Since Orshi brought it up in the Welcome thread, I thought it might be good for those of us who've had miscarriages to have a separate thread. I only have a quick second, but here's the info I have about what to think about to prevent miscarriages:
1. sometimes there's absolutely nothing to do for prevention, it was just a random loss that won't happen again.
2. if a woman has a history of repeat miscarriages, and/or family history of female relatives with miscarriages, or personal or family history of bleeding/clotting disorders, consider testing for common genetic mutation called MTHFR. That's a whole other topic!
3. TSH (thyroid stimulating hormone) levels should be checked if miscarriage with low basal body temperatures and/or other signs/symptoms of low thyroid function, like unwanted weight gain, hair loss, fatigue, constipation, dry skin. TSH should be 2.5 or less.
4. test serum progesterone, especially if woman has short luteal phases, and/or low basal body temperature. Easy to supplement with progesterone creams, suppositories, or oral. Adequate progesterone levels are required to maintain pregnancy in the first 10-12 weeks. Recurrent miscarriages in the first trimester may indicate the need for progesterone.
There's a lot more too say about each of these points, and I'm sure tons of other info out there, this is just a first pass.