PRL and retinopathy of prematurity: Although vasoinhibin levels (combined with 14‐ and 16‐kDa PRL) significantly increased during the first week after birth in ROP patients, the levels became equal to those in controls during the postnatal weeks, which indicated that dysregulation of the PRL/vasoinhibin axis exerted vasoinhibitory property at early stage and vasoproliferative feature in late phases of the disease.