孕期多吃鱼对胎儿大脑发育有益

Three-year-olds whose mothers ate more fish while pregnant with them score better on several tests of cognitive function than their peers whose mothers avoided seafood， a new study shows.However，. 手

Three-year-oldswhosemothersatemorefishwhilepregnantwiththemscorebetteronseveraltestsofcognitivefunctionthantheirpeerswhosemothersavoidedseafood，anewstudyshows.

However，theresearchersalsofoundthattheamountofmercuryinawomansbodyrosewiththeamountoffishshehadconsumed--andthatchildrenexposedtomoremercuryperformedworseonthesetests.Basedonthefindings，theysay，itspossiblefishcouldhaveevengreaterbrainbenefitsforbabiesifmothers-to-beconsumedseafoodwithlowermercurylevels.

"Recommendationsforfishconsumptionduringpregnancyshouldtakeintoaccountthenutritionalbenefitsoffishaswellasthepotentialharmsfrommercuryexposure，"Dr.EmilyOkenofHarvardMedicalSchoolinBostonandhercolleagueswriteintheMay15issueoftheAmericanJournalofEpidemiology.

Advisoriesonmercurycontaminationofcertaintypesoflarge，long-livedfish--includingtunaandswordfish--haveraisedconcernsaboutseafoodconsumptionduringpregnancy，Okenandherteamnote.Ontheotherhand，fisharealsothechiefdietarysourceofomega-3fattyacids，substanceskeytoearlybraindevelopment，theyadd.

Tobetterunderstandtherisksandbenefitsoffishconsumption，Okenandherteamsurveyed341mothersabouttheirintakeoffishduringthesecondtrimesterofpregnancy，andthenhadtheirchildrencompleteabatteryoftestsofcognitivefunctionat3yearsofage.

Onaverage，womenreportedeating1.5servingsoffisheachweekwhiletheywerepregnant.Theamountofmercurythewomenhadintheirredbloodcellswasdirectlyrelatedtotheamountoffishtheyate.Childrenstestscoresrosewiththeamountoffishtheirmothershadconsumed，butthosewhosemothershadmoremercuryintheirbodiesperformedlesswellonthetests.

Accountingfortheeffectsofmercuryexposurestrengthenedtheeffectoffishintake，andviceversa，theresearchersfound.Benefitswerestrongestforchildrenwhosemothersatemorethantwoservingsaweek.

"Ourfindingthatthebenefitoffishintakeisstrengthenedwithadjustmentformercurylevelssuggeststhatifmercurycontaminationwerenotpresent，thecognitivebenefitsoffishwouldbegreater，"Okenandherteamexplain."Maternalconsumptionoffishlowerinmercuryandreducedenvironmentalmercurycontaminationwouldallowforstrongerbenefitsoffishintake."

SOURCE:AmericanJournalofEpidemiology，May15，2008.