Gender Differences of Final Height Contributed
by Parents’ Height Among Healthy Individuals
Pen-Hua Su, Shu-Li Wang , Jia-Yuh Chen *
Key Words:corrected midparental; height; final parental height; gender difference; growth evaluation; target height
Background: Estimation of children’s final height is of great interest for pediatric endocrinologists in diagnosing and evaluating the treatment of short stature. The current study was performed to characterize the feature of offsprings’ final heights by their parents’ heights by gender in Taiwan.
Methods: Healthy participants aged 25e35 years who underwent health examinations were recruited for body height measurements with standard processes regulated by a protocol and were enquired about their parental peak adult heights in 2003e2004. Differential contributions from each parent to the tallest/shortest child’s height in the family were then assessed with simple linear regressions with scatter plots by gender. Meanwhile, statistical comparisons with the corrected midparental height method and final height for parental height model were performed.
Results: A total of 1113 male and 1036 female participants were enrolled. The fathers’ height contributed the most to the tallest son’s height in the family (adjusted R2Z0.20), and mother’s height contributed the most to the shortest daughter’s height in the
family (adjusted R2Z0.18). Specifically, the final height for parental height line worked better for the contribution of midparental height to the tallest son’s height in prediction.
Conclusions: For clinical practice, our results provided a reasonable estimation of final heights among local Taiwanese population and are also applicable for the
evaluation of growth hormone replacement therapies for patients with short stature of non-growth-hormone defect.
1. Introduction
The final body height for adults is a polygenic trait influenced by numerous determinants, including nutrition; tempo of maturation; and genetic and
environmental factors during fetal life, childhood, and adolescence.1e5 Estimation of a child’s final height is of major significance for pediatric endocrinologists in
diagnosing, evaluating the need for therapeutic intervention, and responding to parents’ counseling.6 Stature of children is noticeably influenced by parental height,3,7,8 and meanwhile, the genetic basis of adult height is fairly perceptible in monozygotic twins who grow up apart.3 Genetic potential height or target height is usually determined as a function of parental height.9e12 Corrected midparental height (CMH) method computes the target height by adding or subtracting 6.5 cm to the mean of the parental heights for boys or girls, respectively,9 which has been commonly used by clinicians in the evaluation of growth-promoting therapies on growth hormone (GH)-deficient13 and non-GH-deficient children with short
stature.14e16 However, midparental height might contribute more during earlier stage in an offspring’s life11 and be limited for assessing short children of parents with extreme height.17 Another approach proposed for estimating target height is known as the final height for parental height (FPH) model.10 The FPH model is preferred for target-height estimation among Swedish children, as the CMH method leads to an underestimating bias of about 6 cm for children with short parents.9 One study compared the validities of CMH and FPH methods for estimating target height in Hong Kong Chinese
children.12 On average, this population was shorter than the Swedes by more than 10 cm. Their secular increase in height over the two generations, however, was 4.2e4.8 cm,
which was much greater than that of the Swedes (0.7e1.0 cm). Taiwanese people have experienced a dramatic socioeconomic transformation in the past 5 decades. Thus, the association between parental height and children’s final height may also have
changed.18 The aim of this study was to suggest a new approach to characterize the feature of tallest/shortest boys’ and girls’ final heights, predicted by the height of their parents in a large sample of healthy Taiwanese who were born in the 1970s. Our results may provide further insight into the basis for enhancing accuracy in the estimation of target height by
each gender and further evidence of differential contribution from male/female parents for the achieved final height for boys and girls.
