The immune system is vital for health and most women have an immune system that’s in a state of relative balance and able to adapt for the changing needs of a pregnancy, however it’s quite possible many people have hidden immune problems as testing is costly, difficult to access or simply unavailable in many parts of the world.
It’s thought that imbalances in the immune system are part of the reason many couples struggle to conceive (especially those with ‘unexplained infertility’) as pregnancy requires major adjustments in the woman’s immune system to accommodate and support what are essentially foreign cells within it. This is because the placenta and embryo aren’t 100% her own, as half the genetic material (shown by proteins on the cell walls) come from the father, so the maternal immune system needs to recognise these abnormal cell proteins, and then act to protect the embryo before its removed by a ‘normal’ immune response.
By far the majority of immune challenges are experienced by our digestive systems, and rather strangely it’s recently been found that having certain types of round worm in the gut actually increases fertility; probably because the body’s immune reaction to other non-self cells (such as an embryo) is reduced when it also has to deal with the worms.
The initial investigations in routine cases of infertility don’t include testing the immune system as there are other more obvious and pressing reasons that should be considered first, but when the usual causes of infertility have been ruled out (blocked tubes, hormonal problems, male factor etc), and especially for couples who’ve had repeated miscarriages or repeated IVF failures, the status of immune system becomes a more significant question, although older couples should bear in mind the added complication of a natural increase in miscarriage from the age-related rise in chromosomal abnormalities. For women in their late 30’s the causes of infertility or miscarriage are thought to be:
- Chromosomes (40-50%)
- Blood clotting (20-25%)
- Other causes (25-40%)
Chromosomes have a randomness to them that’s less likely to cause repeated problems, however the other causes (including blood clotting) can be considered immune based because either:
- The mother’s immune system identifies egg or foetal cells as non-self and attacks them in the same way it would a viral, bacterial or parasitic invader
- The blood supply to the developing embryo is compromised by clotting factors, which are often immune based
These imbalances in the immune system are present for many couples who experience an inability to conceive naturally, repeated IVF cycle failures, or miscarriages.
- In many of these cases the female immune system either attacks eggs in the ovary, the developing embryo in the fallopian tubes or at the implantation site and any of these prevent pregnancy
- Where women have 3 repeated miscarriages with the same partner, an unbalanced immune system in one or both of the parents is usually thought to be the cause
- Repeated miscarriage affects less than 1% of couples but account for 2-5% of all pregnancies
It’s estimated that:
- 60% of women failing 4 or more IVF cycles have an immune related cause
- 30% of couples who try unsuccessfully to conceive naturally for 3 years have an immune related cause
A 2012 review considering the impact of immune factors on reproduction concluded:i
“Substantial evidence suggests that antiphospholipid antibodies, lupus anticoagulant, antisperm antibodies, antithyroid antibodies, anti-endometrial antibodies, antiovarian antibodies, anti-C trachomatis antibodies, cytokines, and immunological events in endometriosis and premature ovarian failure due to immunologic factors may contribute to reproductive failure including unexplained infertility and/or non-chromosomal recurrent miscarriage.”
Of course without doing testing, a couple with immune related infertility will never know there’s an issue, and simply join others with a diagnosis of ‘unexplained infertility’. Advances in science are throwing more light on the role of the immune system in fertility, including how it determines the integrity of the DNA of the eggs and sperm, the function of the ovaries (in both phases) and in the receptiveness of the endometrium for implantation (when 70% of IVF failures occur); what’s becoming increasingly clear is that the immune system plays a constant and vital role in both creating and maintaining life.
“In normal pregnancy a woman’s body accommodates what is essentially a foreign body that should be destroyed by her immune system.”
“The immune system is balanced in between a Th1 “autoimmune” and Th2 “suppressive” response and most women have a balanced system.”
“Women with implantation failures or recurrent miscarriage are unbalanced. They are too Th1 activated with cells that attack their pregnancy.”
Alan E Beer MD