Miscarriage Causes: Immune Mechanisms

The fetus contains foreign genetic material coming from the father, but in normal circumstances it does not get rejected. However, in some women the immune system may reject the fetus and cause a miscarriage either by being high in numbers or by abnormal hostile activity. There are several immune disorders:-

Raised TH1/TH2 Cytokines

What are Raised TH1/TH2 Cytokines?

For years, conception of Th2 overbalance during pregnancy has been a paradigm for immunology of reproduction, while Th1 activity has been presented as unwanted component. Studies concerning Th1/Th2 balance in physiological and complicated pregnancy have been reviewed. Th1 activity during early peri-implantation period, premature and term labour not only accompanies but even predominates over Th2 activity.

Th1 activity plays an important role in the promotion of Th2 response, regulation of placentation process, defence against infections and initiation of delivery. Together with Th2 activity it is a necessary component of immunological reactions during pregnancy.

Many miscarriages and failed assisted conception events are caused by, or associated with, abnormal levels of cytokines, which are proteins secreted by white blood cells to control the inflammatory process in the body. The activity of these cytokines can be broken down into two categories: pro-inflammatory (or Th1) and anti-inflammatory (Th2). Early exposure to pro-inflammatory cytokines is necessary to stimulate the invasion of the blastocyst and the formation of new blood vessels during implantation. However, if the exposure to pro-inflammatory cytokines is excessive or prolonged, it can actually be severely detrimental to the pregnancy, and result in a failed implantation and early miscarriage.

New medical literature has also shown that an overbalance of Th17, another inflammatory cytokine, can result in recurrent pregnancy loss. There are many new cytokines in both the Th1 and Th2 category that we, at the Centre for Reproductive Immunology and Pregnancy, now test for not only inside of the T-cells and NK cells but in the serum surrounding all of the blood cells.


Most immune drugs such as steroids, hydroxychloroquine, IVIG and others can help suppress an overactive TNF alpha. However, Humira has been shown to very effective in these circumstances.