congenital abnormalities

Most single congenital abnormalities follow multifactorial
inheritance and carry a low risk of recurrence, but the safety of
scanning provides an ideal method of screening subsequent
pregnancies and usually gives reassurance about the normality
of the fetus. Syndromes of multiple congenital abnormalities
may follow mendelian patterns of inheritance with high risks of
recurrence. For many of these conditions, ultrasonography is
the only available method of prenatal diagnosis.