295 International Journal of Scientific Study | March 2016 | Vol 3 | Issue 12

Fetal Biometry in Late 3rd Trimester for Gestational Age Indian StandardsHaridas Govinda Warrier1, K M Ashokan2

1Assistant Professor, Department of Obstetrics & Gynecology, Kannur Medical College, Kerala, India, 2Professor and Head, Department of Obstetrics & Gynecology, Kannur Medical College, Kerala, India

2. To develop a nomogram for the Indian population in relation to fetal biometry for gestational age in late 3rd trimester.

Inclusions Criteria• Onlycaseswithearlydocumentedgestationalagewere

included• Biparietal diameter (BPD) and femural length (FL)

werethetwomainparametersconsidered.Abdominalcircumference(AC)andheadcircumference(HC)alsonoted

• EstimatedfetalweightcalculationwasnotedfromthedefaultchartinUSGmachines.

Exclusion Criteria• Macrosomic babies outside 10th and 90th percentile

expectedforIndianstandardswereexcluded• Grosslyobesemothersexcludedduetolessclarityin

imaging• Casesof oligohydramnios• Casesof growthretardation/fetalanomalies• Otherparameterssuchashumerallength,binocular

INTRODUCTION

Most of the ultrasound (USG)machines incorporate achart of fetal biometry and gestational age byWesternstandards,e.g.,Hadlocket al.,1Sabbaghaet al.,2 Jeanty et al.,3,4 andCampbellset al.5EventhoughfetalageestimationbyUSGinlatepregnancyisnotareliablemethod,weintendtoframeachart for the3rd trimester fetal biometry by Indianstandards.Thereisdefinitedeviationof valuestothelowersideincomparisontowesterncharts.

Aim of Study1. Toestablishavariationinfetalbiometryin3rd trimester

in Indian population comparingwith thewesternpopulation

Original Article

AbstractIntroduction: Ultrasound (USG) study in antenatal patients is a very valuable tool especially when it comes to estimation of gestational age. Fetal biometry in late 3rd trimester differs very much in Indians compared to their western peers.

Objective: To frame out a fetal biometry chart in late 3rd trimester as per Indian standards and thereby eliminate the chance of being deceived by western charts in the case of term pregnancies.

Materials and Methods: A prospective study was conducted with study sample of 340 cases durisng a 12-month period. SPSS 16.0 Mann–Whitney U-test, the χ2 for qualitative and students t-test for quantitative variables. A P = 0.05 was considered significant.

Results: (1) There was definite discrepancy in Indian standard values of fetal biometry, being less than their western counterparts in late 3rd trimester, (2) average fetal weight of Indian babies at term was found 2.9 kg compared to 3.6 kg in western group.

Conclusion: There should be a fetal biometry chart by Indian standards incorporated in USG machines instead of relying on western charts.

Key words: Fetal biometry, Indian standards, Late 3rd trimester, Ultrasound study

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Month of Submission : 02-2016 Month of Peer Review : 03-2016 Month of Acceptance : 03-2016 Month of Publishing : 03-2016

Corresponding Author: Dr. Haridas Govinda Warrier, Department of Obstetrics & Gynecology, Kannur Medical College, Anjarakandy, Kannur - 670 612, Kerala, India. E-mail: haridasgwarriar@gmail.com

DOI: 10.17354/ijss/2016/168

Warrier and Ashokan: Late 3rd Trimester-Fetal Biometry Indian Standards

296International Journal of Scientific Study | March 2016 | Vol 3 | Issue 12

distance, and cerebellarmeasurements were notconsidered.

MATERIALS AND METHODS

Wehadastudyof fetalbiometryandfetalagecorrelationof babies beyond 32weeks of pregnancies inKannurMedicalCollegeOBGDepartment during a 12-monthperiodfromJuly1,2013,toJune30,2014,anddatafrom340casesduringtheperiodwerecollectedandanalyzed.

