May 17, 2010 -- Infants who are exclusively breastfed are less likely to run fevers after their routine immunizations than infants who are partially breastfed or only receive formula, a new study shows.
As many moms can attest, babies can become very fussy and develop fevers after routine vaccinations, resulting in a sleepless night for the entire household and perhaps a few panicked calls to the pediatrician.
But new research conducted at a vaccination center in Naples, Italy, found that exclusively breastfed infants are less likely to develop a fever when compared to infants who are partially breastfed and those who are exclusively formula-fed.
The study is published in the June issue of Pediatrics.
Advantages of Breastfeeding
The American Academy of Pediatrics recommends exclusive breastfeeding for the first six months of an infant's life, and continued breastfeeding for at least the first year. Breastfed babies have lower risks for developing ear infections, respiratory tract infections, and several other infectious diseases.
Breastfeeding has also been linked to a lower risk of sudden infant death syndrome (SIDS), obesity, asthma, diabetes, and some cancers in children. Moms who breastfeed also reap some benefits including quicker post-pregnancy weight loss, lower risk of breast cancer and ovarian cancer, and possibly a reduced risk of hip fractures and the brittle bone disease osteoporosis as they age.
Infants in the new study had received their first or second dose of the combination vaccine to prevent six diseases: diphtheria, tetanus, pertussis (whooping cough), Haemophilus influenzae type B, poliovirus, and hepatitis B co-administered with a vaccine to prevent pneumococcal meningitis. The moms were taught how to take temperatures rectally and told to take their infants' temperature on the night that the shots were given and for the following three days.
Of 460 infants, 25% of infants who were exclusively breastfed developed a fever, as did 31% of infants who were partially breastfed and 53% of those who were exclusively formula-fed. The protective effects of breastfeeding held even after researchers took into account other risk factors for fever such as vaccine dose, maternal smoking, maternal education, and the presence of other children in the household.
"This study suggests that breastfed infants are less likely to have fever after immunization compared with those who are not breastfed," conclude researchers led by Alfredo Pisacane, MD, a pediatrician at the Università Federico II in Naples, Italy.
The study does have some shortcomings, including the fact that moms, rather than doctors, took their infants' temperature.
Why Breastfeeding May Reduce Risk of Fever
Exactly why breastfed infants are less likely to develop a fever after getting shots is unclear, but breast milk may contain certain anti-inflammatory substances that could potentially reduce fever risk. It may also be due to the fact that breastfed infants are less likely to stop eating when they don't feel well because breastfeeding provides a sense of comfort during illness.
"This is another great reason to breastfeed," says Laura Wilwerding, MD, a lactation consultant and a clinical associate professor of pediatrics at the University of Nebraska Medical Center in Omaha. "Getting immunized is traumatic for infants, and anything that we can do to decrease side effects is great."
There are other benefits from breastfeeding when it comes to immunizations, she says.
"Breastfeeding during the actual shot process decreases discomfort," she says. "It may be that the sheer comfort of being with mom in such a natural way takes the infant's mind off of the pain of the shots."
What's more, "immunizations have been shown to work better in babies who are breastfed," she says.
The new findings also make intuitive sense to Barbara Holmes, a lactation specialist New York University Langone Medical Center. "Babies want to nurse more frequently, and because they are nursing more frequently, they are getting more food [than formula-fed infants], so whatever need they have to repair their body and bring down the fever is being met," she says.
"It could be that there is some anti-inflammatory protective benefit in breast milk," says Natali Aziz, MD, a maternal-fetal medicine specialist at Lucile Packard Children's Hospital in Palo Alto, Calif. She tells WebMD that she routinely encourages new moms to breastfeed. "There is a significant amount of data and research that maternal antibodies are transferred during breastfeeding and can be protective against viral infections."