Several environmental agents—teratogens—can cause damage during the prenatal period. These include prescription and nonprescription drugs, illegal drugs, tobacco, alcohol, environmental pollutants, infectious disease agents such as the rubella virus and the toxoplasmosis parasite, maternal malnutrition, maternal emotional stress, and Rh factor blood incompatibility between mother and child. There are many statistics which prove the effects of the aforementioned substances. A leading example of this would be that, in America alone, approximately 100,000-375,000 'cocaine babies' are born on an annual basis. This is a result of an expectant mother abusing the drug while pregnant. 'Cocaine babies' are proven to have quite severe and lasting difficulties which persist throughout infancy and right throughout childhood. The drug also encourages behavioural problems in the affected children, as well as defects of various vital organs.