In a population-based study in children born alive during the 10-year period from 1982 to 1991 (n = 22,810), ventricular septal defects (VSDs) were diagnosed in 127 cases, an incidence of 5.6 per 1000. The incidence was significantly higher in the cohort of children born during the 6-year period from 1986 to 1991 than among those born in the preceding 4-year period, 1982-1985 (6.5 and 4.0 per 1000 respectively; p 0.05). More children born in 1986-1991 had spontaneous closure of their VSDs (75.5%) than those born in 1982-1985 (51.5%) (p