Pregnancy is the happiest thing for women, but some women always have preterm labor during pregnancy, in fact, preterm labor during pregnancy is not without reason, therefore, to avoid the occurrence of preterm labor, you should understand the cause of the disease, and early good measures to prevent preterm labor. 1, patients with a history of multiple miscarriages. The first thing you need to do is to get a good idea of what you are getting into. Some women are too nervous once they are pregnant, or have excessive emotional fluctuations to some unexpected stimuli, too violent emotional fluctuations can cause excessive contraction of the uterus, causing preterm labor; 3, disease factors. During pregnancy, pregnant mothers do not pay attention to personal hygiene, or their own existence of vaginitis or cervicitis without thorough treatment, or the occurrence of gestational diabetes can affect the normal development of the fetus, which can also have an impact on the fetal membranes, causing premature rupture of the fetal membranes, resulting in preterm labor. 4, the cervix after surgical treatment. Such as conization and other cervical surgery, will cause the shortening of the cervical canal, prone to preterm delivery. 5, the fetus and placenta factors. If the fetus is too large, twin pregnancy, premature abruption of fetal membranes, placenta praevia, placental insufficiency, etc., in order to ensure the safety of the mother and child, it will also artificially cause the fetus to be born prematurely. Therefore, there are many causes of preterm birth, women must have balanced nutrition, relaxation, quit smoking and alcohol during pregnancy, and actively carry out prenatal care, not only for personal safety during pregnancy, but also for the health of the fetus.