Regarding progesterone, there is no evidence that low progesterone
causes miscarriages; more likely low
progesterone levels during miscarriages reflect rather than cause an abnormal pregnancy. There is a condition called luteal phase defect (low progesterone) which has long been suspected to be associated with recurrent miscarriages. Treatment is progesterone medication. The problem is, there is no proof that luteal phase defect exists, or that adding progesterone helps.