Pregnancy is an incredible journey that transforms a woman’s body in numerous ways. One of the most vital changes that occur during pregnancy is the alteration in the immune system of the body.
The immune system, which is responsible for protecting the body from external threats like infections and diseases, modifies itself to enable the growth and development of the fetus during pregnancy. Through this article, we will explore the various immune system changes that occur during pregnancy.
What Is the Immune System?
The immune system is a complex network of cells, tissues, and organs that work together to protect the body from various infectious diseases, harmful organisms, and foreign invaders like bacteria, viruses, and fungi.
The immune system is divided into two parts- the innate and the adaptive immune system.
Innate Immune System
The innate immune system is the first line of defense against infectious diseases and involves physical and chemical barriers like the skin, mucous membranes, and antimicrobial substances like saliva and tears.
The innate immune system is non-specific and helps to eliminate pathogens through phagocytosis, a process in which immune cells engulf and destroy the pathogens by releasing digestive enzymes and toxic chemicals.
Adaptive Immune System
The adaptive immune system, as the name suggests, is highly adaptive and specific and responds to particular pathogens that the body has already encountered.
The adaptive immune system involves the production of antibodies and immune cells known as T cells and B cells that recognize and destroy specific pathogens. The adaptive immune system also has a memory that enables it to remember the specific pathogen that has infected the body and mount a faster defense response in case of a future infection.
How Does Pregnancy Affect the Immune System?
The immune system is known to undergo significant changes during pregnancy, which is essential to support the growth and development of the fetus inside the womb.
The immune system changes involve both the innate and adaptive immune system and are essential for the successful completion of pregnancy.
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Impact of immune system on pregnancy
Changes to the Innate Immune System
The innate immune system undergoes various changes that are focused on protecting the mother and the developing fetus.
Pregnancy leads to the suppression of various responses of the innate immune system like reduced local inflammation in the uterus, decreased cytokine production, reduced complement activity, and decreased natural killer cell activity. The reduction in these immune responses helps to prevent any immune-mediated damage to the developing fetus and promotes its growth and development inside the uterus.
Changes to the Adaptive Immune System
The adaptive immune system also undergoes various changes during pregnancy that are designed to promote maternal tolerance towards the fetus and ensure its survival inside the womb.
The maternal immune system recognizes the fetus as a semi-allograft, meaning it has foreign antigens from the father, and therefore does not mount a full-scale immune response against it. The changes that occur in the adaptive immune system during pregnancy include increased production of T regulatory cells that suppress the maternal immune system and allow the growth and development of the fetus.
The production of interleukin-10(IL-10) and transforming growth factor-beta(TGF-beta) also increases during pregnancy, resulting in a decrease in T cell proliferation, cytokine production, and antibody responses against fetal antigens.
Pregnancy and Susceptibility to Infections
Despite the immune system changes that occur during pregnancy, pregnant women are still susceptible to infection and are at an increased risk of developing severe infections like influenza, pneumonia, and urinary tract infections.
This increased susceptibility to infections is because the immune system is focused on promoting maternal tolerance towards the fetus and is less capable of mounting a robust defense against external threats. Additionally, some infections like cytomegalovirus, toxoplasmosis, and listeriosis can cross the placenta and infect the fetus, leading to miscarriage, stillbirth, or congenital disabilities.
Conclusion
The immune system plays a vital role in maintaining the health of the mother and the developing fetus during pregnancy.
The immune system undergoes a significant number of changes to promote maternal tolerance towards the fetus and ensure its growth and development. However, despite these changes, pregnant women are still susceptible to infections and must take precautions to protect themselves and their developing fetuses.
