Physical agents:

One of the most serious is ionizing radiation, which causes growth retardation and defects of the central nervous system. Also it is necessary to mention the negative effects of vibrations.

Chemical agents:

• Pharmacs: cytostatics, antibiotics (especially tetracyclines and streptomycin), hormones (progesteron, androgens), antiepileptics, anticoagulants etc.
• Drugs: alcohol — with a cca 40% probability, chronic alcohol abuse during pregnancy causes fetal alcohol syndrome (characterised by brain damage — microcephaly, hydrocephaly, leptomeningeal heterotopy, corpus callosum agenesis, arinencephaly; heart defects — especially atrio-ventricular septal defects; growth retardation, congenital malformations of eyes and joints.)
• LSD, marijuana
• Smoking: leads to disorders in afterbirth adaptation, lower birth weight and increases the risk of pre-term delivery. Children whose mothers smoked during pregnancy also develop asthma more often.

Biologic agents:

The fetus can be negatively affected by any illness the mother undergoes during her pregnancy. Etiologic agents with the most serious effects on the fetus are listed below (however, the listing is not complete).

• Viruses: cytomegalovirus, herpes simplex, varicella-zoster, EBV, influenza, mumps
• Bacteria: treponema pallidum
• Parasites: toxoplasmosis