You can determine if you are pregnant by taking a blood test for HCG after 10 days of intercourse. If the HCG is greater than 5 mIU/ml and the value of progesterone is outside the normal range, it indicates a pregnancy. After this symptom, the HCG should be rechecked every other day. If the HCG doubles every other day, the gestational sac is well developed. If the value of progesterone rises steadily, it means that the fetus is developing normally. If the value of progesterone does not rise, but on the contrary, low, consider the possibility of miscarriage, should be timely supplementation of progesterone, you can take oral progesterone or dextroprogesterone, this kind of drug can supplement enough progesterone, play a role in preserving the fetus.