”Have you had your oral exam yet?” This is what doctors remind women who are preparing to get pregnant when they go to the hospital for pre-pregnancy check-ups. Although oral examinations are not routinely included in preconception checkups, doctors are advising women preparing for pregnancy to visit the dentist for dental checkups because oral problems during pregnancy can have a very negative impact on the fetus. Some studies have reported that gingivitis during pregnancy is not common in all pregnant women, and the presence of no local irritation in pregnant women with good oral conditions does not cause gingivitis; while if a pregnant woman has periodontal disease it may lead to premature delivery or low birth weight of the baby, and if a pregnant woman has periodontal disease before pregnancy, it can be made more serious during pregnancy due to hormonal changes that encourage the growth of certain pathogenic bacteria. On the other hand, if a pregnant woman has difficulty eating due to toothache, it will lead to nutritional imbalance, which will indirectly affect the health of the fetus. Therefore, women who are planning to get pregnant should receive oral health checkups before pregnancy to establish a healthy oral environment, so as to avoid the treatment risks associated with oral emergencies during pregnancy. Careful dental treatment during pregnancy Expectant mothers should treat their teeth carefully, especially during early and late pregnancy, and it is best to choose to treat dental disease before pregnancy. This is because once a dental disease is present, there are certain risks for pregnant women, whether it is medication or invasive surgery. If a mother-to-be has dental discomfort in early and late pregnancy, she can ask her dentist to do temporary treatment, and if treatment is necessary, she should also treat it in mid-pregnancy. In early pregnancy, i.e. 1 to 3 months, is the trimester when the vital organs of the fetus are formed, and if X-ray examination is performed at this time, it may cause spontaneous abortion or malformed baby. Therefore, only some emergency treatment will be done at this time, and no overly complicated disposal will be done. In the middle trimester, i.e. 4~6 months, less invasive dental treatment can be done, and generally only local anesthesia is chosen to avoid general anesthesia. In late pregnancy, i.e. 7~9 months, only emergency treatment is also suitable, and traumatic oral surgery at this stage can easily lead to premature delivery of the baby.