Age at diagnosis of birth defects.

Background: Many birth defects surveillance programs ascertain cases of birth defects diagnosed beyond 1 year of age. The Western Australian (WA) Birth Defects Registry includes cases diagnosed up to 6 years of age, but the value of extending ascertainment beyond 1 year has not been assessed.

Methods: We examined the age at diagnosis for all cases and all birth defects notified to the WA Birth Defects Registry for births and terminations of pregnancy in 2000 and 2001 and estimated the amount of person time needed to ascertain cases diagnosed beyond 1 year of age.

Results: Of the 3294 cases of birth defects, 616 (18.7%) had at least one birth defect diagnosed prenatally, 1574 cases (47.8%) were first diagnosed by 1 month of age, 671 infants (20.4%) were first diagnosed with a birth defect from 1 month up to 1 year, and 400 cases (12.1%) were first diagnosed between 1 and 6 years of age. Two thirds of children diagnosed with Fetal Alcohol Syndrome, and one quarter of those with congenital hearing loss were diagnosed beyond 1 year of age. We estimated that it took 1.76 person weeks work per annum to ascertain cases diagnosed between 1 and 6 years of age.

Conclusions: One in eight cases of birth defects were ascertained beyond 1 year of age. We consider that the additional work required to include these cases in Western Australia is outweighed by the benefit of more complete ascertainment.