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Recurrent pregnancy loss is never easy, especially when it continues to occur during implantation. At Chicago-area’s Reproductive Medicine Institute, our experienced team has helped many patients through recurrent peri-implantation pregnancy loss. Peri-implantation pregnancy loss presents clinically as unexplained infertility and/or preclinical, occult or chemical pregnancy loss. There are usually no pregnancy symptoms, but a blood test reveals small amounts of the pregnancy hormone hCG in the mother’s blood. In a classic study by A.J. Wilcox in 1988, 22 percent of pregnancies diagnosed by a positive blood pregnancy test were lost around the time of expected menses.
Difficulties during implantation can be the result of an embryo not capable of implanting or a uterus incapable of responding to the invading embryo. Problems with the embryo can be contributed by either the sperm or the egg, and consist of abnormal chromosomes, genes, or DNA. Problems within the uterus that prevent completion of implantation after initial attachment involve interference with the processes of:
The migration of the embryo into the uterine lining is accomplished by proliferation of the invading cells of the embryo and the ability of these cells to digest a path through the uterine tissue. Proliferation of the invading cells is stimulated by proteins called growth factors secreted by cells within the uterine lining. Digestion of the path through the uterine tissues is accomplished by the same enzymes that are involved in dissolving clots (fibrinolysis). Thus, defects in production of growth factors or fibrinolysis result in peri-implantation pregnancy loss. Once the embryo has migrated into the uterus, two events need to occur to ensure success of pregnancy. The embryo must not be rejected by the maternal immune cells and the embryo must induce its own blood supply to get enough nutrients to continue to grow.
Since the embryo contains proteins contributed by the father, they will be foreign to the mother. Therefore, the mother must adapt her immune response so as to not reject or destroy the pregnancy. At the same time the maternal immune system has to “tolerate” the paternal contribution to the pregnancy, it must maintain anti-infectious immune responsiveness to protect both the mother and the embryo. Pregnancy has, thus, been thought of as a state of immunologic tolerance. This tolerance is induces by signals from the embryo to maternal immune cells. Such signals include secretion of a protein called soluble HLA G. Deficiencies in induction in tolerance can lead to pregnancy loss. Thus, immunologic causes for peri-implantation pregnancy loss include inadequate embryonic signaling for tolerance or inappropriate response of the maternal immune cells to proper embryonic signaling.
Pregnancy loss during implantation can result from lack of established blood supply to the pregnancy so that insufficient nutrients are available to support further growth of the embryo. From studies of cancer cells, we know that groups of cells can grow to a size of approximately 3 mm nourished by diffusion alone. But to exceed the 3mm size, the cells must recruit host blood vessels to provide nourishment for growth. The pregnancy reaches a size of 3 mm approximately 2 week after fertilization. If blood vessels are not induced, the pregnancy does not continue to grow. Lack of recruitment of blood vessels results from a defect in a process called angiogenesis. Angiogenesis is the formation of new blood vessels from preexisting vessels and is induced by proteins called cytokines. If cytokines do not stimulate angiogenesis so that the pregnancy can have its own blood supply, peri-implantation pregnancy loss will ensue.
Treatment of recurrent pregnancy loss during implantation is dependent on the cause. The treatments for recurrent pregnancy loss during implantation at our Chicago-area centers are the same as those for pre-implantation pregnancy loss, intravenous immunoglobulin and intralipid.
If you are suffering recurrent pregnancy loss, especially during implantation, you should consult one of our Chicago-area centers. Reproductive Medicine Institute has helped many patients conceive even after recurrent pregnancy loss. Please contact us today to schedule a personal consultation with one of our fertility specialists