 infection with fever, rash, and lymph-node enlargement. An epidemic of ECHO 9 infection in Glasgow in 1960 (Landsman and Bell, 1962; Combined Scottish Study, 1964) (1) They were insufficient in quantity or were anticomplementary and so were unsuitable for ECHO 9 antibody tests (350);(2) The outcome of pregnancy could not be traced because of change of address, or because the mother lived in areas beyond the city boundary, etc. (78); (3) Diagnosis of pregnancy not sustained (13).
RECORDSWomen were traced by means of laboratory specimen numbers, using a pre-arranged code which indicated the clinic attended. Ante-natal records were examined on the clinic premises and the desired information was transcribed onto punch cards. These records were those used in the normal conduct of the clinics. Questions regarding illness during pregnancy were not specifically directed towards possible ECHO 9 infection. None of the women was interviewed by us.Among the details entered on punch cards were the mother's age and parity, the date on which serum was obtained, and the duration of pregnancy at that date (calcuilated in weeks from the date of onset of the last menstrual period). For those attending the hospital clinics, details of each confinement were obtained from the obstetric units concerned. For those attending the Corporation clinics, the appropriate entry on the ante-natal 152 copyright.