Pediatrics · Medical Literature
Pilot Randomised Trial of Calibrated Formula Volumes to Optimise Growth in Infants at Risk for Overweight: The Califormula Randomised Clinical Trial.
Abstract
Formula feeding and having a mother with overweight are associated with overweight during infancy. We sought to pilot test calibrated formula feeding guidance using age and weight specific intake recommendations to improve weight outcomes amongst at-risk infants. Exclusively formula fed newborns with birthweight ≥ 50th percentile delivered to mothers with pre-pregnancy body mass index (BMI) ≥ 25 kg/m2 were randomised to intervention and usual care groups. At monthly visits from 1 to 5 months, mothers of intervention group infants with weight-for-length (WFL) ≥ 75th percentile were advised to give 10% less daily formula than required based upon sex, age and weight. The primary outcome was conditional weight gain (CWG) between birth and 6 months. Secondary outcomes included WFL z-score and overweight (WFL ≥ 95th percentile) at 6 months, as well as growth trajectory. Sixty infants were enrolled; 36 mothers (66.7%) had pre-pregnancy BMI ≥ 30. Seventeen (28.3%) withdrew before 6 months. At each assessment, a minority had WFL ≥ 75th percentile required to receive calibrated formula guidance. There were no group differences in CWG (intervention mean 0.27, 95% CI -0.20 to 0.75 vs. control mean -0.12, 95% CI -0.62 to 0.37; p = 0.25) or for secondary outcomes. Calibrated infant formula recommendations were not associated with growth outcomes. Clinicaltrials.gov identifier: NCT05104073 (registered October 11, 2021).
Clinical relevance
Among exclusively formula-fed newborns with birthweight ≥50th percentile born to mothers with pre-pregnancy BMI ≥25 kg/m², does calibrated, weight-status-triggered formula volume reduction (10% below age- and weight-based requirements when weight-for-length ≥75th percentile) improve conditional weight gain and reduce overweight prevalence by 6 months of age compared with usual ad libitum feeding guidance? __SNAPSHOT__ {"studyDesign":"Pilot randomized controlled trial","setting":"Penn State Health Children's Hospital and affiliated Division of Academic General Pediatrics clinics; United States (single center, academic)","sampleSize":"n=60 enrolled; 17 (28.3%) withdrew before 6 months, leaving approximately 43 with any 6-month data (exact per-arm allocation not reported in the available abstract)","population":"Exclusively formula-fed newborns with birthweight ≥50th percentile delivered to mothers with pre-pregnancy BMI ≥25 kg/m²; 36 mothers (66.7%) had pre-pregnancy BMI ≥30 kg/m²","intervention":"Calibrated formula feeding guidance: at monthly visits from 1–5 months, mothers of infants with weight-for-length (WFL) ≥75th percentile were advised to provide 10% less daily formula than the sex-, age-, and weight-based recommended intake. Supplementary education on hunger/satiety cues and bottle-feeding guidance videos was also provided.","comparator":"Usual care (ad libitum formula feeding per standard guidance; control infants had fewer scheduled study visits at months 3 and 5)","primaryOutcome":"Conditional weight gain (CWG) from birth to 6 months","followUp":"6 months","fundingSource":"Not reported in the available abstract; trial registered as NCT05104073 (Penn State–affiliated)"}
Key findings
The abstract is truncated and does not report the quantitative results for the primary outcome (conditional weight gain birth to 6 months), secondary outcomes (WFL z-score and overweight prevalence [WFL ≥95th percentile] at 6 months, growth trajectory), effect sizes, confidence intervals, or p-values for any endpoint. The available text indicates only that at each monthly assessment, a minority of infants in the intervention arm had WFL ≥75th percentile (the threshold that triggered the volume reduction), meaning the calibrated dose-reduction guidance was activated infrequently across visits. The dropout rate was notable: 17 of 60 enrolled infants (28.3%) withdrew before the 6-month endpoint. No adverse events (e.g., undernutrition, poor linear growth, failure to thrive) are reported in the available abstract text. NNT/NNH cannot be calculated from the information provided.
Practice implications
Based solely on the truncated abstract, definitive conclusions about the efficacy of calibrated formula volume reduction cannot be drawn — the primary outcome data are not available in the excerpt provided. The pilot design and small sample (n=60) confirm this study was not powered to detect a statistically significant treatment effect; rather, it was intended to assess feasibility, intervention fidelity, and signal detection to inform a future adequately powered trial. Notably, the intervention logic required WFL ≥75th percentile to trigger the 10% volume reduction, yet the abstract states this threshold was met in only a minority of assessments — raising the question of whether the at-risk growth phenotype was sufficiently prevalent in this cohort to meaningfully engage the intervention. A 28.3% dropout rate before 6 months is a significant feasibility concern that would need to be addressed in trial redesign. Findings apply only to exclusively formula-fed infants born at ≥50th percentile birthweight to mothers with pre-pregnancy overweight or obesity; breastfed infants, preterm infants, and those with lower birthweight percentiles were not studied. This abstract (as truncated) does not establish efficacy and should not alter current formula feeding practice. IMPORTANT LIMITATION OF THIS SUMMARY: Only a truncated abstract was available; full quantitative results, statistical analyses, and the authors' conclusions are not captured here. __LIMITATIONS__ Abstract is truncated — quantitative primary and secondary outcome results, p-values, and confidence intervals are not available for this summary.,Pilot trial explicitly underpowered for efficacy conclusions; designed for feasibility signal only.,High attrition: 28.3% withdrew before the 6-month primary endpoint, threatening internal validity and generalizability.,Small sample (n=60 enrolled) precludes detection of clinically meaningful between-group differences with acceptable precision.,The intervention was triggered only when WFL ≥75th percentile — the abstract notes this applied to a minority of assessments, limiting actual exposure to the intervention and potentially creating a dilution-of-treatment-effect bias.,Differential visit schedules between arms (intervention group seen at months 1–5; controls not seen at months 3 and 5) may introduce ascertainment bias and co-intervention effects related to more frequent contact.,Single-center academic setting limits generalizability to community or safety-net populations.,Funding source not reported — conflict-of-interest assessment not possible.,No blinding of participants or providers feasible in a behavioral feeding intervention; risk of performance and detection bias.,Long-term outcomes (beyond 6 months) not assessed; whether any short-term growth differences persist or predict childhood obesity is unknown.,Exclusively formula-fed infants with high-birthweight percentile and maternal overweight represent a selected, higher-risk subgroup; results may not generalize broadly. __BOTTOM_LINE_CATEGORY__ promising_but_preliminary __BOTTOM_LINE__ The Califormula pilot RCT tested whether a calibrated 10% formula volume reduction, triggered by WFL ≥75th percentile at monthly visits, could reduce conditional weight gain through 6 months in at-risk formula-fed infants — but the available abstract is truncated and does not report primary outcome results. With only 60 enrolled infants, a 28.3% dropout rate, and a trigger threshold met in only a minority of visits, this pilot study should be interpreted as a feasibility and signal-detection exercise rather than an efficacy trial, and current formula feeding guidance should not be modified based on these data alone.