Go see a Dr.
I'm pretty sure it would hurt the baby more from the nicotine vs. the stress, but that's definatly a question you need to ask your Dr. on the next visit.
If you DON'T quit smoking though, you set you baby up for a future of cancers and they'll be born addicted to nicotine. Your child will have to overcome addiction alongside of being new to the world.
I used to try to justify it.... I decided to quit before I ended up getting pregnant.
*I'm honestly not trying to be self righteous, just genuienly helpful*