Association of Average Day Length during Early Gestation with Treated Retinopathy of Prematurity in Black Premature Infants: A Multicenter Study.

Abstract

Purpose: Previous studies suggested the presence of a melanopsin-dependent light response during early gestation in the fetal mouse that affected the subsequent development of retinal neurons and vasculature. Supporting this hypothesis was a single center study that showed lower light exposure during early gestation, estimated by average day length (ADL), was associated with a higher risk of severe retinopathy of prematurity (ROP) warranting surgery. The purpose of this study was to analyze a multicenter cohort of premature infants for an association between ADL during early gestation and treated retinopathy of prematurity (TROP).

Methods: In 2090 premature infants (11 centers), multiple logistic regression analysis (MLRA) of predictive variables for an outcome of TROP included ADL during days 61-90 after conception (ADL61-90).

Results: Increasing birth weight & gestational age and black race were associated with a lower likelihood, while male gender was associated with a higher, likelihood of TROP. Multiple birth status was not predictive of outcome. While ADL61-90 was not significantly associated with TROP in the overall population (p=0.104), subgroup analysis for 530 black infants showed that each additional hour of ADL61-90 (range: 8.98 to 15.4 h) was associated with a 31.5 % lower likelihood of developing TROP (Odds Ratio: 0.685, p = 0.003). The addition of WINROP alarm status, a marker of "illness severity", to the MLRA did not eliminate ADL61-90 as a significant predictor.

Conclusions: The association of lower ADL with TROP occurred only in black infants and may be due to greater attenuation of light to a critical threshold of response by the mother's darker skin pigment and/or involvement of a different pathway for light-induced vascular development. Current treatment at the less severe type 1 prethreshold ROP may have masked the previously reported association of lower ADL with more severe ROP, i.e. classic threshold, in a different cohort of infants. There may be a role for light therapy in early gestation to reduce the risk of TROP among black premature infants.