Objective To test whether the design of an anti-vacuum infant feeding bottle (one-way air valve (Bottle A; Philips Avent) versus internal venting system (Bottle B; Dr Browns; requiring less infant effort to obtain milk) affects: (i) milk intake and growth; (ii) infant behaviour.

Methods 63 healthy, exclusively formula-fed full-term infants were randomised to Bottle A or B. The primary outcome was infant weight gain to 4 weeks. Secondary outcomes were (i) length and head circumference gain; (ii) milk intake from 0–2 weeks; (iii) infant behaviour at 2 weeks from a validated 3-day diary recording the time spent asleep, awake & happy, feeding, fussing, crying or with colic; (iv) maternal opinion of bottle.

Results There were no significant differences in infant milk intake or growth between randomised groups. Infants using bottle A had significantly less reported fussing (mean 46 versus 74 minutes/day, p<0.05). Mothers using bottle A awarded significantly better scores for ease of assembly (p = 0.02) and cleaning (p = 0.004). A significantly greater number of mothers using bottle B reported leaking bottles (p = 0.04).

Conclusion Bottle design did not influence early milk intake or growth, suggesting later health effects are unlikely. However, bottle design may have short-term effects on infant behaviour and maternal satisfaction which merit further investigation.

The study was supported by a research donation from Philips Avent.