Cervical Mucus may contain many answers.

New literature has gone back to square one and looked at all the possible protiens , cytokines, antibodies in the cervical mucus of women that suffer from recurrent pregnancy loss. There were proteins identified that when present at high levels were actually embryotoxic and regardless of how the patient conceived (i.e. IUI or IVF) these led to early losses. There were antibodies present in these high risk women against their husbands sperm and as we had known and it was shown again , these women had a difficult time conceiving with natural relations as the antibodies would attach to the head of the sperm and make penetration into the egg more difficult. Lastly there was a correlation between the levels of the "inflammatory cytokines" in the cervical mucus and the risk of pregnancy loss, many of the inflammatory cytokines discussed on this website were looked at and the cervical mucus is just another source of information to be studied.

So even though we may bypass the cervical mucus with IUI or IVF we may still need to step back and take a look as it might reflect the environment in the uterine cavity where the embryo needs to implant.