(Reuters Health) - Babies who are breastfed for at least two months may have a lower risk of sudden infant death syndrome (SIDS) during sleep than babies who aren’t nursed as long, a research review suggests.
Pediatricians recommend that mothers exclusively breastfeed infants until they’re at least six months of age because it can reduce babies’ risk of SIDS as well as ear and respiratory infections, allergies, childhood obesity and diabetes. But research to date hasn’t offered a clear picture of exactly how long women need to nurse their infants to protect against SIDS, said John Thompson, lead author of the current study and a pediatrics researcher at the University of Auckland.
“The peak age of SIDS is two to four months, so breastfeeding may need to continue into this apparently more vulnerable period to incur the protective effect,” Thompson said by email.
SIDS has become much less common in recent decades as doctors have urged parents to put infants to sleep on their backs without pillows or other soft bedding and toys that could pose a suffocation risk. But it still remains a leading cause of infant mortality.
The study wasn’t a controlled experiment designed to prove whether or how breastfeeding directly prevents SIDS. However, it’s possible that breast milk helps boost babies’ immune systems and lower the risk of infections that can lead to SIDS, doctors say.
For the study, researchers examined data from eight previously published studies with a total of 2,267 SIDS cases and 6,837 babies who didn’t die in their sleep.
Compared to babies who were not breastfed at all, SIDS was 40 percent less likely in infants who were breastfed at least some of the time for two to four months, researchers report in Pediatrics.
Any breastfeeding for four to six months was associated with a 60 percent lower risk of SIDS, and nursing babies at least some of the time for six months or longer was linked to 64 percent lower odds of SIDS.
Exclusive breastfeeding for less than two months didn’t appear to protect against SIDS. But exclusive breastfeeding for two to four months was associated with 39 percent lower odds of SIDS, and four to six months was linked to 54 percent lower odds.
It’s not clear why breastfeeding didn’t appear to have a protective effect when the duration was less than two months, said Dr. Jeffrey Colvin, a pediatrics researcher at Children’s Mercy Kansas City in Missouri who wasn’t involved in the study.
“We knew that breastfeeding was associated with decreased risk of SIDS and that exclusive breast feeding seemed to impart even greater protection,” Colvin said by email. “I now know the absolute minimum duration of breastfeeding I must reach with every newborn.”
One limitation of the current study, however, is that it’s unclear why exclusive breastfeeding didn’t appear more protective than breastfeeding just some of the time and supplementing with baby formula, the authors note. The smaller studies in the analysis didn’t have information on families’ social and economic status, and this might influence both which babies are exclusively breastfed and which infants get SIDS, the researchers point out.
Parent involvement might also influence breastfeeding and SIDS risk, said Dr. Ian Paul, a researcher at Penn State College of Medicine in Hershey who wasn’t involved in the study.
“I believe parent behaviors are paramount in preventing SIDS,” Paul said by email. “Breastfed infants are likely to have more sustained and frequent interactions with their parents during the night at the key ages when SIDS is most likely to occur.”
There are many reasons to breastfeed babies exclusively for six months and then continue nursing them until age one, said Dr. Lori Feldman-Winter, a pediatrics researcher at Cooper Medical School of Rowan University in Camden, New Jersey, who wasn’t involved in the study.
“SIDS protection is simply one outcome,” Feldman-Winter said by email. “Exclusivity is important for infection protection, obesity prevention, and to decrease diseases linked to autoimmunity, such as Crohn’s. Duration is also important for appropriate growth, continued protection from infections such as gastroenteritis.”
SOURCE: bit.ly/2lqilKF Pediatrics, online October 30, 2017.
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