Doomed to miscarry at 41 w/ infertility history? 2 kids by hmg+iui. Dec pg w/ miscarry. Again pg.

No. Miscarriage is higher at 40 and older, about 30-50%. A lot of these loses are due to chromosomal abnormalities. Progesterone support may be helpful since mature patients run lower Progesterone levels. Aspirin 81mg/day has also been found to thicken the endometrial lining and increase uterine blood flow to possible help implantation.
Aneuploidy. Women with miscarriages should be evaluated for aneuploidy. Most miscarriages are caused by an abnormal embryo. There are effective treatments for this. Seek an expert's help.
No. Odds of miscarrying are most directly related to age if a woman is in her 40s and has no other risk factors for pregnancy loss. There is a higher risk for chromosomal anomalies, and that should be discussed with a genetic counselor or perinatologist. Plus there are some conditions that occur more often in midlife moms, eg, diabetes, preeclampsia. Having gone through this, i'll write more on it.
No. Odds of miscarrying are most directly related to age. The older you are the more likely you are to miscarry. Early miscarriages in older moms are most likely due to a chromosomal abnormality, but if you have had 2 or more losses you should seek the care of a re/i for a evaluation of other causes of miscarriages that may be correctable. Good luck!
No. The reasons why women miscarry are many. Having one miscarriage does not increase your chances of miscarrying again. However, a woman who has had 3 consecutive miscarriages may have a medical condition causing this. A woman who needs to have fertility treatment in order to conceive should not be 'doomed' to miscarry, especially if she has carried pregnancies in the past.
No. You are not doomed to miscarry. Actually the odds are in your favor based on what you have told me. Your chances of miscarriage are higher though.
Yes. Low Progesterone in 1st trimester means that there is either something wrong with the pregnancy, or production of progesterone. From the ovary. Very often supplemental Progesterone will help. In a woman of 40+ usually there is a chromosomal defect, and a miscarriage will occur. I suggest screening both partners for chromosomal defects; if normal give Progesterone from ovulation.