Diagnostic value of newborn foot length to predict gestational age


Paediatrica Indonesiana, Vol. 57, No. 4, July 2017

Diagnostic value of newborn foot length to predict gestational age

Mutia Farah, Bambang Soebagyo, Dwi Hidayah




Background Identification of gestational age, especially within 48

hours of birth, is crucial for newborns, as the earlier preterm status is detected, the earlier the child can receive optimal management. Newborn foot length is an anthropometric measurement which is easy to perform, inexpensive,  and potentially efficient for predicting gestational age.

Objective To analyze the diagnostic value of newborn foot length in predicting gestational age.

Methods This diagnostic study was performed between October

2016 and February 2017 in the High Care Unit of Neonates at Dr. Moewardi General Hospital, Surakarta.  A  total of 152 newborns were consecutively selected and underwent right foot length measurements before 96 hours of age. The correlation between newborn foot length to classify as full term and gestational age was analyzed with Spearman’s correlation test because of non-normal data distribution. The cut-off point of newborn foot length was calculated by receiver operating characteristic (ROC) curve and diagnostic values of newborn foot length were analyzed by 2 x 2 table with SPSS 21.0 software.

Results There were no significant differences between male and female newborns in terms of gestational age, birth weight, choronological age, and newborn foot length (P>0.05). Newborn foot length and gestational  age had a significant correlation (r=0.53; P=0.000). The optimal cut-off newborn foot length to predict full term status was 7.1 cm. Newborn foot length below 7.1 cm had sensitivity 75%, specificity 98%, positive predictive value 94.3%, negative predictive value 90.6%, positive likelihood ratio 40.5, negative likelihood ratio 0.25, and post-test probability 94.29%, to predict preterm status in newborns.

Conclusion Newborn foot length can be used to predict gestational age, especially for the purpose of differentiating between preterm and full term newborns. [Paediatr Indones. 2017;57:181-6; doi: http://dx.doi.org/10.14238/pi57.4.2017.181-6 ].

Keywords: preterm; foot length; gestational age; newborn

From the Department of Child Health,  Sebelas  Maret  University Medical School/Dr. Moewardi General Hospital, Surakarta,  Central Java, Indonesia. Reprint requests to: Mutia Farah. Department of Child Health, Sebelas Maret  University Medical  School/Dr. Moewardi Hospital. Ruang Angrek IV RSUD Dr. Moewardi, Jl. Kolonel Sutarto No 132, Jebres, Kota Surakarta. Phone +62271-634634 ext. 408/ +62271  666866. Fax.+62271-664598, Email: ppdsika@gmail.com.