Prethreshold retinopathy in premature infants with intrauterine growth restriction

Abstract

Aim: To determine, among very preterm newborns, whether those who are growth-restricted are at increased risk of retinopathy of prematurity (ROP), and to explore whether the mixed findings of prior studies are the consequence of sampling based upon birthweight instead of gestational age.

Methods: Using data from the ELGAN Study, we created logistic regression models of prethreshold ROP risk to adjust for confounders and calculate odds ratios and 99% confidence intervals. We created scatter plots to display the gestational age/birthweight relationship in infants enrolled in studies with different selection criteria.

Results: Low gestational age [23-24 weeks, OR 11.6 (2.9, 47); 25-26 weeks, 8.1 (2.1, 32)] and severe growth restriction [birthweight Z-score <-2, OR 9.1 (1.1, 76)] were associated with increased risk of prethreshold ROP. We documented in scatter plots that a sample defined by birthweight has an excess of gestationally older, severely growth-restricted newborns.

Conclusion: In this sample, low gestational age and severe growth restriction were associated with increased risk of prethreshold ROP.

Keywords: Extremely low gestational age newborn; Growth restriction; Prematurity; Retinopathy; Retinopathy of prematurity.

Figure 1

These scatterplots demonstrate how birth weight and gestational age distributions of newborns differ depending on enrollment criteria. The top scatterplot is of newborns enrolled on the basis of a birth weight < 1500g(14). All infants whose gestational age at birth is > 33 weeks are in the lowest decile of birth weight for gestational age. The bottom scatterplot is of newborns enrolled on the basis of a gestational age < 28 weeks (9), which avoids the excess of growth-restricted infants seen in the top scatterplot. The lines are regression lines for each sample.