Indian J Pediatr 1989 ; 56 : 115-119

Determination of Gestational Age : Comparative Accuracy of Different Methods

S.C. Goyal, S.K. Tak and B. Bhandari

Department of Pediatrics, R.N. T. Medical College, Udaipur 313001.

One hundred new-born infants were studied in an attempt to test the accuracy of selected methods of post-natal assessment of gestational age. The Finnstrom method using seven external characteristics was found to be relatively more accurate both in preterm and term infants. Dubowitz and Cappuro method were accurate in premature infants only. However in a limited number of post-term infants Cappuro method yielded better results. The Finnstrom method can be recommended for routine assessment of gestational age.

Key words : Gestational age ," Finn.s'trom ; Dubowitz ," Parkin ; Cappl~o

In thc newborn infant it is essential to know the correct gestational age particularly in the low birth weight (LBW) infants, so as to evaluate the risk of morbidity and mortal'ity. Knowledge of gestational age of newborn may modify modalities of c~u'e.

It is difficult to determine the correct gestational age, particul~trly when the date of last menstrual period (LMP) is not known. In past all low birth weight infants were considered as premature. About 30 to 40

percent of babies in India are LBW. These include both preterm and term small for gestational age babies. About 8-10 percent of Indian babies arc born preterm, others being term-small for date 1.

The gesu:tional age can bc calculated from the date of LMP, but this may not be known with certainty or may provide

misleading information due to irregularl periods, post-conceptional bleeding, use of oral contraceptives and conceivement in the pericxl of lacu~tional amenorrhoea.

Various clinical scoring system/ methods 2-21 have been developed for postnatal assessment of gesmtional age by studying various physical and neurological characteristics of new-born.

Since Dubowi~ and coworkers 13 published their technique of gesmtionat age assessment, many investigators have attempted to design shorter and more easily applied methods 14-21 claiming to give equally accurate results. These include : Parkin 17, Finnstrom 18 and Cappuro 20. The present study was undcm~ken to asscss the relative accuracy of these methods, i

MATERIAL AND METtlOI)S Reprhlt requests : Dr. Suresh Goyal, 1 Oa 21, Sector

No. 5, lliran Magri, Udaipur 313 001, Rajasthan One hundred newborn infants delivered

116 TIIE INDIAN JOURNAL OF PEDIATRICS Vol. 56, No. 1

at Zanana Hospital, Udaipur were studied. Only those infants were included whose mothers had normal menstrual periods, no history of intake of oral contraceptives before conception with exact knowledge of their last menstrual period.

Infants were examined in neutral thermal environment, between 12-24 hours of postnatal age. The clinical examination and calculation of gcstational age was carried out as described in the original methods.13,17,18, 20 For each infant gestational age was calculated by throe different workers and an average of three was taken.

RESULT

The gestational age (GA) calculated from the mother's dates (LMP) was used as the standard (actual), against which that from the various methods was compared. The infants were classified into three gestational

age groups : Preterm < 37 weeks ; term 37-42 weeks ; post term > 42 weeks.

Mean gestational age together with S.D. and S.E. was calculated. For su/tistical significance student 't' test was applied and a 'p' value o f < 0.05 was considered signi- ficant. Results are shown in Table I.

Finnstrom's method was observed to be accurate in assessing maturation in both full term as well as prcterm infants. Dubowitz method yielded good results in premature infants only. Capurro method was accurate in calculating gestational age in both preterm ,and post term infants ; however this method was not found to be accurate in calculating gestational age in majority of the term-infants.

