What is the main cause of physical and mental defects birth rate even exceeds those of spina bifida and Down syndrome? What drug makes a fetus suffers severe abnormalities that cause the heroin, cocaine or marijuana? The answer to both questions is the same: alcohol. In the United States, alcohol (wine, beer or liquor) is the most common preventable cause of birth defects. When a women drinks alcohol during pregnancy risks giving birth to a baby who will pay the consequences, with mental and physical, for the rest of his life. Still, about ...