Post discharge growth assessment in preterm infants: implications of adopting the WHO standards.

Introduction: The WHO standards have been used as a gold standard for growth assessment in preterm infants since 1986. The introduction of the WHO standards in Argentina could improve detection of sub-optimal growth.

Objective: To compare the proportion of growth retardation in terms of weight, body height and head circumference in preterm infants with a birth weight less than 1500 g (VLBW) assessed according to the WHO standards and the Sociedad Argentina de Pediatría (SAP) standards.

Population And Methods: Cohort study in VLBW newborn infants. Measurements included were weight, height and head circumferences measured at 40, 53, 66, 79 and 92 postmenstrual weeks (±1 week). Sex was recorded as an independent outcome measure for both standards (WHO and SAP). Mean Z scores were analyzed for both standards using Student's test, and the difference of proportions was assessed using the c2 test (OR; 95% CI).

Results: Two hundred and four infants were included. No differences were observed in anthropometric outcome measures at birth by sex. A greater growth was seen in terms of weight and height as per the SAP standards compared to the WHO standards, which was more marked in male infants than female infants, and which diminished around their first year of life. Growth retardation in terms of height was observed in both males and females assessed with the WHO standards. No differences were observed in head circumference. A higher proportion of patients with a weight below 2 standard deviations at 3 months old was found as per the WHO (p < 0.01; OR: 0.36; 95% CI: 0.150.78), but that was not the case with height and head circumference.

Conclusions: This study allows to suggest that changing the standards does not imply a significant modification in our follow-up practice over the first year of life of an infant.