Table of Contents > Allergies > Newborn immune system Print

Newborn immune system


Related Terms
  • Allergies, allergy, antibodies, antibody, bacteria, bacterial infection, breast milk, breastfeeding, colostrum, fibronectin, food allergy, Ig, IgA, IgD, IgE, IgG, IgM, immune, immune defense system, immune reaction, immune response, immune system, immunoglobulin, immunoglobulin A, immunoglobulin D, immunoglobulin E, immunoglobulin G, immunoglobulin M, infant, infection, interferon, microorganism, mammary gland, mucin, lactoferrin, lysozyme, milk lipids, pathogen, peanut allergy, vaccination, vaccine, virus, viral infection.

  • A baby's immune system is not fully developed until he/she is about six months-old. In the meantime, pregnant mothers pass immunoglobulin antibodies from their bloodstream, through the placenta, and to the fetus. These antibodies are an essential part of the fetus's immune system. They identify and bind to harmful substances, such as bacteria, viruses, and fungi that enter the body. This triggers other immune cells to destroy the foreign substance.
  • Immunoglobulin G (IgG) is the only antibody that crosses the placenta to the fetus during pregnancy. IgG antibodies are the smallest, but most abundant antibodies, making up 75-80% of all the antibodies in the body. They are present in all body fluids and they are considered to be the most important antibodies for fighting against bacterial and viral infections. These antibodies help protect the fetus from developing an infection inside the womb.
  • Immediately after birth, the newborn has high levels of the mother's antibodies in the bloodstream. Babies who are breastfed continue to receive antibodies via breast milk. Breast milk contains all five types of antibodies, including immunoglobulin A (IgA), immunoglobulin D (IgD), immunoglobulin E (IgE), IgG, and immunoglobulin M (IgM). This is called passive immunity because the mother is "passing" her antibodies to her child. This helps prevent the baby from developing diseases and infections.
  • During the next several months, the antibodies passed from the mother to the infant steadily decrease. When healthy babies are about two to three months old, the immune system will start producing its own antibodies. During this time, the baby will experience the body's natural low point of antibodies in the bloodstream. This is because the maternal antibodies have decreased, and young children, who are making antibodies for the first time, produce them at a much slower rate than adults.
  • Once healthy babies reach six months of age, their antibodies are produced at a normal rate.

Author information
  • This information has been edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (

  1. American Academy of Allergy Asthma & Immunology. .
  2. American College of Allergy, Asthma & Immunology. .
  3. Byun HJ, Jung WW, Lee JB, et al. An Evaluation of the Neonatal Immune System Using a Listeria Infection Model. Neonatology. 2007 Mar 14;92(2):83-90 [Epub ahead of print.] .
  4. Lopez Alvarez MJ. Proteins in human milk. Breastfeed Rev. 2007 Mar;15(1):5-16. .
  5. Natural Standard: The Authority on Integrative Medicine. .
  6. Paramasivam K, Michie C, Opara E, et al. Human breast milk immunology: a review. Int J Fertil Womens Med. 2006 Sep-Oct;51(5):208-17. .
  7. Schack-Nielsen L, Michaelsen KF. The effects of breastfeeding I: effects on the immune system and the central nervous system. Ugeskr Laeger. 2007 Mar 12;169(11):985-9. .

