Inflammation is a normal response of the body, but knowing what it is, why it happens, and its role on prenatal health can help prevent unnecessary complications.
What is inflammation?
According to The Harvard Medical School Family Health Guide, “Inflammation’s aim is to defend the body against bacteria, viruses, and other foreign invaders, to remove debris, and to help repair damaged tissue.”1 The inflammatory response is part of a broader immune response that has evolved to recognize and remove bacteria, viruses, and foreign invaders, in order to maintain health.
A wide array of events, from catching a cold to stubbing your toe, can initiate an immune response. Familiar signs of inflammation are swelling, redness, heat, and pain. Most people are familiar with these typical signs of inflammation when they occur in a localized manner as a result of physical injury. The focus of this article is on the more generalized inflammation that occurs in response to infection, which can be exacerbated by underlying risk factors such as stress, toxic exposures, diet, and exercise. This type of inflammation does not always, or even usually, manifest in an obvious manner, but can have deleterious effects during pregnancy.
Factors that cause or change inflammatory responses
- Pathogens Bacteria, viruses, and fungi initiate an immune response as the result of infection. Our bodies are in constant contact with these microbial organisms, some of which can become pathogenic and cause disease. The immune system often eliminates, or maintains a balance, without observable effect, but sometimes the microbes overwhelm our defenses and make us sick.
- Injury Physical trauma initiates an inflammatory response that is typically localized to the site of injury.
- Smoking Smoking is a toxic exposure that triggers an immune inflammatory response and is a major risk factor in the development of heart disease, chronic lung disease, and stroke.2
- Exercise Research has shown that muscles produce anti-inflammatory chemicals. They also work as part of the endocrine system to help work fluids that have seeped out of the vessels back into circulation. However, you have to be moving to get these benefits.3 Inflammatory responses are often exacerbated in people who do not exercise enough.
- Diet Processed foods, foods high in refined sugars, refined grains low in fiber like flour, white rice, pasta and pastries, dairy foods, trans-fats and hydrogenated oils, all negatively influence inflammatory response pathways.
- Environmental Toxins Besides smoking, environmental toxins such as mercury, aluminum, pesticides, BPHs in plastic, PBDEs in furniture, and PFOA in nonstick cook wear can all cause pro-inflammatory gene expression, which in turn alters normal immune responses.
- Stress Stress raises your body’s cortisol level. Cortisol is immunosuppressive and can alter or inhibit the immune response to viral infection.4 High maternal cortisol levels during pregnancy can have adverse consequences on the growth and development of the fetus.5
Carnegie Mellon University’s research team leader, Sheldon Cohen, did a study which “showed that people suffering from psychological stress are more susceptible to developing common colds.” The study also demonstrated that symptoms of the common cold are not caused by the virus but “are instead a ‘side effect’ of the inflammatory response that is triggered as a part of the body’s effort to fight infection. The greater the body’s inflammatory response to the virus, the greater is the likelihood of experiencing the symptoms of a cold,”6
Inflammation during pregnancy is a unique health risk
In recent years, much research has been published identifying and defining the adverse effects on fetal development caused by maternal inflammatory responses during pregnancy.7-13 Although influenza infection has been extensively studied 14,15,16 similar associations have been made with other infections including rubella, measles, varicella zoster, and diphtheria.17
Fetal brain development is adversely affected by maternal inflammation produced by the mother’s normal, immune system response to influenza infection. Interestingly, and of particular importance, active replication of the virus is not necessary for this damage to occur.18,19 It is the mother’s immune response to the pathogen, not the pathogen itself, that produces damaging developmental effects on the fetus.
This last point has been well-documented and is especially important with respect to treatment options to prevent infection. The influenza vaccine immunizes and prevents influenza infection by stimulating the immune system in the exact same manner as the infection itself. That is precisely the benefit of vaccination: it provides the stimulation of the same protective immune response as infection, but without the attendant symptoms of flu such as headache, nausea, and vomiting.
Yet, it is this immune response ̶ the normal, healthy, typically beneficial immune response ̶ of the mother during pregnancy, that is the cause of harm to the developing fetus. Vaccinating for flu doesn’t prevent this dangerous situation. Just like infection, it creates it.
Minimizing adverse inflammatory effects during pregnancy
- Influenza Many people suggest to avoid immune stimulation against the flu. This means avoiding both infection and vaccination since both cause an immune response, and it is this normal, protective immune response from the mother that causes the damaging inflammatory effects to the fetus. Keep in mind the odds. The probability of contracting influenza in any given year is in the range of 5%. 20 However, for those vaccinated during pregnancy, prenatal exposure of the fetus to the maternal immune response is guaranteed.
