Preterm birth refers to childbirth occurring between 28 and 36 weeks plus six days of pregnancy. The signs of preterm birth include the following aspects.

First, regular contractions occur, generally defined as four contractions within 20 minutes or eight contractions within 60 minutes.

Second, there may be a small amount of "show," mainly due to minor bleeding caused by the separation of the fetal membrane from the uterine wall.

Third, many women experience a significant feeling of heaviness in the lower abdomen, which is caused by the descent of the fetal head.

Fourth, upon examination, it can be found that the cervical canal has shortened and the cervical opening has dilated.

When the above symptoms occur, there should be a high suspicion of the risk of preterm birth, and medications should be used promptly as an intervention to try to avoid the occurrence of preterm birth.