A teratogens  is an agent that can cause  or increase the chances of a birth defect. It is usually something in the environment that the mother has been exposed to during pregnancy . It could be a prescribed medication , a street drug , alcohol use , chemical exposure or an infection present in the mother. All of these can increase the risk of a baby being born with birth defect.

What are the most sensitive  periods of teratogen in pregnancy ?

After conception , it takes about  6 to 9 days for the  egg  to implant in the uterus. After implantation, a common blood supply exist between the mother and the embryo. Something in the mother’s blood can cross over to the developing fetus. For example, for teratogen to interfere with the closure of the neural tube, the exposure should occur between 3.5 to 4.5 weeks of pregnancy. There are some organ systems that are sensitive to teratogens throughout pregnancy  such as the central nervous system. This includes the brain and spinal cord. Alcohol is one teratogen which affects the central nervous system. Use of alcohol anytime during pregnancy has the potential to  cause birth defects  and health problems in a baby because the central nervous system is sensitive to teratogen throughout all the nine months of pregnancy. That is why it is important to avoid alcohol consumption completely during pregnancy .

The are lots of different potential teratogens that exist. Seek the advice of your health  care provider.