Does Pregnancy Alter the Brain’s Immune Function??

Recent research published in the November 2017 issue of Brain, Behavior, and Immunity suggests that a woman’s immune response in the brain may decrease during pregnancy and the postpartum period. These findings, discussed by the Brain and Behavior Research Foundation, might help to establish a connection between the brain’s immune function and the anxiety and mood disorders that are common throughout pregnancy and the postpartum period.

Previous research has shown that during pregnancy, the response of the body’s peripheral immune system (the part of our protective system that does not protect the brain) is suppressed. This is believed to protect the growing fetus from being attacked by the mother’s immune system. Most women don’t notice any effects from this suppression, though it is interesting to note that those who suffer with autoimmune disorders such as rheumatoid arthritis or multiple sclerosis might actually experience a temporary lessening of their symptoms at this time.

The researchers set out to determine whether these types of immune changes seen in the body might also occur in the brain. Using mice, they first injected both pregnant and non-pregnant mice with a chemical that typically elicits a strong immune response. They then measured the amount of inflammation in the brains of the pregnant mice as well as the control group mice.

Two areas of the brain that are connected with depression and anxiety — the hippocampus and the medial prefrontal cortex — were examined. Results showed that pregnant mice showed a reduced immune response in both of these regions, particularly during the later stages of pregnancy as well as into the postpartum period.

It is well known that the period of time around childbirth is associated with an increased incidence of anxiety and depression in mothers. Hormonal changes as well as immune function in the body have been linked to these illnesses. Now these recent findings concerning altered immune function specifically in the brain might help propel further research.

During pregnancy or postpartum, approximately one out of every seven women experiences significant depression, anxiety, obsessive-compulsive disorder, panic, or post-traumatic stress. Still others experience symptoms of bipolar disorder with its cycles of deep depression and periods of very high energy, decreased need for sleep, and changing moods (mania). And finally, postpartum psychosis (thankfully quite rare, occurring after one or two per thousand births) presents with serious symptoms including agitation and bizarre feelings or behaviors. The woman might be delusional, experience sensory hallucinations, and even harm herself or her baby. It is interesting to note that all these disorders can also occur with miscarriage, abortion, stillbirth and infant loss.The good news is that these illnesses are all treatable, so women who are suffering should seek help as soon as possible. My hope is that continued research will lead to a greater understanding of the hows and whys of all these perinatal disorders, so that fewer women will be affected by them.