I am so sorry to read about the heartbreak your friend would be going through. Has she had a uterine biopsy to check for natural killer cells? If she is under the care of a FS I guess they have done all the typical things like Sperm analysis, progesterone etc. Maybe she has really low levels of folate which causes recurrent m/c. 6 m/c can't be just bad luck. Maybe even a lap and dye might shed some light. A small fibroid or polyp which can not be seen on scan can act as an IUD and prevent either implantation or bub been able to grow properly in that environment. When I had my 3rd loss which was ectopic I had a lap to remove my tube and pregnancy and it was found that the tube was sick which caused me to m/c twice before. They said it was toxic which is what cause the prior m/c's. Once the tube was rmoved my next pregnancy resulted in my baby girl. So many possibilities. Sometimes the FS wont suggest certain investigations unless your friend pushes for them herself.