Integrative therapies
  • Good scientific evidence:
  • Probiotics: Probiotics are beneficial bacteria that are sometimes called friendly germs. They help maintain a healthy intestine and help the body digest foods. They also help keep harmful bacteria and yeasts in the gut under control. Most probiotics come from food sources, especially cultured milk products. Research suggests that probiotics, especially those in milk or food, may be an effective agent for immune system enhancement. However, commercially produced yogurt may not be as effective. More studies are needed, particularly with yogurt, to give recommendations.
  • Probiotics are generally considered safe and well tolerated. Probiotics appear to be safe during pregnancy and breastfeeding. Avoid if allergic or hypersensitive to probiotics. Use cautiously if lactose intolerant.
  • Zinc: Zinc formulations have been used since ancient Egyptian times to enhance wound healing. Zinc appears to be an essential trace element for the immune system, but research on the effect of zinc supplementation on immune function is scant and mostly focuses on patients with specific diseases. Zinc gluconate appears to exert beneficial effects on immune cells, improving CD3 and CD4 counts and increasing CD4/CD8 ratios in children. There are relatively few studies that examine zinc levels and the effects of zinc supplementation on the health of the elderly population. Further research is needed before a recommendation can be made.
  • Zinc is generally considered safe when taken at the recommended dosages. Avoid zinc chloride because studies have not been done on its safety or effectiveness. Zinc is categorized as Pregnancy Category A. If this drug is used during pregnancy, the possibility of fetal harm appears remote. Because studies cannot rule out the possibility of harm, however, zinc acetate should only be used during pregnancy if clearly needed. Zinc appears to be safe in amounts that do not exceed the established tolerable upper intake level.
  • Unclear or conflicting scientific evidence:
  • Beta-carotene: Beta-carotene is a member of the carotenoids, which are very colorful (red, orange, yellow), fat-soluble compounds. They are naturally found in many fruits, grains, oil, and vegetables, including green plants, carrots, sweet potatoes, squash, spinach, apricots, and green peppers. Preliminary research of beta-carotene for immune system enhancement shows mixed results. Further research is needed before a conclusion can be drawn.
  • Avoid if sensitive to beta-carotene, vitamin A or any other ingredients in beta-carotene products.
  • Copper: Copper is a mineral that occurs naturally in many foods, including vegetables, legumes, nuts, grains, fruits, shellfish, avocado, beef, and animal organs, (e.g. liver and kidney). Copper is involved in the development of immune cells and immune function in the body. Severe copper deficiency appears to have adverse effects on immune function, although the exact mechanism is not clear.
  • The recommended dietary allowance (RDA) is 1,000 micrograms for pregnant women. It is unclear if copper supplementation is necessary during pregnancy to maintain adequate levels. Copper is potentially unsafe when used orally in higher doses. The RDA for breastfeeding women is 1,300 micrograms. Copper is potentially unsafe when used orally in higher doses. Copper is present in breast milk as a natural mineral and it is necessary for healthy babies.
  • Massage: The main goal of massage is to help the body heal itself. Touch is fundamental to massage therapy and is used by therapists to locate painful or tense areas, to determine how much pressure to apply, and to establish a therapeutic relationship with clients. Preliminary evidence suggests that massage therapy may preserve immune function. Further research is needed before a firm conclusion can be made.
  • Massage should not be used as a substitute for more proven therapies for medical conditions. Massage should not cause pain to the client.
  • Probiotics: Lactobacillus fermentum (CECT5716) may increase the protective effects of the flu vaccine. More research is needed regarding the use of probiotics as a vaccine adjunct.
  • Probiotics are generally considered safe and well tolerated. Probiotics appear to be safe during pregnancy and breastfeeding. Avoid if allergic or hypersensitive to probiotics. Use cautiously if lactose intolerant.
  • Reflexology: Reflexology involves the application of manual pressure to specific points or areas of the feet called "reflex points" that are believed to correspond to other parts of the body. Some research suggests that self-administered reflexology may be beneficial for immune enhancement. Additional study is needed in this area.
  • Reflexology should not delay diagnosis or treatment with more proven techniques or therapies.
  • Vitamin A: Vitamin A is a fat-soluble vitamin. Vitamin A deficiency may compromise immunity, but there is no clear evidence that additional vitamin A supplementation is beneficial for immune function in patients who are not vitamin A deficient.
  • Pregnant women should not take doses of vitamin A higher than the recommended dietary allowance because Vitamin A excess, as well as deficiency, has been associated with birth defects. Vitamin A is excreted in human breast milk. Benefits or dangers to nursing infants are not clearly established. Avoid if allergic or hypersensitive to vitamin A. Vitamin A toxicity can occur if taken at high dosages. Use cautiously with liver disease or alcoholism. Smokers who consume alcohol and beta-carotene may have an increased risk for lung cancer or heart disease.
  • Vitamin B6: Major sources of vitamin B6 include: cereal grains, legumes (beans), vegetables (like carrots, spinach, peas), potatoes, milk, cheese, eggs, fish, liver, meat, and flour. Vitamin B6 has been shown to be important for immune system function in older individuals. One study found that the amount of vitamin B6 required to reverse immune system impairments in elderly people was more than the current recommended dietary allowance (RDA). Well-designed clinical trials on vitamin B6 supplementation for this indication are needed before a conclusion can be made.
  • Vitamin B6 is likely safe when used orally in doses not exceeding the recommended dietary allowance (RDA). Avoid if sensitive or allergic to any vitamin B6 product ingredients. Some individuals seem to be particularly sensitive to vitamin B6 and may have problems at lower doses. Avoid excessive dosing. Use cautiously if pregnant or breastfeeding.
  • Vitamin D: Vitamin D is found in many foods, including fish, eggs, fortified milk, and cod liver oil. The sun also helps the body produce vitamin D. Preliminary human evidence suggests that vitamin D and its analogues, such as alfacalcidol, may act as immunomodulatory agents. High quality clinical studies are needed to better understand the effects of vitamin D on immunomodulation.
  • Avoid if allergic or hypersensitive to vitamin D or any of its components. Vitamin D is generally well-tolerated in recommended doses; doses higher than recommended may cause toxic effects. Vitamin D is safe in pregnant and breastfeeding women when taken in recommended doses.
  • Vitamin E: Vitamin E exists in eight different forms ("isomers"): alpha, beta, gamma and delta tocopherol; and alpha, beta, gamma, and delta tocotrienol. Alpha-tocopherol is the most active form in humans. Studies of the effects of vitamin E supplementation on immune system function have yielded mixed results. Further research is needed before a clear conclusion can be drawn.
  • Many prenatal vitamins contain small amounts of vitamin E. Natural forms of vitamin E may be preferable to man-made forms. The recommended daily allowance (RDA) of vitamin E for pregnant women of any age is 15 milligrams. The RDA for breastfeeding women of any age is 19 milligrams. Use beyond these levels in pregnant or breastfeeding women is not recommended. Avoid if allergic or hypersensitive to vitamin E. Avoid with Retinitis pigmentosa (loss of peripheral vision). Use cautiously with bleeding disorders.

