Progesterone is normal if it is above 25ng/mL at the beginning of pregnancy, i.e. 30-40 days. However, the secretion of progesterone is not constant, it is pulsatile, so sometimes it is high and sometimes it may be lower when the test is done. If it is below 15ng/mL, the embryo may also develop normally, or it may stop developing or have a preterm miscarriage, or it may be the cause of an ectopic pregnancy. If progesterone is below 6ng/mL in early pregnancy, the pregnancy is unsuccessful. If it is below 10ng/mL, the success rate of pregnancy is also very low.