If there is localized severe redness, gingivitis may have developed at these sites. After improving oral hygiene, gingivitis can heal again. If the redness persists, consult a dentist for an examination and advice.
If there is generalized severe redness that occurred in a short period despite good oral hygiene, see your dentist.
Please note that during pregnancy, there is a greater tendency for gingivitis due to hormone changes. Pregnant mothers should pay special attention to oral hygiene at home and have a dental checkup during pregnancy.