An ICBDMS collaborative study: monitoring multimalformed infants.

Multimalformed infants (MMI) without a diagnosis of a specific syndrome have often been successfully used by alert clinicians to prompt studies which have led to the definition of new teratogens. However, usually they are not analyzed in any specific way in the routine monitoring by birth defects registries. In 1980 the International Clearinghouse for Birth Defects Monitoring Systems (ICBDMS) decided to try to develop new methodologies to use MMI in the larger and more systematic context of birth defects monitoring. Before starting the following issues had to be addressed: (a) definitions of "single defect" and of "multimalformed infant", (b) transmission of information, and (c) coding. Only those registries able to give detailed descriptions of defects could take part. Between January 1983 and December 1987, out of more than 6.5 million births from 19 registries, 3,534 infants with at least three unrelated defects of any type were centrally registered and coded by a single person. Three main monitoring procedures were used: (a) statistical analysis of the frequency of 58 types of defects observed among the MMI, (b) computer aided search for "similar cases", and (c) identification of "non random associations" and comparison with appropriate baseline material. This last procedure can also be used in cumulated material to study some well-known associations such as "VATER". These monitoring activities did not identify any "alarm" situation, however, many simulations have shown the efficiency of the procedures, as well as the possibilities and limits of this collaborative monitoring activity.