How to improve IVF implantation rates?

This review looked at treatments for women who have had multiple cycles of in vitro fertilization (IVF) without a pregnancy. It found that there are multiple options that may improve implantation rates, including white blood cell infusions or factors which grow the lining of the uterus.

IVF is a widely used infertility technique that involves collecting eggs and transferring the fertilized embryo(s) to the uterus. Implantation occurs when the embryo attaches to the lining of the uterus. It is normal for not all embryos to implant. However, some women experience repeated lack of implantation following multiple IVF embryo transfers.

An embryo has foreign cells with different genetic material from the woman. It is the immune system’s job to determine whether foreign cells are from an embryo, from friendly bacteria which normally live in the uterus, or from harmful pathogens. Peripheral blood mononuclear cells (PBMCs) include several types of white blood cells of the immune system and can be collected during a blood donation. These PBMCs are involved in how receptive the uterine lining is. PBMCs behave differently when there are pregnancy hormones such as human chorionic gonadotropin (hCG).

There are a variety of potential treatments for repeated lack of implantation. Some treatments affect the immune system. Other treatments affect the lining of the uterus, or the embryo itself prior to transplant. It is not clear which treatments are effective for improving implantation.

This review included 41 studies of treatments for repeated unsuccessful IVF implantation. All of the patients had at least 3 previous embryo transfers (ET) which did not result in implantation.

One treatment is to collect the woman’s PMBCs from a blood sample. These white blood cells can be infused into the uterus during the ET. Women who received PMBCs had birth rates 2.41 times higher. The hormone hCG, which alters PMBCs behavior, also improved birth rates.

Platelets are parts of the blood responsible for clotting. Platelet-rich plasma (PRP) may promote the lining of the uterus. Two studies found PRP may improve pregnancy rates by 2.45 times.

Granulocyte colony-stimulating factor (G-CSF) is a hormone which encourages certain tissues to grow. G-CSF is involved in the growth of the lining of the uterus. Significantly more women given a G-CSF injection became pregnant (2.29 times higher).

Intentionally damaging the lining of the uterus is thought to cause the growth of newer, healthier tissue. Three studies randomly assigned half of the patients to this treatment. They did not find a clear benefit to damaging the uterus.

Five studies looked at freezing embryos and using genetic testing prior to the ET. They found that genetic testing did not improve pregnancy or birth rates.

This review found that PMBCs and G-CSF are promising treatments for women with repeated lack of IVF implantation.

Some of these treatments need larger studies. Also, some studies were not randomized, meaning that women who had the treatment could have different medical histories from those who did not.