top of page

Pregnancy and the Immune System. The Miraculous Nature of Gestation.

When researching for this edition of Holistic Living Magazine focused on the Immune system, I found some fascinating information pertaining to the interrelation and connectivity between the maternal and foetal immune systems during pregnancy.

Here is a list of 6 interesting facts regarding Pregnancy and the Immune system.

1.A mother’s uterus should technically reject and regard their developing baby as foreign – but it doesn’t.

During gestation, the maternal immune system develops what is known as a tolerance to the foetus. Immune tolerance in pregnancy, otherwise referred to as “gestational maternal immune tolerance” is the absence of a maternal immune response against the foetus and the placenta. It is this tolerance that explains why the mother doesn’t reject the growing baby even though by nature it contains the genetic material of the father and should therefore be considered a foreign entity. Maternal immune tolerance is a unique example of how the immune system adapts what would normally be a destructive response to a state of tolerance.

2. The placenta forms an immunological barrier and a remarkable communication organ between mother and baby

The placenta is attached to the lining of a mother’s uterus as well as to the baby’s umbilical cord. It begins to form in week 4 of pregnancy and continues to develop over the next couple of months coming fully “online” to support the developing baby at around 12 weeks of gestation. One of the placenta’s main roles is to allow the transfer of nutrients and oxygenated blood from the mother to the baby; it also disposes of the baby’s waste back to the mother. This system is referred to as the placental circulation.

The placenta also produces hormones and builds a defense system that acts as a shield for the baby, providing protection against many types of bacteria and infections. This process involves transferring antibodies from the maternal blood supply to the foetal circulation; it is this process that gives the foetus passive immunity that can provide effective protection from specific infections.

The mother delivers this amazing temporary organ, soon after the baby is born in what is known as the third stage of labour.

3. The hormones of pregnancy can provide temporary remission from some chronic conditions.

Maternal tolerance may help explain why some autoimmune disease symptoms are lessened in pregnancy. Autoimmunity occurs when the immune system launches an inflammatory response against your own body. Psoriasis is a chronic autoimmune skin disease that speeds up the growth cycle of skin cells, it is characterised by the formation of red and crusty patches and silvery scales or plaques. Many women report a significant improvement in their psoriasis during pregnancy; a 2005 report attributed this improvement to the increased levels of oestrogen relative to progesterone during pregnancy. Expectant mothers with Multiple Sclerosis can also see their symptoms vastly improve or even disappear, particularly in the second and third trimesters. Finally, many women with Rheumatoid Arthritis report significant relief from joint pain during pregnancy.

The mechanisms of these immune modifications in pregnancy are still being studied and typically, the pregnancy doesn’t usually provide a permanent cure for these conditions, which generally return fairly soon in the postpartum period.

4. Foetal stem cells can repair the mother during pregnancy and male DNA can even be found in the brain decades after they have given birth!

It is now commonly recognised that during pregnancy, the placenta enables a two-way transfer of immune cells between mother and baby. This process is known as “foetal microchimerism”. Foetal cells exhibit a remarkable ability to migrate across the placenta into the mother and to integrate with diverse maternal tissues and organs, where they are able to target sites of damage and disease and have been found to persist for years, probably for a lifetime, in the circulation of normal women. DNA from male babies can cross the blood brain barrier, which becomes more permeable in pregnancy and enter the mother’s brain, where it can remain for decades.

A study of pregnant mice published in 2011 found that when a pregnant mouse has a heart attack, her foetus donates some of its stem cells to help rebuild the damaged heart tissue. Doctors have also observed that women who experience weakness of the heart during pregnancy or shortly after giving birth have better recovery rates than any other group of heart failure patients.

The old adage “you will always find a piece of me in your heart” couldn’t be more true with the knowledge of this amazing pregnancy phenomenon!

5. Normal vaginal delivery involves the seeding of the baby’s microbiome and the subsequent development of their lifelong immune system.

The human microbiome contains the genetic material of all the microbes-bacteria, fungi, protozoa and viruses that live on and inside the human body. The majority of these microbes live in our gut, particularly in the large intestine and current research suggests that between 70-80 percent of our immune tissue lies within our digestive system. It was once thought that babies in utero were in a completely sterile environment, but it is now commonly known that mothers do transfer gut microbiota via the placental circulation. In the weeks and days leading up to birth, specific species of good bacteria are migrating to key locations in the mother’s body and are transferred to the baby during and immediately after birth via the birth canal, exposure to faecal bacteria, immediate skin-to-skin contact after birth and with the initiation of breastfeeding. This process kick starts the colonization of the baby’s gut with bacteria from the mother and it is those microbes that have the earliest and most significant influence on the development of the baby’s immune system and helps to protect the infant from disease for its entire lifetime!

6. Breast milk is nature’s first immune booster!

Colostrum is an early form of milk that babies receive in the first few days after birth; it is rich in immunological components such as secretory IgA, lactoferrin, leukocytes and oligosaccharides or sugars. These sugars in breast milk function as prebiotics for the bacterial strains of the baby’s microbiome and effectively provide the fuel for the foundational gut microbiota to colonise and proliferate. As babies get older, leukocytes in breast milk naturally wane if everybody is healthy, but when an infection appears, leukocyte levels in the breast milk come firing back again to support the baby’s immune system.

Interestingly, the immunity that breast milk imparts, it seems, may depend in part on a mixture of milk and baby saliva flowing upstream. The material contained in the baby’s backwash may actually cause a mother’s body to create made-to-order immune factors that are then delivered back to the baby in milk. Through this backwash, the baby may be effectively placing an order that helps a mother’s body manufacture germ specific and uniquely ordered milk, very clever indeed!

bottom of page