Contractions at 33 weeks are a physiological phenomenon, and if they are obvious and other symptoms are present, they may also be related to preterm labor. 1. Physiological phenomenon: generally contractions start from the middle of pregnancy, 33 weeks belongs to the late stage of pregnancy, at this time the beginning of contractions and the enlarged uterus began to fall, increasing the pelvis to withstand the pressure related. Secondly, they may also be triggered by physiological factors such as overwork and emotional instability, which are normal physiological phenomena. 2. Preterm labor: the etiology of preterm labor is not clear, it may be related to infection, excessive dilatation of the uterine cavity, stress, multiple pregnancy, history of preterm labor and other factors. If a 33-week pregnant woman has obvious contractions, which slowly develop from irregular to regular contractions, and there is also a feeling of lower abdominal distension, abdominal cramps, vaginal discharge of fluid and other symptoms, it is necessary to suspect preterm labor. In conclusion, when a 33-week pregnant woman starts to have contractions, excluding physiological phenomena, she should go to the hospital in time to do the relevant examinations, to clarify the specific causes and then follow the doctor’s instructions to deal with treatment.