Causes of birth Defects Genetic/Chromosomal% Environmental(teratogens)-10-15% Combined-20-25% Multiple gestations-1% Unknown%Causes of Birth Defects ▪ Genetic/Chromosomal - 15-20% ▪ Environmental (teratogens) - 10-15% ▪ Combined - 20-25% ▪ Multiple Gestations - 1% ▪ Unknown - 40-50%