IVF And The Immune System

In a typical IVF cycle, eggs are collected, embryos are produced and transferred back into the uterus. Pregnancy does not always occur. When this happens, it is tempting to speculate that the body is “fighting off the embryos” in some fashion presumably by using its immune system. It is only natural to think in this fashion. Typically, couples are presented with good embryos which are transferred to this black box (the uterus). When the embryos do not implant, is it not logical to think it is the uterus in some way fighting off the embryos? It may seem reasonable, but it is not true!

First some basic biology. If we study reproduction of couples with normal fertility, we find that the embryo implants in 1 of 6 cycles only! In the remaining 5 of 6 cycles, the embryo stops developing and is reabsorbed by the body. There is good evidence to say the uterus is an innocent bystander. Studies both in vivo and in vitro show that for a variety of reasons human embryos are very fragile and often arrest in their development. This is why we usually transfer more than one embryo.

If you look on the Internet, you will find many sites which tell you that immune problems can cause you not to get pregnant for IVF and you “should be tested”. The weight of the evidence is against this. The American Society of Reproductive Medicine recently published a committee report titled: “Antiphospholipid antibodies do not affect IVF Success”. The following is a direct quote:

“Controversy exists regarding a possible association between immune abnormalities and in vitro fertilization failure. The proposed mechanism of such failure includes abnormal implantation, placentation, and early embryonic vascular compromise. Intravenous immunoglobulin (IVIG) and antithrombogenic therapy including aspirin and heparin have been proposed as treatments in the expectation of improving implantation or placentation.”

The committee conducted a literature search and identified 16 studies on the matter. Their conclusions are as follows:

“None of the studies revealed a significant effect of the presence of antiphospholipid antibodies on IVF success. The assessment of antiphospholipid antibodies is not indicated among couples undergoing IVF. Therapy is no justified on the basis of existing data.”

Two recent articles in the October issue of Fertility and Sterility appeared supporting this view. The first was written by Dr Hornstein at Harvard: “Antiphospholipid antibodies in patients undergoing IVF: the data do not support testing”. The second was with Dr Hill from the same institution who wrote: “there is no proof that antiphospholipid antibodies cause infertility.” for more information please visit the ASRM web site: http://www.asrm.org

There is general agreement that in some cases antiphospholipid antibodies and lupus anticoagulant can cause miscarriages. Investigation is warranted if 3 or more miscarriages have occurred. We do not usually investigate for less than 3 because miscarriages are very common and usually due to chromosomal errors. These antibodies however do not cause infertility. Also remember that treatment for these antibodies is expensive and carries significant risks. Heparin which is commonly used is a blood thinner and has been associated with some complications.

Please understand we want to do everything that can help to establish a pregnancy. We do not want to do things which will not help and possibly harm the patient because they are suggested by some web sites on the Internet.