Breast-feeding longer may increase baby's intelligence

Breast-fed babies may be getting a boost to their intelligence.

New research shows that longer breast-feeding times are associated with better language skills at age 3 and better verbal and nonverbal intelligence at 7 years old.

"It adds to the literature in support of the idea that breast-feeding does positively impact a child's intelligence," lead author Dr. Mandy Belfort, a pediatrician at Boston Children's Hospital, said to USA Today. "I don't think there's any one study that's going to be a complete slam dunk, but it's definitely evidence in support of that idea."

The Office on Women's Health of the U.S. Department of Health and Human Services says that most leading health organizations suggest that babies are breast-fed for at least 12 months, and are exclusively fed breast-milk for the first six months of their lives.

Breast-feeding offers protection to babies and also provides added benefits for mothers. The milk contains antibodies that protect the infants from illness. Breast-feeding has been associate with lower rates of ear infections, stomach viruses, respiratory infections, atopic dermatis, asthma, obesity, Type 1 and Type 2 diabetes, childhood leukemia, a gastrointestinal disease known as necrotizing enterocolitis and sudden infant death syndrome (SIDS).

For the study, researchers looked at 1,312 mothers and children involved in the Project Viva study. The mothers were enrolled between April 2009 to July 2012, and the children were followed up with until they were 7 years old. The researchers controlled for other variables that could impact intelligence, including the mother's intelligence and the child's home environment.

The researchers specifically looked at how long children were breast-fed and how much fish the mother ate during breast-feeding, since omega-3 fatty acids have been previously shown to aid in brain development. Cognitive tests were used to judge the child's intelligence levels.

The researchers found that children who were breast-fed scored significantly higher on a picture-vocabulary test at 3 years old. For each additional month of breastfeeding, children scored 0.21 points higher.

Kids who were breast-fed longer also scored better on an intelligence test given to them at 7 years old. Each additional month of breastfeeding was associated with an 0.35 points higher score on the verbal section, and an 0.29 points higher score on the non-verbal score.

They also found that mothers who ate at least two servings of fish per week had children with better visual motor abilities at the age of 3. However, these improvements were not statistically significant.

"We found a little hint in that direction, but nothing definitive," Belfort said. "And we certainly didn't find any evidence that eating fish while breast-feeding was harmful, which is important because there are some concerns about mercury in fish being toxic to the developing brain."

In an accompanying editorial, Dr. Dimitri A. Christakis, a professor of pediatrics at the Seattle Children's Hospital Research Institute, wrote that the modest improvements in test scores correlated to about a four point IQ increase or one-third of a standard deviation.

"However, the problem currently is not so much that most women do not initiate breastfeeding, it is that they do not sustain it," he wrote. "In the United States about 70 percent of women overall initiate breastfeeding, although only 50 percent of African American women do. However, by six months, only 35 percent and 20 percent, respectively, are still breastfeeding."

Christakis encouraged more programs and opportunities to help encourage mothers to breast-feed and called for a de-stigmatization of breast-feeding in public.

"Clever social media campaigns and high-quality public service announcements might help with that. As with lead, some of these actions may require legislative action either at the federal or state level. Let's allow our children's cognitive function be the force that tilts the scale, and let's get on with it," Christakis said.

Breast-feeding has also been linked to an improvement in social status, according to a study published in June in BMJ's Archives of Disease in Childhood.

The mother can also experience a better bond with their child and save money on formula if she breast-feeds. It can also lower her risk of type 2 diabetes, certain cancers and postpartum depression. One recent Obstetrics & Gynecology study showed that if people stuck with the recommended length of breast-feeding time, there would be 5,000 fewer cases of breast cancer, 54,000 fewer cases of hypertension and almost 14,000 less heart attacks in women each year.

However, the Centers for Disease Control and Prevention found that 40 percent of parents started giving their children solid food before they were 4-months-old despite the six-month recommendation. Another study showed that while breast-feeding rates went up for all race and ethnic groups from 2000 to 2008 in the U.S., it was still shy of optimal levels. Only 45 percent of mothers were still exclusively breast-feeding at 6 months of age in 2008.

Dr. Ruth Lawrence, a breastfeeding researcher from the University of Rochester Medical Center in New York, said she found the new research sound. She was not involved in the study.

"The difficulties with any study are, what were the intellectual capacities of the parents, and did this make a difference?" Lawrence commented to Reuters. "They showed very clearly that when you controlled for all those parameters, breastfeeding still was associated with higher intellectual development."

The study was published in JAMA Pediatrics on July 30.

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