Cervical insufficiency is often presented as painless dilation of the cervix，while the clinical manifestations of cervical insufficiency in the first pregnancy are more insidious. Cervical ultrasound detection for high-risk pregnant women can identify suspected cervical insufficiency at an early stage. There is no consensus among countries on the need for ultrasound cervical length screening for all women in their second trimester，but it is certain that the most important significance of universal screening is to detect high-risk women who are preterm in their first pregnancy and to prevent late abortion and preterm birth. Women with a history of second-trimester miscarriage or preterm birth but no reasonable indication of cervical cervix shortening（CL≤25mm）may benefit from cervical cerclage. In addition，the most important thing to target the cause of short cervix is to rule out the cervical changes caused by infectious factors. The significance of ultrasonic cervical examination after cervical cerclage lies in the individual decision-making according to the specific condition.

Cervical incompetence is a common pregnancy complication which is related to late miscarriage and spontaneous preterm birth. By analyzing the relevant studies in China and overseas，we systematically expound the potential pathogenesis of cervical incompetence and provide a theoretical basis for the prevention and treatment of cervical insufficiency.

Progesterone is a steroid hormone which plays an essential role in the menstrual cycle and implantation and at each step of human pregnancy. Since the synthesis of progesterone drugs，progesterone therapy has been used to prevent and treat implantation failure，miscarriage and premature birth，and is also used in cervical insufficiency. With the development of evidence-based medicine，although the evidence about the actual roles of progesterone have increased greatly， many controversies still remain. The purpose of this review is to summarize knowledge about the use of progesterone in cervical insufficiency.

Cervical incompetence during pregnancy is one of the important causes of mid-term pregnancy loss and preterm birth，which is a clinically diagnostic disease lacking objective gold standards.Cervical cerclage is the most effective method for treating cervical incompetence，but different surgical methods have varying treatment effects. This article aims to evaluate different surgical methods，providing reference for clinical practice.

With the rapid development of assisted reproductive technology and the advanced maternal age，the incidence of multiple pregnancies has increased significantly，among which twin pregnancies are the most common. Multiple pregnancies，including twin pregnancies，may lead to unique complications，such as twin- twin transfusion syndrome，twin anemia polycythemia sequence，twin reversed arterial perfusion sequence，selective intrauterine growth restriction，chromosomal abnormalities or developmental abnormalities in one of the twins，etc. Some of them require intrauterine treatments such as fetoscopy and fetal reduction during pregnancy，which increases the risk of miscarriage and premature birth. Cervical cerclage can repair the morphology of the cervical ostiation，and give cervical canal support. Cervical cerclage also can prevent the continuous expansion of the cervical ostium effectively，and help prolong the gestational age and maintain pregnancy. It remains controversial whether intrauterine treatment with cervical cerclage can reduce the risk of miscarriage and preterm birth. This paper aims at this problem and makes a summary based on relevant literatures at home and abroad.

Emergency cervical cerclage is an emergent surgery for the treatment of asymptomatic cervical dilation and/or amniotic protrusion in the second trimester and is widely carried out domestically and /or abroad. However，this surgery has certain technical difficulties and may be accompanied by complications such as premature rupture of membranes，chorioamnionitis，and cervical laceration. Obstetricians may have confusion about how to easily and effectively retract the protruded fetal membranes. They often face difficulties with evaluating the benefits and risks of the surgery and with accurately predicting the pregnancy outcomes. This article reviews the clinical evidence and key surgical points of emergency cervical cerclage，in order to provide reference for obstetricians to perform the surgery.