Can cervicitis from untreated yeast infection cause stillbirth at 33 weeks pregnant?

Probablly not, but..: Both yeast and cervicitis are common in pregnancy, but yeast is rarely a cause of cervicitis. Most likely your baby is in no danger at all, but you need to discuss this with your obstetrician. Good luck!

Separate issues: It is not clear form your post whether you dad a miscarriage or worry about one. A yeast infection is a localized lower tract issue that does not enter the blood or attack baby. Baby is walled off from this by location & surrounding fetal membranes. It's only exposure would come during delivery. Stillbirth can result from a variety of issues but this is not one of them.