Genetic factors (genetic mutations), physicochemical factors (exposure to herbicides, rodenticides, trichloroethylene, trichloromethane, radiation, respirable particulate matter, PM10, nitrogen dioxide, carbon monoxide, ozone), adverse lifestyle habits during pregnancy such as alcohol abuse, smoking and passive smoking, biological factors (viral infections in early pregnancy such as toxoplasmosis, rubella virus, cytomegalovirus, herpes simplex virus, coxsackievirus and microviruses), pharmacological factors (antiepileptic drugs, antidepressants, angiotensin converting enzyme inhibitors), psychological and disease factors (extreme mental stimulation or prolonged stimulation of the mother during pregnancy can also cause abnormal embryonic heart development).