There are many reasons why a woman may experience a sudden drop in progesterone during pregnancy. If the sudden drop is measured once in a while, it may be related to emotions and exertion, or it may be caused by measurement errors, and can be rechecked again after 1 week. If the progesterone still drops, it may be related to embryonic abortion, pre-eclampsia or ectopic pregnancy, etc. It is necessary to clarify the reasons for the drop in progesterone and take corresponding treatment measures. 1. Embryonic abortion: Generally, if the intrauterine gestational sac or yolk sac persists for more than 2 weeks and still no fetal heart is seen, or if the average diameter of the gestational sac is 2.5-3cm and still no fetal heart is seen, or if the previous fetal heart disappears and the fetal bud length is 5-7mm and still no fetal heart is seen. Consider embryonic abortion, embryonic abortion can be manifested as a sudden drop in progesterone, generally should be timely clearance; 2, pre-eclampsia: early pregnancy abdominal pain, accompanied by vaginal bleeding, may be pre-eclampsia abortion, at this time can be manifested as a sudden drop in progesterone, to timely supplementation of progesterone for fetal preservation treatment; 3, ectopic pregnancy: B ultrasound does not see the intrauterine gestational sac, to further check the blood HCG, blood HCG more than 2500-3000U/L, consider ectopic pregnancy. If the blood HCG exceeds 2500-3000U/L, ectopic pregnancy is considered, and ectopic pregnancy sometimes also shows a decrease in progesterone; 4. Biochemical pregnancy: although there is an increase in HCG at the early stage, HCG and progesterone values can drop after the fertilized egg fails to implant.