The cases selectedwas from booked antenatal casesattendingourclinicandalsofromthoseinourstudygroupforelectiveinductionat38weeks+gestation.

Most of these cases had 1st and 2nd trimester (around20weeks)USGreportswith reliabledocumentationof gestationalage.Thecasesincludedprimigravidaaswellasmultigravida.TheUSGwasdonebythefirstauthorwith19yearsexpertiseinobstetricUSGscanning.

ThemachineusedforthepurposewasWiproLogicAlpha200 and a curvilinear abdominal probewith 3.5MHzfrequencywasused.

RESULTS

ItsobservedthataveragebabyinIndiaweighs2.8-3kgby38-40weeks,whereasbywesternstandardsaveragebabyweightattermis3.6kg.

Itisobservedthatupto32weeksthebiometry-BPD,FL,AC,HCparametersdonotdiffermuchbetweenwesternandIndianstandards.From32weeksonward,therearelesser values for the above parameters in Indian babies compared to correspondingperiodsof Westernbabies.Thisdisparityisseenwidenedasageadvances.

The above disparity is explained perhaps by racial andethnic reasonsof Indianbabiesbeing less inweight totheirwesternpeers.Thefollowingchartof IndianversusWesternstandardsof fetalbiometryisself-illustrative.

Table1showingWesternversusIndianstandardsof fetalbiometryfrom32to40weeks.

FetalbiometryandestimatedfetalweightWesternversusIndianstandardsat37and38weeks(Figure1).

FetalbiometryandestimatedfetalweightWesternversusIndianstandardsat39and40weeks(Figure2).

Bythestudy,wehavedevelopedachartof fetalbiometryandestimatedfetalweightforgestationalage32-40weeks

inIndianpopulation.Ourstudycorrelateswellwiththestudy of Rajan et al.,6-81993both in fetal biometry andestimatedfetalweight.

Variationof estimatedfetalweightfrom32to40weeksinWesternversusIndianstandards(Figure3).

DISCUSSION

The duration of pregnancy is classically described inmenstrualagebyadding40weekstothe lastmenstrualperiod(Nagle’srule).Theclinicalapplicationof USGinobstetricswasintroducedandpopularizedbyIanDonaldinGlasgowin1958.Nowadaysthereal-timeimagingwithhigh-resolutionprobeshasrevolutionizedantenatalUSGstudy.ThemosteffectivewaytodatepregnancyisbyUSGeven though late 3rdtrimesterscanforgestationalageisnot that reliable.

The variation in gestational age calculation byUSG,1st trimester ± 7 days, 2nd trimester ± 10-14 days,3rdtrimester±14-21days.

Theformulaforestimatedfetalweightshowsanerrorupto±10%of thepredictedvalue.

In our study, we have compared our findings takingHadlock et al.,9 as themainwestern representative asthis is thedefaultchartprovidedinmostof theUSGmachines.

AlltheWesternstandardchartsshowaBPDat40weeksrangingfrom95to98mm(babyweight-3.5-4kg)whereasRajan et al.,andourstudy(Indianstandards)showaverageBPD90mmwithestimatedfetalweight(EFW)around2.9-3kg.Hence,unlessthereportingsonologisttakethisintoconsideration,a40weeksIndianbabymaybereportedas36-37weeksbyWesternstandards.ThisdiscrepancyisthereinFL,HC,andACaswell.

