Signs of preterm labor are as follows: 1. Uterine contractions with a feeling of tightness in the abdomen. It starts with irregular contractions and can develop into regular contractions with 4 or more contractions in every 20 minutes or 8 or more contractions in 60 minutes. 2. Small amount of vaginal bleeding; 3. Fluid (amniotic fluid) flowing or gushing out of the vagina in a watery manner, due to rupture of the pre-term fetal membranes; 4. Continuous back pain; 5. Cramping sensation in the lower abdomen or pelvis; 6. Mild abdominal cramps. If any of the above happens, the mother-to-be should come to the doctor early. After coming to the hospital, the doctor will tell the mother-to-be whether to be hospitalized and what to pay attention to in order to avoid preterm labor.