When an embryo stops developing, the progesterone level will gradually decrease, but how much it can decrease is uncertain; it depends on the gestational age and individual differences. However, if an embryo stops developing, the progesterone level usually does not exceed 20. Therefore, during pregnancy, it is essential for pregnant women to maintain good living habits, avoid harmful factors, rest well, strengthen nutrition, abstain from sexual intercourse in early pregnancy, avoid misuse of medication, and be vigilant about symptoms like vaginal bleeding or abdominal pain.