Retinopathy of Prematurity Risk Nearly Doubles Per 1-Week Reduction of Gestational Age

ROP Exam on baby.
UNDATED PHOTO: At Bascolm Palmer Hospital, Dr. Steve Christiansen performs an ROP (Retinopathy of Prematurity) exam on a premature ICU baby 1992 in Miami, Florida. Premies are at high risk for retinal problems.It is widely believed that sight is the most complex of the five senses. It is also often thought to be our most valued, so much so that scientists are engaged in a constant endeavor to fully understand sight so that they may better fight the seemingly endless battle against blindness. (Photo by Joe McNally/Getty Images)
The condition is also 1.8 times more likely per 100-gram decrease in birth weight, a study shows.

Odds of retinopathy of prematurity (ROP) increase 1.4 times per week reduction in gestational age (GA) and 1.8 times per 100-gram decrease in birth weight (BW), researchers found in a study published in Neonatology.

Both countries’ criteria of GA and BW for screening infants with prematurity for ROP and strength of association between demographic risk factors and ROP development vary. 

Researchers searched MEDLINE, EMBASE, and Cochrane for population-based studies published in English between 2010 and May 2020 regarding the demographic risk factors for ROP in an effort to make a more precise estimate of the association between risk factors and disease onset.

Of the 18 studies researchers included (342,005 infants), 4 investigated United States populations. The rest were conducted in Turkey, Argentina, Australia, Austria, Costa Rica, India, Iran, Italy, The Netherlands, Sweden, Switzerland, South Korea, or Taiwan.

The studies had low overall risk of bias, researchers report. Five studies collected data from at least 75% of their region’s eligible participants. Nine did not report the portion of population screened. GRADE certainty of evidence was moderate.

The researchers discovered that screening threshold ranged from at most 27 weeks GA to at most 34 weeks GA and from at most 750 g BW to at most 1750 g BW. Five guidelines recommended screening up to 32 weeks GA (inclusive) or 1500 g BW.

After pooling data, the researchers explain that overall risk of ROP among 155,472 preterm infants was 18.8% (10.8% to 32.2%). Thirteen studies found that 20.5% of ROP cases were severe ROP (stage of at least 3 in 1 eye). ROP treatment was performed in 14.8% of all cases.

This indicates that infants born at 23 weeks GA have an approximate 66.5% risk of developing ROP, with severe risk being 40.3%, and risk of requiring treatment 39.4%.

Per week decrease in GA, the median adjusted odds (aOR) is 1.4 times higher for developing ROP, the research shows.

Five studies found that lower BW was associated with higher risk of ROP. Pooling 2 studies, the researchers found a median 1.8 increase in odds of developing ROP per 100 g decrease in BW.

Regions with higher neonatal mortality have a higher mean GA of infants with ROP compared with studies from geographic region 1.

Three studies indicate that neonatal sepsis and bronchopulmonary dysplasia (BPD)/chronic lung disease (CLD) double the risk of ROP (range 1.423-2.85, 1.70-13.203 respectively).

Higher numbers of blood transfusions raise the risk of ROP, 2 studies show. Pre-eclampsia lowers the risk of ROP in infants with very low birth weight (VLBW).

Limitations of the study included variation in studies’ entry criteria, time period, and methodology. Nonrandomized studies may have involved confounding bias.

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.


Yu CW, Popovic MM, Dhoot AS, et al. Demographic risk factors of retinopathy ofprematurity: A systematic review of population-based studies. Neonatol. Published online February 4, 2022. doi:10.1159/000519635