Purpose: To identify maternal and placental risk factors for the occurrence and progression of retinopathy of prematurity (ROP).
Methods: This was a retrospective cohort study. The study cohort consisted of 246 infants with gestational age ≤ 32 weeks, with histologic examinations of their placentas. Medical records of eligible preterm infants were retrospectively reviewed. A regression model was constructed with control for known or potential factors associated with ROP. Occurrences of ROP, severe ROP (≥ stage 3), and clinically significant ROP requiring laser treatment were assessed.
Results: ROP was diagnosed in 82 of 246 infants (33.3%), including 49 with mild ROP and 33 with severe ROP. Laser treatment was performed on 27 infants (11%: 27/246). Multivariate regression analysis indicated clinical chorioamnionitis and elevated maternal WBC count on admission to be associated with ROP occurrence [odds ratio (OR) = 4.370, P = 0.046; and OR = 1.104 per 1,000 cells/mm(3) incremental increase, P = 0.019, respectively], while the use of tocolytics was associated with reduced occurrence of ROP (OR = 0.278, P = 0.006). Elevated maternal WBC count on admission was also independently associated with ROP progression requiring laser treatment (OR = 1.171 per 1,000 cells/mm(3) incremental increase, P = 0.026). However, neither histologic chorioamnionitis nor funisitis was associated with the occurrence or progression of ROP.
Conclusions: Clinical chorioamnionitis and elevated maternal WBC count, but not histologic chorioamnionitis, were significantly and independently associated with ROP. These findings support the hypothesis that maternal systemic inflammation may play a role in the pathogenesis of ROP.