DISCUSSION

Assessment of G.A. in low birth weight infants is difficult when exact dates are not

Table I. Gestational age of infants classified in three sub-groups

Gestational age Actual gestational Dubowitz Finnstrom Parkin Cappuro age method method method method

Group I : (< 37 weeks, N = 43) Mean 32.63 32.65 32.89 33.45 32.34 SD 2.62 3.16 2.64 2.51 2.87 SE 0.339 0.475 0.402 0.382 0.437 p value - - NS NS < 0.05 NS

Group II : (37--42 weeks, N = 52) Mean 39-23 38.55 39.1 38.25 38.33 SD 1.22 1.75 1.61 1.70 1.65 SE 0.162 0.242 0.223 0.235 0.228 p value - - < 0.001 NS < 0.001 < 0-001

Group HI : (> 42 weeks, N = 5) Mean 42.20 41.00 41-78 41.60 41.80 SD 0.40 0.00 0-39 0.37 1.16 SE 0.178 0.00 0.174 0.165 0.518 p value - - < 0.001 < 0-005 < 0.01 NS

N.S. = Not Significant

GOYAL ET AL : DETEI~MINATION OF GESTATIONAL AGE 117

known. The Dubowitz methixP 3 is fairly accurate and widely used, is very elaborate and time consuming, and at times unsuited for use in sick newborn. It cannot be used in early hours after birth as tone and reflexes are depressed. The neurological criteria are not easily reproducible and show marked interpersonal variations. The abbreviated

methods have attempted to improve upon this situation by excluding the neurological criteria.

The Parkin method 17 uses only four external characteristics thus making it easy for practical use. However it has certain limitations : three of the characteristics, skin colour, texture and breast size can be

Table lI . Criteria used in gestational age determination by various authors

METltOD

Criteria Dubowitz FinrLvtrom Parkin Cappuro Cappuro (A) (B)

N Posture + E Square Window + U Ankle dorsiflexion + R O Ann recoil + L Leg recoil + O Popliteal angle + G Heal to ear + I Scarf sign 5- C Head lag 5- A Ventral L Suspension +

P Edema + H Skin texture + Y Skin colour 5- S Skin opacity + I l_,anugo + C Plantar crease + A Nipple formation + L Breast size + C Ear form + R Ear firmness + T Genitals + E Scalp hair R Finger nails I A

+

5-

+

+

+

5-

+

+ +

+ +

5-

+ +

+ +

No. of criteria used 21 7 4 5 6

118 THE INDIAN JOURNAL OF PEDIATRICS Vol. 56, No.l

influenced by placental insufficiency and intrauterine growth retardation independant of period of gestation. Further a difference by a score of one at lower G.A. will change the G.A. by as much as three weeks. G.A. above 295 days (42.1 weeks) cannot be calculated by this method.

The Cappuro A method20 has similar limitations and the method B incorporates additional two neurological criteria, In Cappuro B method it is not possible to calculate gestational age below 204 days (29 weeks) and in Cappuro method B gestational age upto 313 days (44-7 weeks) can be calculated. Thus Cappuro method is more suited if post maturity is suspected. However since the number of post-term infants studied was small, therefore inter-pretation of results in this group has to be guarded.

The Finnstrom method 18, utilizing seven external characteristics, is easy to remember, takes minimum time, can be used in early hours after birth, and can be used in sick new born infant. It is very accurate ,as is evident from the present study. Therefore this method can be recommended for routine assessment of gestational age particularly in preterm and full term infants.

References

1. Singh M. Care of the newborn. ~t3rd Edn.] New Delhi : Sagar Publications, 1985 ; !24-139

2. Saint-Anne Dargassies S. La-Maturation neurologiue du premature. Et Neonet 1955 ; 4 : 71-77

3. Prechfl HFR, Beintema D. The neurological examination of the full term new born infant. London : Heinemann/Spastics International Publication, 1964 ; 51-56

4. Robinson RJ. Assessment of gestational age by neurological examination. Arch Dis Child 1966 ; 41 : 437-447

5. Koenigsbcrger MR. Judgement of Foetal age : Neurological evaluation, Pediatr Clin North Am 1966 ; 13 : 823-82,3

6. Amiel-Tison C. Neurologica[ evaluation of maturity of newborn infant. Arch Dis Child 1968 ; 43 : 89-93

7. Farr V, Kerridge DF, Mitchell RG. The value of some external characteristics in the assessment of gestational age at birth. Dev Med Child Neurol 1966 ; 8 : 657-660

