About 10 % of the birth defects are caused due to environmental factors. The risk identification for exposure to such factors is of paramount importance as this form of birth defects can be prevented to a large extent if appropriate caution is taken. The environmental factors can be classified into 3 broad categories namely: chemical, biological and physical. Chemical sources include drugs and substances such as alcohol and cigarette. Biological agents include the various microorganisms and physical factors comprise of heat, radiation etc which, can affect the baby.