Abstract: The fetus at the gestation of 24 to 28 weeks is defined as a viable child. The rate of miscarriage at 24-28 gestational weeks in China was about 0.3% in 2011. The causes of threatened abortion occurring at 24-28 gestational weeks include fetal structure abnormalities, chromosomal abnormalities, abnormal uterine development, disorder of cervical function, infection, immunity and thrombosis, etc. Those pregnant women should undergo a systematic review of medical history, physical examination and ultrasonic examination. Since the etiology is closely related to infection, some new inflammatory factors are potential markers of premature birth and miscarriage, such as C-reactive protein, melatonin α and IL-6. In addition to the traditional methods of preventing uterine contractions, anti-infection, anti-coagulation, glucocorticoid and cervical ligation, new immunotherapy has also been reported. This paper reviews the research progress of threatened abortion occurring at 24-28 gestational weeks.

Key words: Abortion, threatened, Fetus, Premature birth, Infection, Therapy