Immunity Boosts for Your Baby: 3 to 6 MonthsThe family member who can lower your baby’s risk of allergies.

Germs—such as viruses, bacteria, and parasites—are everywhere. But try not to worry too much: They can actually be good for your baby to a certain extent, since exposure to germs helps build her developing immune system. Each day, she’s naturally exposed to hundreds, possibly thousands, of new antigens—including dust, pollen, bacteria, and viruses—which trigger an automatic immune response. Vaccines, of course, expose her to still other antigens that will help her fend off dangerous diseases. The goal is to help strengthen and educate her immune system.

Nutrition

Continue to support your baby’s immune system. Breast milk provides your baby with a range of protective antibodies. If you’re formula feeding, look for a brand that has prebiotics, which feed the good bacteria that occur naturally in the digestive tract, where 70 percent of an infant’s immune system is located. Scientists believe prebiotics may support the developing immune system.

Ask your pediatrician for advice about starting on solids. Babies aren’t developmentally ready for solids until 4 to 6 months, with most experts considering 6 months the ideal time to begin gradually introducing them. Many pediatricians recommend introducing strained meats first, to help provide iron and other nutrients.  However, most parents are used to introducing single-grain cereals and strained fruits and vegetables. After introducing a new food, it’s best to wait a few days before introducing another one in order to gauge whether there’s an intolerance.  In the past, parents were advised to hold off on peanuts, eggs, and other common allergens until after the first birthday, but there is now clinical evidence that delaying impacts the risk of allergy. If there’s a family history of allergies, be sure to follow your pediatrician’s instructions. It’s always best to consult with your pediatrician for a recommendation individualized to your child.

Health Care

Make sure your baby gets each dose in a vaccine series. Most routine childhood vaccines require multiple doses at set intervals. Vaccines work by mimicking a natural infection, teaching the body’s immune system how to fight off a given invader. Your doctor will review your baby’s record at well-baby visits and recommend changes to the schedule if your baby is ill or has missed any shots in a series.

Germs

Settle for a clean enough, not necessarily spotless, home. Many experts believe that the tendency in recent years toward over-sanitizing has contributed to the boom in childhood allergies. According to a well-regarded theory, known as the hygiene hypothesis, excessive cleanliness disrupts the natural development of the immune system by eradicating germs that in the past have allowed humans to develop protective antibodies.

Consider adding to your family even more—with a pet. Although it’s unclear exactly why, many studies have shown that kids who are raised with cats and dogs have fewer allergies and cases of asthma. One study of nearly 600 children found that those who had a furry pet were less likely to have allergies to the animal at 18 years of age—and that the effect was especially strong when pet ownership began in the first year of life. (The benefit was greatest among firstborns.)

Give a dropped pacifier a quick rinse. Some parents clean off a dropped pacifier in their own mouth before giving it to back to their baby. Studies show this isn’t a bad idea: In one, babies up to 6 months old whose parents used this approach had reduced risk of developing eczema at 18 and 36 months.

Don’t worry excessively about day care making your baby sick. Despite your best efforts, at some point your baby will get sick. All babies do; it’s part of growing up and developing a healthy immune system. While it’s true that babies who attend day care pick up more infections than those who stay at home, research shows that exposure to a variety of germs may in fact improve overall immune system function.