It is normal for progesterone to drop on 55 days of pregnancy when the fetal buds and heart are normal. A normal heartbeat on the 55th day of pregnancy indicates that the fetus is within the normal range of development, and the drop in progesterone at this time may be due to testing errors or normal fluctuations in hormone levels in the female body during pregnancy, which are physiological factors and do not mean that the growth and development of the gestational sac has been affected. Progesterone is a natural progesterone secreted by the corpus luteum of the ovary, which is necessary to maintain pregnancy. It is released in the body in pulses and may fluctuate at different times of the day. Fetal heart and buds are generally a stage in the development of the embryo. The normal appearance of fetal heart and buds indicates that the embryo is developing well. Pregnant women are advised to go to the hospital for regular checkups. The development of the fetus is not stable on the 55th day of pregnancy, so you must pay attention to rest and do not do too strenuous exercise or heavy work.