  • General: During the last few weeks of pregnancy until several days after childbirth, new mothers secrete thick, yellow-white milk from their breasts called colostrum. Although colostrum is low in volume, it contains high amounts of carbohydrates (sugar), proteins, and antibodies. It is also low in fat, making it easier for newborns to digest. Colostrum acts as a laxative, helping babies pass their first stools. About seven to 10 days after delivery, the mother begins to secrete breast milk.
  • Research suggests that babies who are breastfed are less likely to develop infections (especially lung infections, ear infections, and diarrhea) during their first year of life than babies who are fed formulas. This is because the mother's breast milk contains important antibodies, enzymes, fats, and proteins that help boost the baby's immune system. Although baby formulas contain all of the important vitamins and nutrients a growing baby needs, manufacturers have not been able to replicate all of the components in breast milk. Formulas lack antibodies and they are more difficult for newborns to digest.
  • Antibodies: Normally, acid in the stomach is strong enough to break down and destroy immunoglobulin antibodies. However, the baby's stomach acid does not break down the antibodies in the mother's breast milk. This is because the mother's mammary (breast) glands package immunoglobulins with a protective substance. This allows the immunoglobulin to reach the infant's intestine, where it is absorbed into the bloodstream. Once the immunoglobulins enter the bloodstream, they move throughout the body, searching for any foreign substances that may harm the body.
  • Infants who are breastfed primarily receive immunoglobulin A (IgA) via breast milk. IgA antibodies are primarily found in the nose, airway passages, digestive tract, ears, eyes, saliva, tears, and vagina. These antibodies protect body surfaces that are frequently exposed to foreign organisms and substances from outside of the body. Therefore, the mother's IgA helps the infant fend off disease-causing organisms that enter these body surfaces.
  • The other four types of immunoglobulin, including immunoglobulin D (IgD), immunoglobulin E (IgE), immunoglobulin G (IgG), and immunoglobulin M (IgM), are also transmitted to the baby through breast milk. These antibodies also help with immune functioning.
  • IgD antibodies are found in small quantities in the tissues that line the abdominal and chest cavity of the body. Even smaller amounts are present in the blood. The function of IgD antibodies is not well understood. Researchers believe that they play a role in allergic reactions to some substances, such as milk, medications, and poisons.
  • IgE antibodies reside in the lungs, skin, and mucous membranes. They induce allergic reactions against foreign substances, such as pollen, fungus spores, parasites, and animal dander. IgE antibody levels are often high in people who have allergies. When IgE is active, an allergic reaction occurs.
  • IgM antibodies are the largest type of antibody. They are found in the bloodstream and lymph fluid. The IgM antibodies are the first antibodies that are produced in response to an infection. They also stimulate other immune system cells to produce compounds that can destroy foreign invaders.
  • Lysozyme: An enzyme called lysozyme is also present in breast milk. This enzyme enhances the ability of IgA to fight against certain disease-causing organisms.
  • Oligosaccharides: Sugar molecules called oligosaccharides prevent harmful bacteria from multiplying and causing an infection. They bind with bacteria, forming a compound with the bacteria that the baby excretes from the body.
  • Milk lipids (fats): Milk lipids (fats) damage the outer surface of certain types of viruses. When the viruses are damaged, they are unable to replicate and cause an infection in the baby.
  • Proteins: A protein called lactoferrin is present in breast milk. When this protein binds to iron, it prevents disease-causing bacteria from consuming it. Bacteria need iron to survive. Therefore, lactoferrin helps kill the bacteria and infection is prevented.
  • Another protein called mucin is present in breast milk. Mucin attaches to bacteria and viruses that enter the baby's body. When this happens, other cells in the immune system will destroy the disease-causing substance.
  • Two proteins called interferon and fibronectin also help destroy viruses that enter the baby's body.

