Breastfeeding and new vaccines are bringing down the risk of ear infections in infants, a U.S. study suggests.

About 46 percent of infants get at least one ear infection by their first birthday, and this remains the leading reason for infant sick visits and antibiotic prescriptions. But that's down from at least 60 percent as recently as the 1990s, researchers report in the journal Pediatrics.

Babies in the study were much less likely to get ear infections if they were breastfed and if they received vaccines to protect against flu and against Streptococcus pneumoniae bacteria, which can cause infections of the ears, sinuses, lungs, and blood.

"Parents should make sure their children receive bacterial and flu vaccines as recommended, breastfeed them as recommended, avoid cigarette smoke exposure and exposure to someone with common cold," said lead study author Dr. Tasnee Chonmaitree of the University of Texas Medical Branch in Galveston.

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These measures will help lower the odds of ear infections, even if they can't always be avoided as a complication of the common cold.

"The common cold often leads to bacterial and viral ear infections, therefore ear infections are still common, although the incidence is down," Chonmaitree added by email.

Chonmaitree and colleagues followed 367 healthy babies during their first year of life, monitoring them for at least six months or until they developed an ear infection.

During the study period, 305 infants had respiratory infections that can lead to ear infections, and 180 ear infections were documented in a total of 143 babies.

Breastfeeding significantly reduced the risk of both upper respiratory infections and ear infections. Exclusive breastfeeding for at least three months, longer duration of breastfeeding, and delayed start of exclusive formula feeding were all associated with lower risk of ear infections.

Pediatricians recommend that mothers exclusively breastfeed infants until at least six months of age because it can reduce babies' risk of ear and respiratory infections, sudden infant death syndrome, allergies, childhood obesity and diabetes.

Babies can receive the pneumococcal vaccine starting at two months of age. They need a series of booster shots to increase the effectiveness.

Children born after 2010 who received a newer version of the pneumococcal vaccine that protects against more strains appeared to have fewer ear infections, but the difference was too small to rule out the possibility that it was due to chance. The study may not have included enough ear infections to prove the benefit of this vaccine, but it is likely to have influenced the decline ear infections, the authors conclude.

Less exposure to cigarette smoke was also associated with fewer ear infections, though these results too, weren't statistically meaningful.

"Interventions that reduce the level of bad germs in a child's nose and throat will help reduce ear infections," said Dr. Richard Rosenfeld, chairman of ear, nose and throat medicine at SUNY Downstate Medical Center in New York.

"Breastfeeding helps boost a child's immune system by providing antibodies and immune globulins that fight germs," Rosenfeld added by email. "Decreased smoke exposure reduces irritation of the mucus membrane lining of the nose and Eustachian tube, which makes it harder for germs to grow and reach the middle ear."

"Last, new vaccines make children more resistant to the common bacteria and viruses that trigger ear infections."