Malimplantation caused by trophoblastic insufficiency resulting in failure of gestation following in vitro fertilization-embryo transfer

In early abortions as well as in other cases of 'biochemical' pregnancies following IVF-ET, malimplantation occurs due to a primary deficiency of the trophoblast which affects decidualization and results in apparent malimplantation. Despite a possible immune involvement it does not seem that an immune rejection is taking place. Immune protection of the conception may not be initiated.