  • Since babies have underdeveloped immune systems, they are more vulnerable to infections and diseases than adults, even with the passive immunity they gain through their mothers. Thus, several vaccines are given to babies to help protect them against illnesses.
  • Vaccines work by stimulating the body's immune system. Vaccines contain small amounts of inactivated, disease-causing organisms. This allows the immune system to produce antibodies to the foreign invader. Once antibodies are developed, the immune system is able to respond quickly to the infection if the disease-causing organism ever enters the body. After receiving a vaccine, the patient becomes immune to the specific illness.
  • Babies typically receive vaccines for diphtheria, tetanus, hepatitis, pertussis (whooping cough), polio, measles, rubella (German measles), mumps, and a type of flu called Hemophilus B. influenza.
  • Most vaccines are given when the baby reaches two months old because this is when the high level of antibodies passed on by the mother begins to decline. Many vaccines require more than one shot. These additional shots, also called booster shots, ensure that enough antibodies are produced to make the vaccine effective.
  • In general, vaccines are considered safe and effective for babies. Side effects may include a mild fever or skin rash.

Food allergies
  • If babies are exposed to certain types of food at a young age, they may be more likely to develop food allergies. This occurs when the child's immune system overreacts to proteins in certain foods called allergens. Allergy symptoms may range from mild to severe. The most severe reaction, called anaphylaxis can be potentially life threatening. The most dangerous symptoms are chest pain, difficulty breathing, shock, and loss of consciousness, all of which can be fatal.
  • Low-dose exposure to peanut protein or peanut oil products may cause peanut allergies in children, according to one study. The American Academy of Pediatrics recommends that children do not eat peanuts or peanut-containing products until they are three years old, if they have experienced allergies to other foods. Strawberries should also be avoided until the baby is about 10-12 months old.
  • Children whose mothers have food allergies are more likely to inherit the allergy if they are born by cesarean section (surgical delivery of the baby, also called C-section), according to one study. One study of children with allergic mothers who had C-section deliveries found that the babies were seven times more likely to develop food allergies than predisposed children who were born vaginally.

Copyright © 2011 Natural Standard (

The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.

Search Site