I need to have my remaining teeth pulled during my pregnancy. Is laughing gas harmful to the fetus? Also, what pain meds after the procedure are safe

Yes . I would advise you to avoid the extractions until after your pregnancy is completed if possible. If you must have the extractions i would avoid nitrous oxide, usually, obstetricians allow tylenol (acetaminophen) for pain but the obstetrician should be consulted.
Precautions. You should not use laughing gas! have your dentist consult with your obstetrician so that you will know everything that you can and can't do. Congratulations and good luck!
Wait til later. If you are going to get any dental work i advise you wait until you are past the 1st trimester... As for pain meds..Best to check with your OB they each have their own opinions. And...Congrats! on the coming child.