Intergrowth 21 Versus Fenton 2013 Growth Charts: Congruence in Assessing the Birth Size and the Proportion of Extra-uterine Growth Restriction in Preterm Babies

Intergrowth-21st and Fenton 2013 growth charts are used for postnatal growth monitoring in preterms. There is no international consensus on which graph to refer to and why. This study is a local validation, of which graph would be plausible for the Indian population to detect small-for-gestational-age (SGA) and extra-uterine growth restriction (EUGR) babies, abetting in the settlement of this ambiguity. The primary objective was to compare the Intergrowth-21st with Fenton 2013 growth charts for birth size classification and to detect the proportion of EUGR in preterms. The secondary objective was to assess the proportion of comorbidities in SGA babies by both these graphs. The design of the study was a prospective comparative observational study. All preterm newborns (24–<37 weeks of gestation) admitted to the neonatal intensive care unit of Noble Hospital and Research Center, Maharashtra, were the participants. Weight, length, and head circumference were plotted on Intergrowth 21 and Fenton growth charts at birth and at 4 weeks of age or at 36 weeks of postmenstrual age whichever is later. Corresponding Z-scores and percentiles were calculated electronically from their respective online software. the reliability of Intergrowth-21st when compared to Fenton 2013 growth charts in assessing the birth size was better, and detection of the proportion of EUGR in preterm babies was better with Fenton charts. A total of 429 preterm babies with a mean gestational age of 33.3 ± 2.4 weeks were included in the study. Fenton (67.1%) overestimated the proportion of EUGR when compared to Intergrowth-21st (18.6%) which was statistically significant (P < 0.001). On the contrary, although the proportion of SGA babies detected was higher with Intergrowth-21st (29.8%) when compared to Fenton (19.6%), there was moderate-to-high statistically significant agreement observed between the two growth charts in detecting SGA babies (Kappa = 0.716, P < 0.001). The proportion of comorbidities did not vary significantly among the SGA babies between the growth charts (P > 0.05). Fenton overestimates EUGR when compared to Intergrowth-21st, whereas both the growth charts are equally good in identifying SGA babies with no differences in the comorbidities detected. Intergrowth-21st standards look more pertinent for growth monitoring in the current study setting for Indian preterm babies.