Why are therapies for unexplained miscarriage and infertility sometimes considered controversial?

Therapy for recurrent miscarriage is considered controversial because the studies did not agree on what to do. Some studies showed positive outcome for the immune therapy and some studies showed negative outcome or no benefit. And, because the studies that give it to unexplained recurrent miscarriage, so obviously ,you give immune therapy to somebody who does not have immune problem. And you don't expect positive outcome. So the studies or the reviews showed that if you give the immune therapy to patients who have immune system imbalance, and if you give it at the right time before pregnancy happens, you get a positive outcome. If you give the treatment after pregnancy happens, the effect is weak or weaker. And if you give it to patient with unexplained infertility, you can't see the positive outcome because you diluted your group. So if a patient have chromosomal abnormality, why on earth we give her immune therapy? Or if a patient has problem with the uterus, what immune therapy? How immune therapy will improve that? So you need actually to select your patients before you can judge. If you give anything to unexplained problem, you don't expect to find a good outcome.