Association of young and advanced age of pregnant women with the risk of isolated congenital abnormalities in Hungary - a population-based case-matched control study.

Objective: To analyze the possible association of maternal age with the risk of all congenital abnormalities (CAs) in a population-based large case-matched control data set.

Methods: The Hungarian Case-Control Surveillance of Congenital Abnormalities included 21,494 cases with isolated CA and their 34,311 matched controls. First the distribution of maternal age groups in 24 CA-groups and their matched controls was compared. In the second step, young (19 years or less) and advanced (35 years or more) age groups were compared. Finally, the subgroups of neural-tube defects, congenital heart defects and abdominal wall's CA were evaluated separately.

Results: A higher risk of gastroschisis, congenital heart defects, particularly left-sided obstructive defects, undescended testis and clubfoot was found in the youngest age group (19 years or less) of cases. The higher proportion of pregnant women with advanced age (i.e. 35 years or more) showed only a borderline excess in cases with clubfoot. The so-called U-shaped risk of maternal age distribution was found in cases with clubfoot and in the total group of isolated CAs.

Conclusions: The maternal age is a contributing factor to the origin of some isolated CAs mainly in young pregnant women.