Effect of birth weight on retinopathy of prematurity in discordant twin pairs

Risk Factors for Retinopathy of Prematurity in Preterm Infants in Kerman, Iran

Purpose

Retinopathy of prematurity (ROP) is the main cause of blindness in premature infants. Despite developments in neonatal care and management guidelines, ROP is becoming increasingly prevalent worldwide. Hence, the identification of risk factors for ROP is critical to diminish the burden of the disease.

Methods

This cross-sectional study included all infants with gestational age ≤ 36 weeks referred to the ophthalmology clinic at Shafa hospital, Kerman, Iran from 2014 to 2015. Ophthalmologic examinations were performed followed by demographic and ophthalmic data collection and analysis.

Results

A total of 579 preterm neonates were screened including 325 boys and 254 girls. The incidence of ROP was 17.96%. Mean birth weight (BW) and gestational age (GA) were 1668.0 grams and 31.2 weeks, respectively. The results indicated that BW, GA, duration of hospitalization and oxygen therapy were significantly related to the development of ROP, however, after multivariate logistic regression analysis, only BW and duration of hospitalization remained significant. There were no significant associations between gender, type of delivery, or assisted reproductive technologies, and ROP (P = 0.461, 0.461, and 0.826, respectively).

Conclusion

BW and duration of hospitalization were significant risk factors for ROP in the current study. BW was also strongly associated with the need for therapy.

Association between fetal growth-restriction and retinopathy of prematurity using a unique identical twin model

BACKGROUND

Research in singletons identified fetal growth restriction (FGR) as a risk factor for retinopathy of prematurity (ROP), but is generally subject to confounding by genetic, obstetric, and maternal factors. We investigated the effect of FGR on ROP in growth-discordant identical twins, thereby controlling for confounding factors.

METHODS

All data of monochorionic (MC) twin pairs with a birth weight discordance ≥20% born in our center between 2010 and 2021 were retrospectively reviewed for the presence of ROP. Potential risk factors for ROP were analyzed. Outcomes were compared between the smaller and larger twin.

RESULTS

We included 88 MC twin pairs with growth discordance. In 34% (30/88), both neonates were at risk of ROP. Prevalence of ROP was higher among the smaller twin compared to the larger twin, 30% (9/30) versus 13% (4/30), respectively (OR 2.8, 95% CI: 1.2-6.6). The smaller twin had a longer duration of mechanical ventilation (8 (1-20) versus 2 (1-4) days) and received their first red blood cell transfusion at an earlier postmenstrual age (29.6 (28.1-31.6) versus 30.4 (29.7-32.6) weeks).

CONCLUSIONS

In this identical twin model, FGR is associated with almost tripled odds of ROP development, suggesting that both unfavorable antenatal growth conditions and adverse neonatal outcomes affect postnatal retinal vascular proliferation.

IMPACT

Fetal growth restriction in growth-discordant identical twins is associated with almost tripled odds of developing retinopathy of prematurity in the smaller twin. Since these twins do not only differ in birth weight but also duration of mechanical ventilation and timing of the first red blood cell transfusion, both unfavorable antenatal growth conditions and adverse neonatal outcomes can affect postnatal retinal vascular proliferation. More attention for preventing retinopathy of prematurity is needed in those with fetal growth restriction who received prolonged duration of mechanical ventilation, oxygen supplementation, or a first red blood cell transfusion <32 weeks postmenstrual age.

A Review on the Incidence and Related Risk Factors of Retinopathy of Prematurity Across Various Countries

Retinopathy of prematurity (ROP) is an ophthalmologic condition that is one of the leading causes of preventable childhood blindness. Due to the premature nature of blood vessels in preterm infants, retinal vessels are prone to damage. The incidence of ROP ranges with great variation across countries, and this study aims to identify the incidence and its related risk factors. A compilation of studies investigating the incidence of ROP was acquired through the PubMed and Google Scholar databases with a full free text in English filter set. All members of the study were involved in designating studies based on continent and arranging them into a table format. Following this, reasons for the variation in the incidence of ROP were investigated by individually assessing each study. The variation of an increased incidence of ROP seen in low-income countries (LICs) was most likely due to the availability of resources. As a preterm birth can give rise to further complications such as the development of sepsis, it is important to manage preterm birth with the utmost caution. Evidence has suggested that the two key variables in reducing the morbidity and mortality of ROP are the implementation of a screening and treatment protocol with controlled use of oxygen and the availability of resources in hospitals to adequately identify and manage ROP as early as possible. Through a comprehensive overview of the incidence of ROP, it is vital to review screening and treatment protocols in each hospital for ROP, which would aid in preventing its occurrence and initiating early treatment.