定义和发生率根据国际妇产科学会(FIGO)规定,月经期正常((3-5天)/(28±7天)),末次月经日期确实的孕妇,妊娠期限超过42周(>294天),称为过期妊娠. 过期妊娠的胎儿在妊娠和分娩过程中,容易发生胎儿窒息,造成死亡,增加围产期死亡率和新生儿发病率,被列入高危妊娠. Definition and Incidence According to the FIGO guidelines, menstrual periods were normal (3-5 days) / (28 +/- 7 days)), pregnant women with the last menstrual date were pregnant for more than 42 weeks (> 294 days ), Known as outdated pregnancy.Over premature fetus during pregnancy and childbirth, prone to fetal asphyxia, resulting in death, increased perinatal mortality and neonatal morbidity, was included in the risk of pregnancy.