"Shengji'er" refers to how many weeks of gestation?

Generally speaking, a "viable fetus" refers to 17 weeks of gestation. The detailed analysis is as follows:

"Viable fetus" is a commonly used term indicating the survival capacity and developmental stage of a fetus. This concept is primarily used in assessing a pregnant woman's gestational period, especially for evaluating the risk of preterm birth. Definitions of fetal viability may vary depending on country and medical practice, but generally refer to the fetus's ability to survive and its level of development within the uterus. Gestational age is typically calculated from the first day of the mother’s last menstrual period (LMP), with pregnancy divided into 40 weeks. Using this method, the gestational age can be determined by calculating the number of days between the first day of the LMP and the current date. In general, fetal viability is considered to begin around 17 weeks. Determining gestational age is crucial for prenatal care management and preterm birth risk assessment. Generally, the more advanced the gestational age, the higher the fetus’s chances of survival and degree of development, and the lower the risk of preterm delivery. Conversely, when gestational age is smaller, the fetus's survival prospects and developmental maturity are relatively lower, and the risk of preterm birth is correspondingly higher. Based on different stages of fetal development, doctors can implement appropriate management and preventive measures. For example, during early pregnancy, physicians may recommend routine prenatal care and regular check-ups to ensure normal fetal development.

In cases where gestational age is small, pregnant women may be advised to take extra precautions, avoiding strenuous activities and unnecessary stress to reduce the risk of preterm labor.