Comparison of growth curves in very low birth weight preterm infants after hospital discharge

Monitoring preterm infants’ growth is essential to ensure the best prognosis for their growth and development. We aimed to compare growth curves in very low birth weight preterm infants after hospital discharge. In this retrospective longitudinal study, 178 preterm infants’ growth was assessed by z-scores for weight for age and length to age and compared between Fenton and Kim and Intergrowth-21st charts from hospital discharge until 50 weeks postnatal, and between Intergrowth-21st and WHO charts, 50 and 64 weeks postnatal. The Kappa test was used to evaluate the agreement of the number of cases classified above or below the −2 Z-score concerning weight-for-age and length-for-age indicators to each proposed curve. Our results found that the agreement between Fenton and Kim and Intergrowth-21st curves was almost perfect for most of the weeks investigated, except 35–38 (k = 0.79) and 47–50 (k = 0.61) weeks postnatal. When evaluating the agreement between WHO and Intergrowth-21st, it was substantial for most of the weeks investigated, except for 55–58 and 69–64 weeks postnatal, in which the agreement was almost perfect (k = 0.84; k = 0.81, respectively). Furthermore, we observed that Fenton and Kim curve identified 8.4% and WHO, 5.8% more cases of preterm infants below −2 z than Intergrowth-21st.