Every family wants to have a healthy baby, and pre-pregnancy check-ups are often paid attention to, but among a series of check-ups, the oral cavity is often neglected. When a pregnant woman with a big belly visits a dentist, after the doctor informs her of the treatment plan and medication, she is often worried that the treatment or medication will have an impact on the child in her womb, and that not treating it will also affect the child for fear of aggravating the disease. Don’t neglect the oral cavity for preconception checkups. So before preparing for pregnancy, it is recommended to have an oral system examination. First of all, check whether there are wisdom teeth in the mouth, the eruption of wisdom teeth is mostly between 18 – 30 years old, overlapping with the pregnancy period, the mandibular wisdom teeth mostly can not be fully erupted, far in the visible blind pocket, easy to accumulate food, nourishing bacteria, causing local inflammation or interstitial infection, it is best to pull out before pregnancy. Secondly, check whether there are cavities (tooth decay), residual crowns and residual roots in the mouth. The change of diet and hormone level during pregnancy can easily cause acute pulpitis or apical inflammation, which will not only produce severe pain, but also affect the fetus if medication is not used carefully. With the progress of research, it is found that the untreated dental caries in the mouth of pregnant women can spread the pathogenic bacteria to the child. Therefore, before pregnancy, for the caries and the residual crown and root, if it can be treated, it should be treated; if it cannot be treated, it should be extracted. Finally, we need to check the gum and periodontal, with the arrival of pregnancy, the level of estrogen is rising, which often leads to gingivitis and even gingival tumor, research confirms that women who do not suffer from gingivitis before pregnancy, the proportion and severity of “gingivitis in pregnancy” are greatly reduced after pregnancy; while those who suffer from gingivitis or periodontitis before pregnancy Women who had gingivitis or periodontitis before pregnancy will have more severe inflammation after pregnancy, with gums becoming enlarged, swollen, bleeding significantly, and in severe cases, preventing eating. In addition, the toxicity of bacteria in the patient’s periodontal pockets increases and the damage to periodontal bone tissue is aggravated, often causing the loosening and loss of multiple teeth. Therefore, examination and systematic treatment of gingivitis and periodontitis should be performed before pregnancy.