Abstract
IMPORTANCE: More than one-half of infants younger than 6 months worldwide are partially or exclusively bottle fed. Compared with teat-vented bottles, bottom-vented bottles may reduce air ingestion during feeding, thereby mitigating gastrointestinal discomfort. OBJECTIVE: To evaluate the effectiveness of bottom-vented bottles vs teat-vented bottles in improving infant gastrointestinal function. DESIGN, SETTING, AND PARTICIPANTS: This multicenter randomized clinical trial was conducted from September 2024 to January 2025 at 5 maternal and child health care hospitals in China. Infants aged 0 to 90 days were enrolled. INTERVENTIONS: Infants were fed breast milk or formula for 14 days using bottom-vented or teat-vented bottles. MAIN OUTCOMES AND MEASURES: The primary outcome was mild gastrointestinal discomfort (MGD) at week 2, defined as an Infant Gastrointestinal Symptom Questionnaire (IGSQ) score greater than 23 (range, 13-65). Secondary outcomes included MGD at week 1, weight change from baseline to day 14, IGSQ score, colic, and maternal postpartum anxiety or depression at week 2. Post hoc outcomes included flatulence and crying during and/or after feeding. For the primary outcome, mixed-effects log-binomial regression models were used to estimate relative risks (RRs) with 95% CIs. RESULTS: A total of 1055 infants aged 0 to 90 days were enrolled and randomized to bottom-vented (527 infants) or teat-vented (528 infants) groups. Of 1041 infants in the modified intention-to-treat analysis (mean [SD] age, 25.4 [24.9] days; 575 males [55.2%]), 521 infants in the bottom-vented group did not have a significantly lower MGD prevalence at week 2 than the 520 infants in the teat-vented group (185 infants [35.5%] vs 197 infants [37.9%]; RR, 0.94; 95% CI, 0.80-1.10; P = .44). Similar results were observed for MGD prevalence at week 1. A post hoc subgroup analysis showed a significantly lower MGD prevalence with bottom-vented bottles among infants aged 61 to 90 days (15 infants [21.1%] vs 24 infants [47.1%]; RR, 0.45; 95% CI, 0.26-0.77), but not among younger infants (P = .009 for interaction). Furthermore, bottom-vented group had a lower risk of crying during and/or after feeding (168 infants [32.2%] vs 212 infants [40.8%]; RR, 0.79; 95% CI, 0.67-0.92; P = .003). No significant between-group differences were observed for other secondary outcomes. CONCLUSIONS AND RELEVANCE: In this randomized clinical trial of feeding bottles with different venting methods, bottom-vented compared with teat-vented bottles did not result in a significant reduction in MGD prevalence among infants aged 0 to 90 days. However, a significant reduction was observed among infants aged 61 to 90 days in an exploratory post hoc analysis, which warrants future confirmation. TRIAL REGISTRATION: Chinese Clinical Trial Registry Identifier: ChiCTR2400090082.