At what week(s) do teratogens entered the birth mother's system, and what are the effects you can suspect from teratogens in her system?

Expert Answers
Karyth Cara eNotes educator| Certified Educator

The effects of teratogen occur when they enter the birth mother's system "the third to eighth weeks of pregnancy, when the major organ systems are forming." The effects on the fetus can be anatomical or neurological in nature and range from cleft palates to central nervous system malformations.