Congenital defects in a cohort followed for seven years.

A geographically limited cohort of Finnish children was followed from birth for seven years, and all congenital abnormalities were recorded and classified and special attention was given to the cumulative detection rate, and the time of detection of various defects. Of 3674 pregnancies 135 babies with or without defects were stillborn or died during the neonatal period. The remaining 3539 were followed up to seven years, when the percentage follow-up was 81.7%. Detailed information on 76 malformed livebirths registered in the neonatal period was available in 63 cases (82.9%). The diagnosis was found to be incorrect in 6 cases and additional defects were registered in 7 of these children. Additional congenital abnormalities detected in the follow-up study were divided into three groups: all congenital disorders or abnormalities with prenatal etiology (248 children), all congenital defects (111 of these 248) and structural malformations (31 of these 111). The cumulative detection rates in these groups increased with time and at the end of the study when the children were aged seven were 9.4%, 5.6% and 2.6%, respectively.