Objective To evaluate the effects of direct swallowing training (DST) alone and combined with oral sensorimotor stimulation (OSMS) on oral feeding ability in very preterm infants.

Design Blinded, parallel group, randomised controlled trial (1:1:1).

Setting Neonatal intensive care unit of a South Korean tertiary hospital.

Participants Preterm infants born at <32 weeks of gestation who achieved full tube feeding.

Interventions Two sessions per day were provided according to the randomly assigned groups (control: two times per day sham intervention; DST: DST and sham interventions, each once a day; DST+OSMS: DST and OSMS interventions, each once a day).

Primary outcome Time from start to independent oral feeding (IOF).

Results Analyses were conducted in 186 participants based on modified intention-to-treat (63 control; 63 DST; 60 DST+OSMS). The mean time from start to IOF differed significantly between the control, DST and DST+OSMS groups (21.1, 17.2 and 14.8 days, respectively, p=0.02). Compared with non-intervention, DST+OSMS significantly shortened the time from start to IOF (effect size: −0.49; 95% CI: −0.86 to –0.14; p=0.02), whereas DST did not. The proportion of feeding volume taken during the initial 5 min, an index of infants’ actual feeding ability when fatigue is minimal, increased earlier in the DST+OSMS than in the DST.

Conclusions In very preterm infants, DST+OSMS led to the accelerated attainment of IOF compared with non-intervention, whereas DST alone did not. The effect of DST+OSMS on oral feeding ability appeared earlier than that of DST alone.

Trial registration number ClinicalTrials.gov Registry (NCT02508571).