A study on correlation between gestational age and foot length measurements

 

 

Abstract              Background: The comparison with determination of CHL and birth weight, the foot length measurement is more convenient in preterm sick neonates, in special care units without disturbance to such infants. It could also be useful in deriving the surface area more accurately than from birth weight alone for the calculation of drug doses and fluid requirements in preterm. Methodology: All the singleton live born babies born in the hospital were examined with in 48 hours of birth. Gestational age was calculated by enquiring into 1^st day of mothers last menstrual period and will be subsequently confirmed by New Ballard Score.If any disparity of more than 2 weeks between gestational age by enquiring LMP and by NBS, were excluded from the study. Results: The mean foot length of the babies analyzed was 8.03 cm, with the SD of 0.80 cm. It was found that foot length was correlated well with the gestational age. Conclusion: In the derived normogram based on foot length and gestational age it was observed that there is a linear relationship of the foot length with increasing gestational age.

Keywords: Gestational Age, Foot Length Measurements, normogram

 

INTRODUCTION

In preterm, the foot length correlated with all three indices i.e. CHL, HC and birth weight. Foot length has a positive linear correlation with other body measurements in a neonate and has the highest correlation in preterm babies with CHL.¹ When applied to neonates it was found to correlate with 95% of the babies. Hence, because it is easy, requiring less handling and less disturbing to the neonate, foot length is a better screening tool. Very few studies have been done on determining the usefulness of foot length. Significant relationship between foot length and other parameter has been observed in these studies.² The highest correlation in term small for gestational age and term AGA babies for foot length was with HC indicating that foot length and HC are affected in a similar fashion in term neonates.³

The comparison with determination of CHL and birth weight, the foot length measurement is more convenient in preterm sick neonates, in special care units without disturbance to such infants. It could also be useful in deriving the surface area more accurately than from birth weight alone for the calculation of drug doses and fluid requirements in preterm. Hence foot length is a new and potentially useful measurement in the neonate.⁴

 

METHODOLOGY

All the singleton live born babies born in the hospital were examined within 48 hours of birth. Gestational age was calculated by enquiring into 1^st day of mothers last menstrual period and will be subsequently confirmed by New Ballard Score. If any disparity of more than 2 weeks between gestational age by enquiring LMP and by NBS, were excluded from the study. Their gestational ages ranged from 29 to 42 weeks. As there were few babies in less than 30 weeks gestation they were grouped together. Newborns were subjected to the following anthropometric measurements within 48 hours of birth by standard techniques.

Birth weight: Babies were weighed naked immediately after birth on lever actuatedweighing scales to the nearest 50 g. The weighing machine was checked periodically by known standard weights.

Crown heel length: The baby was placed supine on an infantometer. The head is heldfirmly in position against a fixed upright headboard. Legs are straightened keeping feet at rights to legs with toes pointing upwards. A free footboard is brought into firm contact with the baby's heels. Length of the baby is measured from a scale, which is set into the board.

Head circumference: A flexible non-stretchable fiber glass tape was used. The headcircumference in the largest dimension around the head (the occipito-frontal circumference) was obtained with a tape placed snugly above the ears. The tape is placed over the mid forehead and is extended circumferentially to include the most prominent portion of the occiput .The measurement was taken to the nearest 0.1cms.

Foot length: A wooden scale was used with 0.1cm division and it was fixed againstthe foot and the distance from the heel to the tip of great toe of the left foot was measured to the nearest of 0.1cm, after straightening the foot.

INCLUSION CRITERIA

All the singleton live born babies born in hospital were included in the study.

EXCLUTION CRITERIA

1. All twin babies.
2. Intra uterine deaths and still born babies.
3. Babies with gross congenital anomalies.
4. Babies born to mothers with condition likely to influence fetal growth i.e. hypertensive disorders of pregnancy, gestational diabetes mellitus, chronic infections and illnesses are excluded.
5. Babies whose gestational age could not be accurately assessed i.e. >2 weeks difference between obstetrical and clinically assessed gestational age.

 

RESULTS

The mean foot length of the babies analyzed was 8.03 cm, with the SD of 0.80 cm.

It was found that foot length was correlated well with the gestational age.

(r = 0.523, p < 0.0001)

In the derived normogram based on foot length and gestational age it was observed that there is a linear relationship of the foot length with increasing gestational age. There is increase in the foot length with the increasing gestational age, which started declining after 40 weeks gestations.

 

 

 

 

 

 

 

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