2.Methods
ted1229familieswithhealthyoffspringsagedbetween25yearsand35yearsforhealthexami nationsatamedicalcenterincetralTaiwan.Age,sex,height,andexaminedmedicalandfamil yhistorieswererecordedatclinicalvisits.Familieswitheitherparentsoroffspringshavinghy popituitarism,hypothy-roidism,chromosomalabnormality,historyofpoliomy- elitis,antenatalbetamethasoneexposure,ormalnutritionwereexcludedfromouranalyses. 2.2.Datacollection Dataaboutoffsprings’bodyheightswerecollectedbyaquestionnaireafterthestandardmeas urementsoftheirparents’heightswitacalibratedHarpendenstadiometer(theheightbaronast andardhospitalscale)byawell-trainedstaffinhealthexaminations.Parentswererequestedto reporttheiradultpeakheight,numberofoffspringsineachgender,andheightoftheirtallest/sh ortestsonsanddaughters.Thus,eachfamilyprovidedjustonesetofheightinformationtoavoi dtheviolationofindependentobservationassumptioninstatistics.Self- reportedpeakadultheightforparentswasobtained,becausemostoftheseindividualswereint heir50sand60s.Theyhadexperiencedaging-relateddecreasesinheight. Midparentalheightwasdefinedastheaverageoffather’sandmother’sreportedheights.Thes tudywasapprovedbythehospitalethicscommittee,andinformedconsentwasobtainedfrom allparticipants.192.3.StatisticalanalysesTwoanalyticalschemesofattemptsweretakenfort hisstudy.Wetriedtodistinguishthedifferentialcontributionsfromeachparenttothetallest/sh ortestchild’sheightinthefamilybygender.Iftherewasonlyonesonordaughterinafamily,the onlysonordaughterwastakenastheshortestandalsothetallestoneinthefamilyforanalyses. Simplelinearregressionswereusedfortheestimationoftargetheightsoftheoffspringsbypar entalheights.Theexplainablevariationofindependentvariables,parentalheights,withthed ependentvariables,children’sfinalheights,wasexpressedbyadjustedR2,theR2adjustedfor thenumberofparametersinvolvedinthemodel.Scatterplotswithlinearregressionlineswere usedtodepictthedistributionofchildren’sfinalheightsoverparentalheights.Bvalues(slopes ),intercepts,andtheir95% confidenceintervalswereestimatedfortheeffectofparentalheightonchildren’sfinalheight. Meanwhile,forthepurposeofdetectingthedifferencesbetweenmodelsofparentalheightspr edictingtallest/shortestchildreninthefamily,statisticaltestsforcomparinginterceptsandslo pesbetweenregressionswereperformed.Then,thecomparisonsofthescenariosoftallest/sh ortestson/daughterpredictedbymidparentalheightwiththeCMHmethod20andtheFPHmo del10wereperformed.CMHmethodpredictsthetargetheightbyadding6.5cmtothemidpare ntalheightinboysorsubtracting6.5cmfromthemidparentalheightingirls.20TheFPHmodel forestimatingtargetheight(Y)asasimplelinearfunctionofmidparentalheight(X)incentime ters(boys:YZ45.99t0.78X;girls:YZ37.85t0.75X)wasbasedonaSwedishseries.10SPSS1 3.0forWindows(SPSSInc.,Chicago,IL,USA)andStata/SEversion8.0(StataCorpLP,Colle geStationTX,USA)wereusedtoperformthestatisticalanalyses,andthesignifi-cancelevel( avalue)wassetas0.05.184P.-H.Suetal
3.Results 3.1.GeneralfeaturesofthestudyparticipantsAtotalof1113maleparticipants,1036femalepa rticipants,andtheirparentswereenrolledfortheanalyses.Themeanandstandarddeviationfo rtallest/shortestsons,daughters,theirfathers,andmotherswere173.19(5.20)cm/168.30(5. 77)cm,161.65(4.87)cm/156.99(4.70)cm,168.34(5.59) cm,and157.04(4.85)cm,separately.Amongthesefamilies,theaveragenumbers(standardd eviation)ofsonsanddaughterswere2.42(1.25)and2.55(1.39),respectively,witharangeof1 e9sonsordaughters. 3.2.Predictingoffspring’sfinalheightbyparent’sheightThestatisticsforpredictingtallest/s hortestchildinthefamilybyparentalheightswithlinearregressionsarepre- sentedinTable1.Allthepvaluesfortestinginterceptsandslopesdifferingfromzerowerelesst han0.01.Father’sheightcontributedthemosttotallestson’sheightinthefamily(adjustedR2 Z0.20)andtheleasttotheshortestdaughter’sheightinthefamily(adjustedR2Z0.11). Nonetheless,mother’sheightcontributedthemosttotheshortestdaughter’sheightinthefami ly(adjustedR2Z0.18)andtheleasttotheshortestson’sheightinthefamily(adjustedR2Z0.13) . 