To evaluate the impact of low birth weight as a risk factor for retinopathy of prematurity (ROP) that will require treatment in correlation with gestational age at birth (GA). In total, 2941 infants born <32 weeks GA were eligible from five cohorts of preterm infants previously collected for analysis in WINROP (Weight IGF-I Neonatal ROP) from the following locations: Sweden (EXPRESS) (n = 426), North America (n = 1772), Boston (n = 338), Lund (n = 52), and Gothenburg (n = 353). Data regarding GA at birth, birth weight (BW), gender, and need for ROP treatment were retrieved. Birth weight standard deviation scores (BWSDS) were calculated with Swedish as well as Canadian reference models. Small for gestational age (SGA) was defined as BWSDS less than −2.0 SDS using the Swedish reference and as BW below the 10^th percentile using the Canadian reference charts. Univariate analysis showed that low GA (p<0.001), low BW (p<0.001), male gender (p<0.05), low BWSDS_Canada (p<0.001), and SGA_Canada (p<0.01) were risk factors for ROP that will require treatment. In multivariable logistic regression analysis, low GA (p<0.0001), male gender (p<0.01 and p<0.05), and an interaction term of BWSDS*GA group (p<0.001), regardless of reference chart, were risk factors. Low BWSDS was less important as a risk factor in infants born at GA <26 weeks compared with infants born at GA ≥26 weeks calculated with both reference charts (BWSDS_Sweden, OR = 0.80 vs 0.56; and BWSDS_Canada, OR = 0.72 vs 0.41). Low BWSDS as a risk factor for vision-threatening ROP is dependent on the infant's degree of immaturity. In more mature infants (GA ≥26 weeks), low BWSDS becomes a major risk factor for developing ROP that will require treatment. These results persist even when calculating BW deficit with different well-established approaches.

Background: The most severe form of rapidly progressing retinopathy of prematurity (ROP) is termed aggressive posterior ROP (APROP). APROP frequently causes severe visual impairment in affected preterm infants despite timely and appropriate laser treatment. Objectives: We investigated the postnatal characteristics associated with APROP development in a national Swedish cohort. Methods: This retrospective, 1:1 matched case-control study included all infants that developed APROP in zone 1 (n = 9) between 2008 and 2012. Control infants, matched for gestational age and birth weight, developed ROP no worse than stage 2 (n = 9). We retrieved data from medical records on infant birth characteristics, postnatal morbidities, and blood analyses from birth to the first ROP treatment. Infectious episodes included sepsis, C-reactive protein ≥10 mg/l, and other clinical signs of infection that required antibiotic treatment. A platelet count <100 × 10⁹/l was considered to be thrombocytopenia. Results: All APROP cases postnatally developed at least two infectious episodes, one in the first month and one around the time of ROP diagnosis. All APROP cases exhibited thrombocytopenia in the first month, and 6/9 exhibited thrombocytopenia around the time of ROP diagnosis. Compared to the controls, APROP cases more frequently developed necrotizing enterocolitis (8/9 vs. 1/9; p < 0.01) and sepsis (9/9 vs. 3/9; p < 0.01), and they had significantly lower median platelet counts (90 × 10⁹/l, range 4-459, vs. 158 × 10⁹/l, range 20-500; p < 0.001). Conclusion: Multiple infectious episodes and thrombocytopenia, particularly around the time of ROP diagnosis, were associated with APROP development.

Retinopathy of prematurity (ROP) is characterized by abnormal retinal neovascularization in response to vessel loss. Platelets regulate angiogenesis and may influence ROP progression. In preterm infants, we assessed ROP and correlated with longitudinal postnatal platelet counts ( n = 202). Any episode of thrombocytopenia (<100 × 10 ⁹ /l) at ≥30 weeks postmenstrual age (at onset of ROP) was independently associated with severe ROP, requiring treatment. Infants with severe ROP also had a lower weekly median platelet count compared with infants with less severe ROP. In a mouse oxygen-induced retinopathy model of ROP, platelet counts were lower at P17 (peak neovascularization) versus controls. Platelet transfusions at P15 and P16 suppressed neovascularization, and platelet depletion increased neovascularization. Platelet transfusion decreased retinal of vascular endothelial growth factor A (VEGFA) mRNA and protein expression; platelet depletion increased retinal VEGFA mRNA and protein expression. Resting platelets with intact granules reduced neovascularization, while thrombin-activated degranulated platelets did not. These data suggest that platelet releasate has a local antiangiogenic effect on endothelial cells to exert a downstream suppression of VEGFA in neural retina. Low platelet counts during the neovascularization phase in ROP is significantly associated with the development of severe ROP in preterm infants. In a murine model of retinopathy, platelet transfusion during the period of neovascularization suppressed retinopathy.

