Babies who are breast-fed may be more likely to be successful in life, a provocative study published Tuesday suggests.
The study followed more than 3,000 babies into adulthood in Brazil. The researchers found those who were breast-fed scored slightly higher in intelligence tests in their 30s, stayed in school longer and earned more money than those who were given formula.
"Breast-feeding not only has short-term benefits, but also breast-feeding has long-term benefits," says Bernardo Lessa Horta of the Federal University of Pelotas in Brazil, who led the study being published in The Lancet Global Health.
Doctors have long known that breast-feeding can be good for a baby's health. This is especially true in poor countries, where water can be contaminated with pathogens or pollutants. For instance, a baby given formula in developing countries is 14 times more likely to die in the first six months than one who's breast-fed, UNICEF found.
Here in the U.S., some research has suggested that breast-feeding may boost a baby's IQ by a few points. But a recent study with siblings found little advantage to breast-feeding.
Horta says these previous studies didn't follow children into adulthood to see if breast-feeding had long-term effects. So Horta analyzed data collected from 3,493 volunteers he and his colleagues have been following since birth. They are now in their 30s.
First, the researchers gave the subjects IQ tests. Those who were breast-fed for 12 months or more had IQ test scores that were 3.76 points higher than those who were breast-fed for less than one month, the team found.
When Horta and his colleagues looked at how much education the subjects had gotten and how much money they were making, they also found a clear difference: Those who were breast-fed the longest stayed in school for about an extra year and had monthly salaries that were about a third higher.
Pediatrician Valerie Flaherman of the University of California in San Francisco warns not to read too much into the findings.
"There's the potential for people to think if you don't breast-feed, your baby will be stupid or mentally impaired or something like that," Flaherman says.
But that's not true at all. Many other factors influence intelligence and a person's chances of being successful, she says.
Many women either can't breast-feed for physical reasons or because they have to go back to work, Flaherman notes. "I do worry that sometimes when mothers hear about projects like this, they feel guilty when they were not able to breast-feed their babies," she says.
"And what I hear from some of my mothers is that if they are giving their babies a bottle in Starbucks or on the bus, they feel like people are giving them dirty looks, or saying they should be breast-feeding," Flaherman adds.
While breast-feeding can be beneficial, she says, it will not necessarily have a relationship with intelligence for any individual child.
But Ruth Lawrence, a professor of pediatrics, obstetrics and gynecology at the University of Rochester, thinks the current study in Brazil is important.
"It proves a permanency of the effects [of breast-feeding] on a child's potential," she says. "I think it's a remarkable study."
RENEE MONTAGNE, HOST:
Babies who are breast-fed tend to be more successful in life. That's the provocative suggestion of a new study being published this week in The Lancet Global Health. The study took place in Brazil, where researchers say breast-feeding rates didn't vary much between women of different economic classes. NPR's health correspondent Rob Stein has the story.
ROB STEIN, BYLINE: Doctors have long known that breast-feeding is good for a baby's health. But Bernardo Horta of the Federal University of Pelotas in Brazil says there's a lot of debate about just how much of a difference breast-feeding makes in a child's life. So Horta and his colleagues took a look at more than 3,000 babies they've been following since they were born. They're now in their 30s. First, they gave them IQ tests.
BERNARDO HORTA: The subjects who were breast-fed for 12 months or more had a higher IQ than those who were breast-fed for less than one month. The difference in IQ was 3.76 points.
STEIN: That may not sound like a lot, but Horta and his colleagues didn't stop there. They also looked at how much education they'd gotten and how much money they were making.
HORTA: We also observed that they had a higher education, as well as a higher monthly income.
STEIN: They earned about a third more than those who got little or no breast-feeding as babies.
HORTA: Breast-feeding is - not only has short-term benefits, but also breast-feeding has long-term benefits, improving the performance and intelligence in adulthood, as well as the income - OK? - the economic productivity.
STEIN: Other researchers praise the study.
RUTH LAWRENCE: I think it's a remarkable study, actually.
STEIN: Ruth Lawrence is a professor of pediatrics, obstetrics and gynecology at the University of Rochester.
LAWRENCE: This proves the permanency of these effects, which are very important, I think, to establish the critical impact of breast-feeding on a child's potential. And it gets into, you know, what are you going to do for the rest of your life, and how much money are you going to make doing it?
STEIN: But other researchers are more cautious. Valerie Flaherman of the University of California in San Francisco says lots of factors influence intelligence and success in life.
VALERIE FLAHERMAN: There's the potential for people to think if you don't breast-feed, your baby will be stupid or mentally impaired or something like that. While it's a potential benefit, it's one factor among many that mothers should consider in their decision.
STEIN: Many women can't breast-feed for physical reasons or because they have to go back to work. And Flaherman worries that women are already being stigmatized if they use formula.
FLAHERMAN: I do worry that sometimes when mothers hear about projects like this, they feel guilty when they were not able to breast-feed their babies. And what I hear from some of my mothers is that, you know, if they are giving their baby a bottle in Starbucks or on the bus or something, they feel like people are giving them dirty looks or saying they should be breast-feeding. So I think that can be a problem for mothers and babies.
STEIN: Horta and Lawrence agree that babies raised on formula can turn out to be just fine, but they say everything should be done to help women breast-feed if they can. Rob Stein, NPR News. Transcript provided by NPR, Copyright NPR.