8. Farr V, Mitchell RG, Neligan GA, Parkin JM. The definition of some external characteristics used in the :assessment of gestational age in file newborn infants. Dev Med Child Neurol 1966 ; 8:507-511

9. Usher R, Mclean F, Scott KE. Judgement of fetal age II, Clinical importance of gestati0nal age and an objective method for its assessment. Pediatr Clin North Am 1966 ; 13 : 835-837

10. Saigal S, Srivastava JR. Newer clinical criteria ofprematurity. IndianPediatr 1968 ; 5 : 369-378

11. Amiel-Tison C. Neurological evaluation of maturity of newborn infams. Arch Dis Child 1968 ; 43 : 89-93

12. Farr V, Mitchell RG. Estimation of gestational age in . the newborn infant. Comparison between birth weight and maturity scoring in infants premature by weight. Am J Obst Gynecol 1969 ; 103 : 380-383

13. Dubowitz LMS, Dubowitz V,. Goldberg C. Clinical assessment of gestational age in the newborn infant. J Pediatr 1970 ; 77 : 1-10

14. Lubchenco LO. Clinical estimation of gestational age. Pediatr Clin North Am 1970 ; 17 : 125-145

15. Ballard J, Kazmaier K, -Dr iver MA simplified assessment of ge,;tational age. Pediatr Res 1977 ; 11:374-379

16. Singh M, Razdan K, Ghai OP. Modified Scoring system for assessment of gestational age in the newborn. Indian Pediatr 1975 ; 12 : 31-316

GOYAL ET AL : DETEI~MINATION OF GESTATIONAL AGE 119

17. Parkin JM, Hey EN, Clowes JS. Rapid assessment of gestational age at birth Arch Dis Child 1976 ; 51 �9 259-263

18. Finnstrom O. Studies on maturity in newborn infants. Acta Ped Scand 1977 ; 66 : 601-604

19. Hittner HM, Hirsh NJ, Rudolph AJ. Assessment of gestatiomd age by examination of the anterior vascular capsule

of the lens JPediatr 1977 ; 91": 455-458 20. Cappuro H, Koniechezky S, Tonseca D,

Caldeyro B~trchia R. A simplified method for diagnosis of gestational age in newborn infants. J Pediatr 1978 ; 93 : 120-122

21. Narayan I, Dua K, Gujral VV et al. A simple method of assessment of gestational age in newborn infant. Pediatrics 1982 ; 69 : 27-32

Super ORS

Many studies have shown that adding glycine to standard ORS does not produce an enhanced absorption of fluid. The study by Pizarro et al did not show evidence of diuresis caused by the glycine, or a rise in BUN, two drawbacks of glycine reported elsewhere.

WHO reports that early results from an alanine-fortified ORS are much promising, suggesting an enhancement of absorption of as much as 40 percent. We await final reports from those studies, as well as some cost data to show how much the additional amino acid will add to the price of ORS.

In the meantime, we should all keep in mind that food is the most practical and cheapest "Super ORS". Giving food, like rice, along with ORS will enhance fluid absorption and reduce the duration of diarrhea, i.e., "stop the diarrhea", which is what the mothers want. Thus, feeding is a pert of the rehydration treatment, part of the treatment of the diarrhea itself, as well as a nutritional benefit for the child. If we could get more doctors, and mothers, to think of feeding as part of their "medicine" for the diarrhea, part of the prescription, we would probably see no additional benefit from adding alanine or whatever purified food constituent to the patient's intake.

AbNm~scl front Pizaroo D et. ~. J. Pediaa" Gastroenterol & Nu~'. 1988 ; 7 : 411-416

Nor~rup R. Tech Literature. update Pritech. 1988 ; 3, No. 7 : 3-4