A Cochrane review including 57 studies and 4730 infants showed that oral sucrose at the time of procedure significantly reduced pain scores associated with heel lancing but not ROP screening.
The effects on extremely preterm infants or the long-term effects on any infant of repeated dosing are not known.
Reference: Sucrose as analgesia – Stevens B, Yamada J, Lee GY, Ohlsson A. Sucrose for analgesia in newborn infants undergoing painful procedures. Cochrane Database of Systematic Reviews 2013, Issue 1. Art. No.: CD001069.