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Estimation of Gestational Age, Using Neonatal Anthropometry: A Cross-sectional Study in India
Thawani, Rajat; Dewan, Pooja; Faridi, M.M.A.; Arora, Shilpa Khanna & Kumar, Rajeev
Abstract
Prematurity is a significant contributor to neonatal mortality in India. Conventionally, assessment of gestational
age of newborns is based on New Ballard Technique, for which a paediatric specialist is needed.
Anthropometry of the newborn, especially birthweight, has been used in the past to predict the gestational
age of the neonate in peripheral health facilities where a trained paediatrician is often not available.
We aimed to determine if neonatal anthropometric parameters, viz. birthweight, crown heel-length,
head-circumference, mid-upper arm-circumference, lower segment-length, foot-length, umbilical nipple
distance, calf-circumference, intermammary distance, and hand-length, can reliably predict the gestational
age. The study also aimed to derive an equation for the same. We also assessed if these neonatal anthropometric
parameters had a better prediction of gestational age when used in combination compared to
individual parameters. We evaluated 1,000 newborns in a cross-sectional study conducted in Guru Teg
Bahadur Hospital in Delhi. Detailed anthropometric estimation of the neonates was done within 48 hours
after birth, using standard techniques. Gestational age was estimated using New Ballard Scoring. Out of
1,250 consecutive neonates, 1,000 were included in the study. Of them, 800 randomly-selected newborns
were used in devising the model, and the remaining 200 newborns were used in validating the final model.
Quadratic regression analysis using stepwise selection was used in building the predictive model. Birthweight
(R=0.72), head-circumference (R=0.60), and mid-upper arm-circumference (R=0.67) were found
highly correlated with gestation. The final equation to assess gestational age was as follows: Gestational
age (weeks)=5.437×W–0.781×W2+2.815×HC–0.041×HC2+0.285×MUAC–22.745 where W=Weight,
HC=Head-circumference and MUAC=Mid-upper arm-circumference; Adjusted R=0.76. On validation, the
predictability of this equation is 46% (±1 week), 75.5% (±2 weeks), and 91.5% (±3 weeks). This mathematical
model may be used in identifying preterm neonates.
Keywords
Anthropometry; Equation; Gestational age; New Ballard Score; Newborn; India
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