Dear Niraj,
I would like to tell you that A teratogen is an agent that can disturb the development of the embryo or fetus. Teratogens halt the pregnancy or birth defect.

Following components acts as teratogen

1. ACE (angiotensin converting enzyme) inhibitors
2. angiotensin II antagonist
3. isotretinoin (an acne drug)
4. alcohol
5. cocaine
6. high doses of vitamin A
7. lithium
8. male hormones

I hope this information helps you

all the best