HCG doubling slow, progesterone drop there are two possibilities: 1, intrauterine pregnancy, but the quality of the embryo is not good: intrauterine pregnancy embryo development is not good and ectopic pregnancy is identified by doing ultrasound, do ultrasound in the uterine cavity has a gestational sac, and then you can determine that it is an intrauterine pregnancy, if there is no gestational sac in the uterine cavity, the uterus outside of the gestational sac, to determine that it is an ectopic pregnancy; 2, ectopic pregnancy: if the days of cessation of menstruation is relatively early, the HCG doubling slow, progesterone value is low, this time is not recommended for birth control, because intrauterine, extrauterine is not sure, if it is an ectopic pregnancy to take birth control measures, it is not good for the body, more likely to lead to the rupture of the extrauterine gestational sac, which can easily lead to hemorrhage, is very dangerous.