Objectives: To describe the clinical and subclinical characteristics and comment on some associated factors of mothers who gave preterm birth at Thai Nguyen National Hospital in 2021 - 2022. Subjects and methods: A cross-sectional descriptive study of 155 mothers who gave preterm birth at Thai Nguyen National Hospital from January 2021 to December 2022. Results and conclusions: Pregnant women have a combination of symptoms: Abdominal pain accompanied by bleeding or amniotic fluid or vaginal discharge when admitted to the hospital accounted for the highest rate (67.1%). Women with cervical dilation of 1 - < 3 cm when admitted to the hospital accounted for the highest rate (49.7%). Women with oligohydramnios account for 29%. Pregnant women with urinary tract infections when admitted to the hospital accounted for a high rate of 63.2%. Some factors associated with preterm birth are: gestational age at which the mother stops working and number of antenatal care visits, with statistical significance p < 0.05