Hello, and I hope I can help you today. At the age of 40 and above, 20 to 25% of pregnancies will end in miscarriage. The reason for this is that the number of genetically abnormal pregnancies increases significantly with age. When a very early pregnancy is not normal, sometimes it never even develops into a fetus which is called an early pregnancy failure. The most common sign of early pregnancy failure is abnormal increase in hCG values. As you probably know, hCG is supposed to double every two days in a normal pregnancy. Progesterone is produced by your ovary in the early part of pregnancy, so even with a normal progesterone level, it is possible to still have a pregnancy that will not result in development of a fetus. Unfortunately, there is absolutely nothing that can be done to prevent miscarriage. It is not really prudent to necessarily check your hCG every two days as long as you do not have any bleeding or pain. Testing of your pregnancy for viability can really not take place until your beta hCG value is as high as 1500 which is when the pregnancy should be visible on an ultrasound. Furthermore, taking extra progesterone can only help to keep the pregnancy inside, but it does not change the genetics of the pregnancy itself. So, in your case I would recommend waiting a while for checking another hCG value. If your hCG does not continue to rise, or if you develop any bleeding, it is unlikely that this is a pregnancy that will ever develop normally. Still, in the majority of cases, women can have successful pregnancies that are healthy even until their mid-40s. However, the chance of miscarriage is still quite high and sometimes a few miscarriages may be conceived before a woman is able to achieve a successful pregnancy. The fact that you were able to become pregnant is a positive sign and even if this pregnancy does not work out, it means that you are likely to conceive again and get another chance in the future. I hope I was able to adequately answer your question today, and that my advice was helpful. Best wishes for the rest of the pregnancy, Dr. Brown