Babies and children under 3 years of age are more prone to ear infections, also known as the disorder otitis media, than older children or adults. In fact, three out of four babies will develop an ear infection before they reach 3 years old. The causes of ear infections in babies is a combination of infectious agents, an immature immune system and the anatomy of a baby's ear. Other environmental factors may contribute to a baby contracting an ear infection.
Bacterial and Viral Infections
Many different types of bacteria and viruses can lead to an ear infection in babies. Pneumococcal bacteria, colds and seasonal flu are all common culprits, although any infection that affects the sinuses can travel into the middle ear. These infections typically begin as respiratory infections, which then travel into the eustachian tube between the throat and ears. The infection becomes trapped in the eustachian tube and middle ear when the tube becomes inflamed and swollen.
Baby Ear Anatomy
Certain aspects of a baby's ear anatomy contribute to the frequency of infection seen in infants. One such aspect is the size and shape of the eustachian tube. In babies, this tube is narrow, horizontal and about 1/3 of adult size, measuring only about 1/2 inch, according to Baby Center. This makes babies highly prone to blockage. The adenoids, glands that hold immune cells at the top of the eustachian tubes in the throat, are also more prone to swelling and infection in infants than in older children or adults. Swelling of the adenoids can lead to a blockage of the eustachian tube and an infection of the adenoids can spread to the eustachian tube and middle ear.
Immature Immune System
A child's immune system is not well-developed for the first few years of life. This makes infants less able to fight off illnesses that could lead to ear infections. Children who are exposed to more childhood illnesses, such as those in a day care setting, often develop more ear infections because their bodies cannot fight off the diseases they become exposed to. Vaccinations can help boost a baby's ability to fight off specific diseases and prevent ear infections, according to the March of Dimes.
Environmental Factors
Tobacco smoke, air pollution and allergens in the environment can all contribute to the development of ear infections. Formula-fed babies, especially those who are fed with a bottle when lying down or left to fall asleep with a bottle, are up to 70 percent more likely to get ear infections than breast-fed babies, according to Baby Center.
