HCG doubling normal indicates that the embryo development is good, if the progesterone is low, there may be symptoms of preeclampsia, this is due to the progesterone fluctuation is relatively large in the early stages of pregnancy. Under normal circumstances, if it is within the normal range, the progesterone is not a problem, if the progesterone is lower than normal, usually the patient may have symptoms of preeclampsia, such as a small amount of vaginal bleeding or stomach pain, in this case must pay attention to as much as possible bed rest, reduce activities. If the progesterone is lower than 5ng/ml, this situation should be considered that the embryo is not well developed. Therefore, if you find that the progesterone is low and the HCG is normal, you should continue to observe, and if you have the condition, you can go to do ultrasound to check whether the development of the fetus is normal.