- Exercise According to Dr. Mark Hyman, family physician and eight-time New York Times best-selling author, “Mounting evidence tells us that regular exercise reduces inflammation. It also improves immune function, strengthens your cardiovascular systems, corrects and prevents insulin resistance, and is key for improving your mood and erasing the effects of stress. In fact, regular exercise is one among a small handful of lifestyle changes that correlates with improved health in virtually ALL of the scientific literature. So get moving already!” 21
- Relax Relaxation doesn’t just feel good. It makes your cells relax too! When you engage in relaxing activities like yoga and meditation, your immune cells release chemical messengers (cytokines) which tell your other cells to cool down inflammation.22
- Quit smoking Quitting smoking and avoiding second hand smoke can be one of the smartest ways to reduce inflammation, but it’s not always easy. A great resource to help you or your loved ones get started is Smokefree.gov.
- Eat healthy foods or at least eat healthier foods. Eating good whole foods can better support your immune system and help fight inflammation. Some of these foods are fatty fish, whole grains, vegetables (especially green leafy ones), fruits, and nuts.
Although the inflammatory process is part of a healthy, normally functioning and beneficial, immune response, certain factors can cause inflammatory pathways to lead to adverse health outcomes. Understanding these risks can help parents make informed decisions.
- Family Health Guide. (2006) What you eat can fuel or cool inflammation, a key driver of heart disease, diabetes, and other chronic conditions. The Harvard Medical School. Source
- Public Library of Science (PLoS). (2005). Smoking and Inflammation. PLOS: Medicine. Source
- Western Washington University. Inflammation. Source
- Role of early stress in the individual development in host response to viral infection. 2006. Avitsur et al. Brain, Behavior, and Immunity 20:339-348
- Effects of maternal prenatal stress on offspring development. 2008. Lazinski et al. Arch Womens Ment Health 1-13
- Carnegie Mellon University. (2012). How stress influences disease: study reveals inflammation as the culprit. Science Daily. Source
- Effects of prenatal infection on brain development and behavior: A review of findings from animal models. 2010. Boksa et al. Brain, Behavior, and Immunity 24:881-897
- Prenatal inflammation impairs adult neurogenesis and memory related behavior through persistent hippocampal TGFβ1 downregulation. 2010. Graciarena et al. Brain, Behavior, and Immunity 24:1301-1309
- Individual differences in maternal response to immune challenge predict offspring behavior: contribution of environmental factors. 2011. Bronson et al. Behavioural Brain Research 220:55-64
- Maternal immune activation causes age- and region-specific changes in brain cytokines in offspring throughout development. 2013. Garay et al. Brain, Behavior, and Immunity 31:54-68
- Maternal and developmental immune challenges alter behavior and learning ability of offspring. 2012. Grindstaff et al. Hormones and Behavior 62:337-344
- Maternal immune activation leads to activated inflammatory macrophages in offspring. 2014. Onore et al. Brain, Behavior, and Immunity 38:220-226
- Maternal infection and immune involvement in autism. 2011. Patterson et al. Trends in Molecular Medicine 17;7:389-394
- Maternal influenza infection during pregnancy impacts postnatal brain development in the rhesus monkey. 2010. Short et al. Biol Psychiatry 67:965-973
- Maternal influenza infection causes marked behavioral and pharmacological changes in the offspring. 2003. Shi et al. Journal of Neuroscience 23:297-302
- Gestational flu exposure induces changes in neurochemicals, affiliative hormones and brainstem inflammation, in addition to autism-like behaviors in mice. 2013. Miller et al. Brain, Behavior, and Immunity 33:153-163
- Maternal infection: window on neuroimmune interactions in fetal brain development and mental illness. 2002. Patterson et al. Current Opinion in Neurobiology 12:115-118
- Maternal influenza infection is likely to alter fetal brain development indirectly: the virus is not detected in the fetus. 2005. Shi et al. Int J Devl Neuroscience 23:299-305
- Activation of the maternal immune system during pregnancy alters behavioral and development of rhesus monkey offspring. 2014. Bauman et al. Biol Psychiatry 75:332-314
- Influenza vaccination: policy versus evidence. 2006. Jefferson. British Medical Journal 333:912-915
- Hyman, M. (2009). Is your body burning up with hidden inflammation? HuffPost: Healthy Living. Retrieved from Source
- Counter-stress effects of relaxation on proinflammatory and anti-inflammatory cytokines. 2008. Koh et al. Brain Behavior, and Immunity. 22:1130-1137