To evaluate the ability of a postnatal weight-gain algorithm (WINROP) to identify sight-threatening retinopathy of prematurity (ROP type 1) in a nation-based extremely preterm infant cohort. This study enrolled all 707 live-born extremely preterm (gestational age [GA] <27 weeks) infants, born 2004–2007 in Sweden; the Extremely preterm Infants in Sweden Study (EXPRESS). WINROP analysis was performed retrospectively in 407 of the infants using weekly weight gain to assess the preterm infant’s risk of developing ROP type 1 requiring treatment. GA, birthweight (BW), and weekly postnatal weight measurements were entered into WINROP. WINROP signals with an alarm to indicate if the preterm infant is at risk for ROP type 1. In this extremely preterm population, WINROP correctly identified 96% (45/47) of the infants who required treatment for ROP type 1. The median time from alarm to treatment was 9 weeks (range, 4–20 weeks). WINROP, an online surveillance system using weekly weight gain, identified extremely preterm infants at risk for ROP type 1 requiring treatment at an early stage and with high sensitivity in a Swedish nation-based cohort.

Aim: This study evaluated the correlation between retinopathy of prematurity (ROP), anaemia and blood transfusions in extremely preterm infants.Methods: We included 227 infants born below 28 weeks of gestation at King Edward Memorial Hospital, Perth, Australia, from 2014–2016. Birth characteristics and risk factors for ROP were retrieved, and anaemia and severe anaemia were defined as a haemoglobins of <110 g/L and <80 g/L, respectively. Logistic regression was used for the analysis.Results: Retinopathy of prematurity treatment was needed in 11% of cases and the mean number of blood transfusions (p < 0.01), and mean number of weeks of anaemia (p < 0.001) and of severe anaemia (p < 0.05), had positive associations with ROP cases warranting treatment. In the multivariate logistic regression analysis, the best‐fit model of risk factors included anaemic days during first week of life, with an odds ratio (OR) of 1.46% and 95% confidence interval (CI) of 1.16–1.83 (p < 0.05), sepsis during the first 4 weeks of life (OR 3.14, 95% CI 1.10–9.00, p < 0.05) and days of ventilation (OR 1.03, 95% CI 1.01–1.06, p < 0.05).Conclusion: The duration of anaemia during the first week of life was an independent risk factor for ROP warranting treatment and preventing early anaemia may decrease this risk.

Aim: This study investigated childhood diagnoses in children born extremely preterm before 24 weeks of gestation.Methods: Diagnoses of neurodevelopmental disorders and selected somatic diagnoses were retrospectively retrieved from national Swedish registries for children born before 24 weeks from 2007 to 2018. Their individual medical files were also examined.Results: We studied 383 children born at a median of 23.3 (range 21.9–23.9) weeks, with a median birthweight of 565 (range 340–874) grams. Three‐quarters (75%) had neurodevelopmental disorders, including speech disorders (52%), intellectual disabilities (40%), attention deficit hyperactivity disorder (30%), autism spectrum disorders (24%), visual impairment (22%), cerebral palsy (17%), epilepsy (10%) and hearing impairment (5%). More boys than girls born at 23 weeks had intellectual disabilities (45% vs. 27%, p < 0.01) and visual impairment (25% vs. 14%, p < 0.01). Just over half of the cohort (55%) received habilitation care. The majority (88%) had somatic diagnoses, including asthma (63%) and failure to thrive/short stature (39%).Conclusion: Most children born before 24 weeks had neurodevelopmental disorders and/or additional somatic diagnoses in childhood and were referred to habilitation services. Clinicians should be aware of the multiple health and developmental problems affecting these children. Resources are needed to identify their long‐term support needs at an early stage.