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comment analysis today Wednesday 4 July 201218 today Wednesday 4 July 2012comment analysis19

Why breast-feeding wont make kids smarter

Advocates of so-called attach-ment parenting take an all-en-compassing approach: Assidu-

ous attention to a childs every need,including prolonged breast-feeding.But those who claim that these prac-tices benefit childrens intelligence

miss an important point.

PASSING SMART GENES

In the United States, a mother whose IQis 15 points higher than her neighboursis more than twice as likely to breast-feed. Women who breast-feed are more

educated and less likely to smoke.

attaCHMent PaRentInG

Sam Wang,an AssociateProfessor ofMolecular Biologyand Neuroscienceat PrincetonUniversity, andSandra Aamodt,a former Editor-in-Chief of NatureNeuroscience,are authors ofWelcome to Your

Childs Brain.

Intelligent parents pass along theirgenes and also create a more stimulat-ing environment, two advantages forthe babys development.

In short, smart mothers havesmart babies.

In one analysis of multiple stud-ies, combining data from more than5,000 children, the IQ dierences as-sociated with breast-feeding wereeliminated when the mothers char-acteristics were taken into account.Among 332 pairs of siblings in whichone was breast-fed and the other bot-tle-fed, researchers also found no dif-ference in IQ.

So, mothers who are unable tobreast-feed need not worry that theyare harming their babys intellectualdevelopment. Indeed, adopted chil-

dren, many of whom are not breast-fed, have higher IQs, on average, thantheir siblings who remain in the birthfamily, presumably because theiradoptive families provide an environ-ment better suited to cognitive devel-opment.

A key factor in development is thefamilys socio-economic status acombined measure of income, occu-pation and education. The possible ef-fect of environment can be measuredby comparing dierences w ithin thesame household in outcomes betweenidentical twins, who share all theirDNA, with those between fraternaltwins, who share half their DNA.

ENVIRONMENTAL INFLUENCE

In middle-class households, identicaltwins have more similar outcomesthan fraternal twins have, suggestingthat environmental inuences have asmaller impact than genetics on thegrowth of childrens intelligence. It

seems that most middle-class envi-ronments are good enough to allowmost children to approach their fullgenetic potential.

For children growing up in house-holds of low socio-economic status,on the other hand, good parenting iscrucial.

In one recent study, parents IQinuenced the childs IQ at two yearsof age but not if the household waslow-status. In seven-year-olds, only10 per cent of IQ variability in low-sta-tus children was attributable to genes.In other words, a poor environmentcan wipe out genetic advantages.

Low social status often means eco-nomic insecurity, unsafe neighbour-hoods and chaotic households.

And it means increase d secretionof stress hormones. At age 10, low-sta-tus children have twice as much stresshormone in their blood as high-statuschildren do.

Chronic stress reduces the volumeof the hippocampus, a brain region in-

volved in learning, and leads to memo-ry problems. It also interferes with de-velopment of the frontal cortex, whichis important for planning and organ-ising behaviour and for self-control.

SOCIAL PRESSURES ON MUMS

The inuence of social environmentcan even outweigh physical hazards:

High-status children recover fromlead poisoning better than low-statuschildren do.

For these reasons, efforts to en-courage young mothers to breast-feed should take into account theireconomic circumstances. Workingmothers, already strapped by the ex-

penses of new parenthood, cannotnecessarily afford to shell out hun-dreds of dollars for a breast pump andaccessories.

The next barrier comes at work,where pu mping requir es a privat eroom with an electrical outlet. Onewoman we k now, a p hlebot omist ,could not nd a regular place or timeto pump until her baby was morethan three months old, too late for themother to begin lactating.

In contrast, a physician who gavebirth around the same time regularlycaught up on work at her computerwhile using a n electric breast pumpin her private oce.

Of course, breast-feeding is ahealthy thing to do. It enhances thebabys immune system, and builds abond with mum. But social pressu reon mothers may itself be harmful tochildren. Stress hormones can bepassed from mother to baby duringpregnancy and nursing.

NO ONE TRUE WAY

Even in families of modest means,effective strategies are availableto help a babys brain grow. Babieslearn best from communicating withother people, especially with thosewho respond t o them promptly andappropriately.

Support programmes that trainmothers to be more responsive totheir babies lead to improved cogni-tive development.

An anal ysis of mu ltiple studie sinvolving 900 mother-infant pairsshowed that short-term behaviouraltraining for mothers to enhance sen-sitivity also made children more like-ly to form a secure attachment to themother, a major goal of attachmentparenting. Such interventions are es-pecially eective for mothers of fussyinfants.

There is no One True Way to be amother, as humans have been raisingchildren successfully under a varie-

ty of circumstances for thousands ofyears. Putting pressure on women toadhere to a particular set of practicesthat may not t their lives is likely tobe counter-productive.

Societal support, on the otherhand, including support for breast-feeding where possible, can help allparents to help their children growup well. BLOOMBERG

A childs biggest advantage arisesfrom having the family resources thatmake such care-giving possible in therst place. In this sense, attachmentparenting is a trend among familieswhose children need it least the af-uent. Fortunately, there is a way forparents of lesser means to get similarbenets.

Attachment parenting has not yetbeen subjected to rigorous scienticstudy. It is not known, for example,

if it makes kids more independent or

secure. But one claim has been thor-oughly investigated: That breast-feeding increases a childs IQ. Evenmany mothers who return to workbelieve their breast milk to be essen-tial to their babies future intellect.Research shows that this is a myth.

Although it is t rue that childrenwho were brea st-fed as babies havehigher intelligence than bottle-fedchildren, the reason for the correla-tion is in the mothers brain, not her

breast.

Of course, breast-feeding is a healthything to do. It enhances

the babys immune system,and builds a bond with mum.

There is noOne True Way tobe a mother, as humans

have been raising childrensuccessfully under a varietyof circumstances for thousandsof years. Putting pressureon women to adhere to aparticular set of practices thatmay not t their lives is likelyto be counter-productive.

SAM WANG ANDSANDRA AAMODT

According to the authors, the reason for the correlation between breast-feeding and intelligence is in themothers brain, not her breast. POTOREUTERS