Table 1: Western Vs Indian chart for Fetal biometry-32 to 40 weeksWeeks BPD (cm) FL HC AC EFW (kg)

West India West India West India West India West India32 7.9 7.9 6.3 6 29.7 28.5 28 26.8 1.81 1.7233 8.2 8 6.5 6.1 30.4 28.8 29 28.2 2.01 1.934 8.4 8.1 6.6 6.3 31.2 29.2 30 28.7 2.22 1.9935 8.6 8.3 6.8 6.6 31.8 30 30.9 29.6 2.43 2.1536 8.8 8.5 7 6.7 32.5 30.9 31.8 30.1 2.65 2.337 9 8.6 7.2 6.9 33.6 31.3 32.7 31.3 2.89 2.4538 9.1 8.7 7.3 7 33.6 31.5 33.6 32.5 3.15 2.6239 9.3 8.8 7.5 7.1 34.1 32.1 34.5 32.7 3.36 2.7840 9.5 9 7.6 7.2 34.5 32.9 35.4 33.4 3.52 2.96EFW: Estimated fetal weight, BPD: Biparietal diameter, FL: Femural length, HC: Head circumference, AC: Abdominal circumference

Warrier and Ashokan: Late 3rd Trimester-Fetal Biometry Indian Standards

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Figure 1: Fetal biometry and estimated fetal weight 37 and 38 weeks Western versus Indian

Figure 2: Fetal biometry and estimated fetal weight 39 and 40 weeks Western versus Indian

Figure 3: Variation of estimated fetal weight

Warrier and Ashokan: Late 3rd Trimester-Fetal Biometry Indian Standards

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Thestatusof placentalgradingAFIandBPPhastobeconsidered in this context.A biophysical profile and aDopplerstudy inhigh-riskpregnancieswereconsiderednear term.

Therearemanytablesandnormogramsthatdescribethenormalgrowthof variousfetalparameters.Thenormogramsdevelopedforaparticularpopulationneednotbetrueforanotherpopulationespeciallyinlate3rdtrimesterandweare highlighting the above point in our study.

CONCLUSION

Newborn in India weighs <3 kg, whereasWesternnewbornsweigh3.6kginanaverage.Hencetowardterm,there is a discrepancy in all fetal biometric parametersbetween Indian babies and theirWestern counterparts.However,theEFWshowsarealvalueas itdependsontheactualbiometryrecorded.BPDandFLarethebestparameters for fetal age in late pregnancy, but the fetalweight ismainly reflected by theAC.An experiencedsonologistandamachinewithgoodresolutionareamustforatrueevaluation.Inourstudy,anaveragegaininweightof 160gperweekisobservedfrom36to40weeks.Alwaysareliable1st trimesterscanwillhelpa lotwhenthere isconfusion.

Hence,atleast,someof theobstetricianswhoareunawareof theabovesituationmaybedeceivedbysonologyreportdoneoutside.Hence,eventhoughalatetrimesterscanisnotthatreliableforgestationalage,theobstetricianshouldbealwaysvigilantabouttheabovescenario.

WemakeaconclusionthatallthemachinesshouldhavesoftwareforfetalbiometryandestimatedfetalweightwithIndian standards as framed out in our study.

ACKNOWLEDGMENT

WeexpressoursinceregratitudetotheEthicalCommittee,KannurMedicalCollegeforgrantingpermissiontoconductthestudy.Wealsoexpressourgratitudetothemanagementforfundingtheprojectandgrantingpermissiontopublishthearticle.

The help of associate professorsDr. CKRajammaandDr. Smitha Santhosh in the above study is alsoacknowledged.

REFERENCES

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3. Jeanty P. Fetal biometry. In: Fleisher AC, editor. The Princples and Practice of Usage in Obstetrics and Gynaecology. New Jersey, USA: AE Prentice-Hall International Edition; 1991. p. 93.

4. Chervanat FA, Jeanty P, Hobbins JC. Current status of fetal growth and assessment seminar. Banglore; 14-16 July, 1986. p. 423.

5. Campbell S. Fetal growth. Clin Obstet Gynaecol 1974;1:41-65.6. Rajan R. In: Infertility Committee of FOGSI, editor. Ultrasound Dating in

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How to cite this article: Warrier HG, Ashokan KM. Fetal Biometry in Late 3rd Trimester for Gestational Age Indian Standards. Int J Sci Stud 2016;3(12):295-298.

Source of Support: Nil, Conflict of Interest: None declared.