The duration of fetal preservation depends on the reason for which the pregnancy is being preserved, and the exact duration varies individually. For pregnant women with pre-eclampsia, they usually need to rest for at least one week, but the actual situation needs to be diagnosed by the doctor; for pregnant women with placenta praevia, they usually need to keep the fetus until about 37 weeks of gestation, and since placenta praevia is often accompanied by active bleeding, they should pay attention to rest during the period of fetus preservation; for pregnant women who have IVF, they usually need to rest in bed after the operation and give progesterone and other fetus preservation treatment for about 3 months before it becomes relatively stable. Therefore, there is no fixed time limit for fetal preservation, and the duration of fetal preservation may vary according to the condition of the pregnant woman. It is recommended that during the period of fetal preservation, pregnant women should review the ultrasound regularly, rest in bed, avoid strenuous exercise, keep bowel movements smooth, and prohibit intercourse.