The role of both uterine natural killer cells uNK (cells) and peripheral blood natural killer cells remains controversial. A recent paper in the British Journal of Obstetrics and Gynaecology highlights the lack of uniformity in establishing normal ranges. Treatments available include intravenous haemoglobin or useful glucocorticoids such as Prednisolone. The results from glucocorticoids are at best inconclusive. Intravenous gamma globulin should not be used because of some serious side effects. The role of this treatment in recurrent miscarriage or recurrent implantation failure in IVF is uncertain.

Endometrial scratch is a treatment involving superficially scraping the lining of the womb in the hope that this will help embryos implant. There is some evidence that this may improve implantation rates. In a particular group of women, the effectiveness of this treatment on improving pregnancy outcomes in patients who have recurring miscarriages has yet to be evaluated. In both these areas of fertility research, much more work needs to be done.