Participant flow and follow up—We invited 454 women to participate, 176 refused (). Reasons for refusal included: wanting to use dummy (45/164, 27%), not wanting to use dummy (23/164, 14%), wanting to use a bottle (16/164, 10%), study did not appeal (36/164, 22%). Twelve infants died before discharge and four were withdrawn from the study at the mothers' request. Thus, of the 319 infants and 278 mothers enrolled, 303 (95%) and 265 (95%), respectively, were available for the primary analyses (cup/no dummy n = 82, cup/dummy n = 69, bottle/no dummy n = 70, bottle/dummy n = 82).
Recruitment and trial participation
Characteristics of participants—Most maternal and neonatal characteristics were balanced between groups (tables and ). There was, however, a ≥ 10% difference between dummy and no dummy for primiparity and number who had breast fed before and between cup and bottle for primiparity.
Maternal characteristics at trial entry.* Figures are numbers (percentages) unless stated otherwise
Neonatal characteristics at birth.* Figures are numbers (percentages) unless stated otherwise
Compliance—Non-compliance was high (). Of the infants randomised to cup feeding, 56% (85/151) had a bottle introduced, and of the infants randomised to no dummy 31% (47/152) had a dummy introduced. Reasons for introducing a bottle were available for 91% (77/85) of the infants, and reasons for introducing a dummy were available for 81% (38/47). For 44% (34/77) the mother decided to introduce a bottle; in 33% (25/77) the decision was taken on the advice of the nurse/midwife (some mothers said both of these had occurred). Of the 77 mothers, 39% (30) did not like, or had problems with, cup feeding, including the infant not managing cup feeds, spilling a lot, not being satisfied, or taking too long to feed. 12% (9/77) said the staff refused to cup feed their infant. Dummies were introduced because the baby was unsettled (37%, 14/38) and to teach the baby to suck (29%, 11/38). Primiparous, tertiary educated women, whose household income was from full time work from either partner, and who had a singleton infant > 28 weeks' gestation were more likely to have complied with the study protocol.
Breast feeding on discharge home—Not using a dummy had no significant effect on the proportion of infants who were being fully breast fed at discharge (0.84, 0.51 to 1.39, P = 0.50) or partly breast feeding (0.83, 0.45 to 1. 05, P = 0.53) (). Cup feeding significantly increased the odds of full breast feeding at discharge (1.73, 1.04 to 2.88, P = 0.03) (). The number needed to treat (where “treatment” means cup feeding) for one extra infant to be discharged home fully breast feeding was seven (95% CI 4 to 41). Infants randomised to cups were more likely to have any breast feeding, but this was not significant (1.37, 0.78 to 2.38, P = 0.27) (). In total 6/265 (2%) women with 7/303 (2%) infants chose to express breast milk and bottle feed on discharge home.
Comparison of prevalence of breast feeding at discharge, 3 months, and 6 months between groups randomised to dummy and no dummy
Comparison of prevalence of breast feeding at discharge, 3 months, and 6 months between groups randomised to cup and bottle
Breast feeding at three and six months after discharge—There were no significant differences in the prevalence of any breast feeding in infants randomised to no dummy compared with dummy at three (0.99, 0.56 to 1.77, P = 0.98) and six (1.23, 0.66 to 2.30, P = 0.51) months after discharge (). There were minor, non-significant increases in the prevalence of any breast feeding in infants randomised to cup feeds compared with bottle at three (1.31, 0.77 to 2.23, P = 0.33) and six (1.44, 0.81 to 2.57, P = 0.22) months after discharge ().
Length of hospital stay—There was no significant difference (median days, interquartile range) in the length of stay between those randomised to no dummy (53, 35-74) or to dummy (50, 33-78) (hazard ratio 0.98, 0.76 to 1.26, P = 0.87). Discharge from hospital was significantly delayed for those randomised to cup feeds (cup 59, 37-85; bottle 48, 33-65; 0.71, 0.55 to 0.92, P = 0.01). The differences by gestational age remained significant (< 28 weeks: cup 93, 86-113; bottle 93, 72-100; 0.55, 0.32 to 0.94, P = 0.03; 28-< 34 weeks: cup 45, 32-66; bottle 40, 32-55; 0.69, 0.52 to 0.93, P = 0.01).
Adverse events—No adverse events were associated with any of the interventions.