3.3.Figuresforfittedregressionlinesandcomparisonwithexistingheightestimationmethod sFigures1AeHillustratetheeightscenariosforthedisti- butionofeachobservationandfittedlinearregressionlines.Forbettervisualimpression,verti calandhorizontalscalesforallthefigureswereunified(from150cmto200cm).Intermsofthe comparisonsofinterceptsandslopesamongmodelsofparentalheightspredictingtallest/sho rtestchildreninthefamily,alltheinterceptsweresignificantlydifferentfromeachother(allp< 0.01),butonlytheslopedifferencesbetweenfathers’heightpre-dictingtallestandshortestso ns(i.e.,0.42vs.0.37)revealedborderlinestatisticalsignificance(pZ0.07, detailsnotshown).Figures2AeDpresentthepredictingscenariosofmidparentalheightstota llest/shortestsonsanddaughterswithCMHandFPHregressionlinesasbenchmark.Whenwe usedtheTaiwanesemidparentalheighttopredictthetallestson’sheight(adjustedR2Z0.32),t heregressionlineandFPHlinealmostover-lappedfrom160cmto180cmofmidparentalheig ht(Figure2A).InFigure2,thepredictionlineofthecurrentstudyisparalleltotheFPHlinecons tantlyalltheway.Inaddition,CMHpredictionwasclosertothepresentstudyparticipantsatles sermidparentalheights,butitshiftedtowardtheFPHlineatgreatermidparentalheights. Figure2Cillustratesthepredictionofthecontributionofmidparentalheightstothetallestdau ghters’heightsinthestudyfamilies,comparingtheCMHandFPHlines.Theydifferthemosta tlowmidparentalheight,andthentheyreachacommonpredictionpointaroundthemidparent alheightof178cm.Finally,thepatternshowninFigure2DwasverysimilartothatinFigure2B. ThedistancebetweenthepresentstudylineandFPHdidnotaltermuchfromthemidparentalh eightof150e180cm.ItsCMHlinewasclosertothepresentstudylineatlessermidparentalheig ht,butshiftedtowardFPHlineatgreatermidparentalheight.Insummary,theFPHlineperfor
medabetterpredictionofthecontributionofmidparentalheightstotheheightsofthetallestso nsinthefamiliesofthepresentsudy,andtheachievementsvariedinotherscenarios.Toacertai nextent,specificpatternsintheobservationsamongtheTaiwanesepopulationforfinalheight predictionwithrespecttothetallest/shortestsons/daughterswerechar- acterizedbyourstudyresults. 4.DiscussionWithahugenumberofhealthyparticipants,wefoundthatfather’sheightcontrib utedthemosttothetallestsons’heightinthefamilyandmother’sheightcontributedthemostto theshortestdaghter’sheightinthefamily. Furthermore,inthepresentstudy,wecomparedthelinearregressionlinesusingTaiwanesemi dparentalheightstopredicttallest/shortestsons’anddaughters’heightswithCMHandFPHr egressionlines.Specifically,theFPHlineperformedabetterpredictiononcontributionofmi d-parentalheighttothetallestson’sheightinthefamilybutnotintheotherscenarios.Wefoundt hatthegenerationalTable1Predictingthetallest/shortestsons’anddaughters’finalheightsb yparentalheightswithsimplelinearregressions* VariablesSons’heightsincm(Y;nZ1113)Daughters’heightsincm(Y;nZ1036) TallestsonShortestsonTallestdaughterShortestdaughterFather(X)AdjustedR2Z0.20Adj ustedR2Z0.13AdjustedR2Z0.13AdjustedR2Z0.11Intercept(cm)(95%CI)102.40(94.12e 110.68)105.26(95.67e114.86)109.58(101.25e117.91)109.72(101.59e117.84) Slope(95%CI)0.42(0.37e0.47)0.37(0.32e0.43)0.31(0.26e0.36)0.28(0.23e0.33) Mother(X)AdjustedR2Z0.14AdjustedR2Z0.13AdjustedR2Z0.15AdjustedR2Z0.18Inte rcept(cm)(95%CI)109.26(100.09e118.43)99.82(89.58e110.06)101.14(92.24e110.04)9 2.33(83.90e110.77) Slope(95%CI)0.41(0.35e0.47)0.44(0.37e0.50)0.39(0.33e0.44)0.41(0.36e0.47) *Allpvalueslessthan0.01fortestinginterceptsandslopesdifferingfromzero. CIZconfidenceinterval. Finalheightpredictedbyparents’height185
increasesinheightsofTaiwaneseparentsandtheiroffspringswerebetweenthoseofHongKo ngChineseandSwedishpeople,allborninsimilaryearsofthe1970s.TheCMHmethodunder estimatedthefinalheight,whereastheSwedishFPHmodelmayoverestimateit.18Thecontri butionfromaparenttothetallest/shortestchildinthefamilyvaried.Nonetheless,theperforma nceofFPHmodelfavoredthepredictionofmidparentalheighttothetallestsoninafamilyamo ngthisTaiwanesepopulation. ThemajoradvantageofthepresentstudywastherelativelylargernumberofparticipantsinTai wan.Althoughfactorsaboutdietintake,physicalactivity,andpubertyage,whichalsocooper ativelydeterminefinalheight,werenotavailable,theapproachofinnovativeattemptsbypred ictingthefinalheightofthetallest/shortestboys/girlsprovidedinsightintothisissueinTaiwan esepopulation. Inclinicalsettings,themajorapplicationoftarget-heightassessmentonendocrineconditions wouldbeinFigure1(A)Thecontributionoffather’sheighttothetallestsoninfamily(YZ102.4 0t0.42X;adjustedR2Z0.20;pvalueforslope<0.01;nZ1113).(B)Thecontributionoffather’s heighttotheshortestsoninfamily(YZ105.26t0.37X;adjustedR2Z0.13;pvalueforslope<0. 01;nZ1113).(C)Thecontributionofmother’sheighttothetallestsoninfamily(YZ109.26t0. 41X;adjustedR2Z0.14;pvalueforslope<0.01;nZ1113).(D)Thecontributionofmother’she ighttotheshortestsoninfamily(YZ99.82t0.44X;adjustedR2Z0.13;pvalueforslope<0.01;n Z1113).(E)Thecontributionoffather’sheighttothetallestdaughterinfamily(YZ109.58t0.3 1X;adjustedR2Z0.13;pvalueforslope<0.01;nZ1036).(F)Thecontributionoffather’sheigh ttotheshortestdaughterinfamily(YZ109.72t0.28X;adjustedR2Z0.11;pvalueforslope<0.0 1;nZ1036).(G)Thecontributionofmother’sheighttothetallestdaughterinfamily(YZ101.1 4t0.39X;adjustedR2Z0.15;pvalueforslope<0.01;nZ1036).(H)Thecontributionofmother ’sheighttotheshortestdaughterinfamily(YZ92.33t0.41X; adjustedR2Z0.18;pvalueforslope<0.01;nZ1036).
