India, April 7 -- M any infertile couples face the challenge of failing IVF cycles despite having normal uteruses and good embryos. The reason lies at the molecular level - a concept known as 'endometrial receptivity', which cannot be detected by ultrasound. The uterus is most receptive to accepting the embryo during a short period of 24-36 hours called the 'Window of Implantation (WOI)'. Any shift in this window due to hormone changes or chronic inflammation may lead to IVF failure. The Endometrial Receptivity Analysis (ERA) test detects any shift, and personalised embryo transfer is a strategy to address this issue, but the reliability and benefit of this test are still in question. Platelet-rich plasma therapy is another novel therapy which acts at a molecular level to improve endometrial receptivity. The immune system also plays a major role. A strict balance between helper cells and cytotoxic cells is required for implantation, and any imbalance will lead to IVF failure. Various immunological tests and targeted immune therapies are suggested to restore this balance, but all these therapies are still largely experimental. In the absence of proven strategies to improve endometrial receptivity, conventional treatment of repeated IVF failures remains largely to treat any uterine infection or pathology, optimise hormonal synchronisation and improve endometrial thickness and blood supply. But these specialised tests and novel therapies can be attempted in these patients to give them the best chances of success. She can be contacted at 958-246-9429....