Although there exist a lot of agents that they can affect to the fetus during the pregnancy as the stress or the radioactive pollution, the drugs constitute a serious risk for the correct development of the fetus, including the legal ones. Any agent that causes a birth defect is named teratógeno.

On the one hand the woman who consumes drugs usually shows other factors of risk that damage the baby like a deficient maternal general state of health expressed by malnutrition, deficient prenatal assistance, major risk of infectious illnesses, serious psychosocial stress or toxicity for overdose.

But also the drugs consumption during the pregnancy is contra-indicated since it produces numerous anomalies and problems in the development of the fetus. These are the specific effects that can cause the drugs in the fetus during the pregnancy:

• Medicines without recipe: To take a medicine mistaken in the least suitable moment can cause a permanent physical anomaly in the fetus. (example: Talidomina on the 26th).
• Caffeine: Two cups of coffee or three refreshments a day increase l risk of premature childbearing, and of newborn baby with minor weight.
• Other medicines can produce effects: antibiotic, antidepressing, certain hormones...
• Alcohol: in excess: It can provoke the "Syndrome of fetal alcoholism" (facial malformations, defective members, face and heart). In general the alcohol in excess produces deficit atencional in children and minor development of height and cranial perimeter.
• Nicotine: The index of fetal death and neonatal it is major in smokers and the urine of the babies contains remains of the drug. The new-born mothers babies with está addiction retain the nicotine. In general, on having been born, the weight is minor. At present a possible relation is studied with the hyperactivity.
• Cocaine: Associated with minor weight and minor development of the cranial circumference, worse motor development at the age of two, less awake time to the month to be born, major excitability and minor quality of the reflexes. They are more inclined to neurological and cognitive problems.
• Marijuana: It can provoke minor attention, smaller babies and more problems of learning and memory.
• Heroine: It is related to severe disorders of the behavior, the babies are born addicted and show clear abstinence signs with quakes, irritability, disorders of the sleep and alterations motorboats. The symptoms can be supported up to one year after the birth. The attention deficit can be a perm.
• The amphetamine and metanfetaminas: They can increase the risk of abortion, premature childbearing and complications at the moment of the birth. The effects are not very well-known, for it it is surer not to use these substances during the pregnancy.

The danger of the structural defects caused by the teratógenos is major in the beginning of the embryonic development. This is the period of the órganogénesis (development of the vital organs) and it lasts approximately 6 weeks. The later damages, instead of causing structural damages, it is more probable that they could atrophy the growth or cause problems in the functioning of the organs.