determiningshortstatureandprecociouspuberty.Fortheissueofshortstatureofnon-GH-def ectpatients,ourstudyresultsprovideamorereasonablerangeoffinalheightsamonglocalpop ulation,ratherthanusingthebiaseduniversalCMHestimations.Meanwhile,forthepatients withGHdefect,ourresearchoutcomeisalsoessentialfortheevaluationofGHreplacementth erapyandfine-tuningonprescriptiondosage.Asforprecociouspuberty,becauseofearlyepip hysealplatedevelopmentresultinginitsprematureclosureandshortadultheight, gonadotropin-releasinghormoneanalogisusedfordelayingtheprogressandthenlettingpati entsapproachidealfinalheight.Thus,furtherunderstandingaboutthenormalrangeoffinalhe ightofTaiwanesepopulationfacilitatestheassessmentofgonadotropin-releasinghormonet reatmentsinclinics.Meanwhile,limitationsofthepresentresearchalsoexist.First,thisisaretr ospec-tivestudy,notalongitudinalone.Second,parentalheightwasself-reportedinquestion naires,whichmightresultininformationbias.Third,heightsamongsiblingswithinafamilyv ary.Iftherewasonlyoneboy/girlinafamily,he/sheservedasthetallest/shortestboy/girlinthe predictionmodelatthesametime.Themorethekidsinafamily,thebetteristhepossibilitytofin dparticipantswithextremeheights.Consequently,biggerfamiliesmightprovidemoreexcep tionallytallorshortparticipantsinthefinalheightpredictionmodelassuggestedbythepresent researc.Lastly,variablesofpotentialconfoundersaboutnutrition,menarcheageoffemaleoff spring,andexercisewerenotavailableinthelarge-scalestudyforanalyses, whichmightdecreasetheprecisionofpredictionofoffspring’sfinalheight. Astosuggestionsforfurtherstudiesinfuture,differen-tialeffectsofenvironmentalstressona dultheightbygenderareofmajorinterest.4Follow-upstudiesofpop-ulationsofdifferentrace smightbebeneficial,intermsofactivedatacollectionandfinalheightmeasurementsduringth estudyperiod.Furthermore,somemoredataon Figure1(continued). Figure2(A)Thecontributionofmidparentalheighttothetallestsoninfamily(YZ49.13t0.76 X;adjustedR2Z0.32;pvalueforslope<0.01;nZ1113),comparingtheFPHandCMHregressi onlines.(B)Thecontributionofmidparentalheighttotheshortestsoninfamily(YZ48.32t0.7 4X;adjustedR2Z0.24;pvalueforslope<0.01;nZ1113),comparingtheFPHandCMHregres sionlines.(C)Thecontributionofmidparentalheighttothetallestdaughterinfamily(YZ60.4 3t0.62X;adjustedR2Z0.25;pvalueforslope<0.01;nZ1036),comparingtheFPHandCMHr egressionlines.(D)Thecontributionofmidparentalheighttotheshortestdaughterinfamily( YZ57.69t0.61X;adjustedR2Z0.26;pvalueforslope<0.01;nZ1036),comparingtheFPHan dCMHregressionlines.CMHZcorrectedmidparentalheight;FPHZfinalheightforparental height.environmentalfactorswouldbehelpfultostudyissuesregardinggeneeenvironmenti nteractions.Twinstudiesoradaptationstudiescouldprovideadvancedinsightforsuchstudy.
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