What is ADHD?

(continued)

Other Risk Factors for ADHD

Exposure to certain substances during pregnancy or when a child is very young may be associated with an increased risk of ADHD.

Risk factors during pregnancy include exposure to:²¹

• Tobacco, alcohol, and drugs
• Certain medications
• Methylmercury from mother’s fish consumption¹⁷

Other risk factors during pregnancy include the mother’s high blood pressure, a low vitamin D level, and stress, as well as early (pre-term) birth and lack of oxygen during birth.^{17, 22}

Low birth weight and brain injuries may also increase the risk of a child developing ADHD.¹⁷

Some factors in the environment are believed to increase the risk of ADHD. Just like with genes, however, no single cause can explain all cases of ADHD.⁹

Environmental factors that may contribute to the risk of developing ADHD include:

• Exposure to environmental toxins, especially lead, at a young age^{21, 23}
• Poor nutrition and limited human contact for children¹⁷