Background and Aims Early feeding practices, including early introduction to solid foods and overfeeding, are known risk factors for childhood obesity. This study aimed to assess maternal formula feeding practices and infant formula feeding patterns, factors that are known to potentially contribute to later obesity risk.

Methods This Irish prospective observational study involved the recruitment and follow-up of 450 eligible mother-infant pairs to 6 weeks postpartum. Data related to formula milk consumption patterns, formula type/brand changing, additions of solids to bottle feeds were examined, and available infant 6 week weight measurements recorded.

Results In total, 368 (81.8%) mothers provided any formula milk to their infants at 6 weeks; of these, 14 (3.8%) reported to adding solid foods to their infant’s bottle feeds. Almost 50% of formula feeding mothers (n = 181) reported to changing their infant’s formula type/brand at least once during the first 6 weeks, mainly due to increased hunger and feeding frequency (2–3 hourly) (54.8%). Where 6 week infant weight measurements were available (n = 184), a mean of 205ml (SD 45ml) of formula milk/kilogram body weight/day was consumed by these infants.

Conclusion Several formula feeding practices with potential implications for later obesity risk were identified in this study including premature introduction to solids (≤ 6 weeks) and consumption of excessive formula milk volumes at 6 weeks relative to infant feeding guidelines. Early provision of recommended feeding guidelines including specific advice on age-appropriate milk volumes to parents who formula feed should be considered in obesity prevention programmes.