Abstract: In the past, maternal mortality (MMR) was an important indicator of women′s health and socio-economic development in a country or region. In 2019, the U.S. Centers for Disease Control and Prevention collected information on maternal deaths across the country and concluded that up to half of all maternal deaths are preventable if action is taken. With the introduction of the millennium development goals (MDGS) in 2000 and countries′ emphasis on maternal health, maternal death has become a very low probability event, while the incidence of severe maternal morbidity (SMM), that is, the incidence of critical maternal events, has become a more common and useful indicator of obstetric care than mortality. For every maternal death in the United States, about 50 women experience SMM. Although MMR has traditionally been a key indicator of maternal outcomes, the prevalence of SMM can provide more comprehensive information on perinatal health and is a way to monitor maternal outcomes. At the same time, SMM is usually a precursor of maternal death, and as a dynamic process leading to maternal death and a preliminary indicator, it has important clinical significance for strengthening maternal management and thus reducing MMR. Many countries have begun to take the incidence of SMM as one of the important indicators to evaluate the quality of obstetrics. Controlling the occurrence and development of severe maternal morbidity can reduce maternal mortality. Prevention and control of SMM, in addition to conventional strategies, to avoid medically related delays, the use of maternal early warning trigger tool (MEWT) has important clinical value.

Key words: Maternal mortality；, Pregnancy, high-risk；, Maternal health；, Delayed Diagnosis；, Severe maternal morbidity