Effect of Early Limited Formula on Breastfeeding Duration in the First Year of Life: A Randomized Clinical Trial.

Importance: Breastfeeding through 6 and 12 months are 2 goals of the Centers for Disease Control and Prevention Healthy People 2020 initiative, but the 6-month goal is met for only 52% of US infants and the 12-month goal for 30% of US infants. Objective: To determine whether structured, short-term formula supplementation for at-risk neonates affects the proportion still breastfeeding at 6 and 12 months. Design, Setting, and Participants: This randomized clinical trial conducted at 2 US academic medical centers enrolled 164 exclusively breastfeeding mother-infant dyads of mothers who were not yet producing copious milk and infants who were 24 to 72 hours old with newborn weight loss at or above the 75th percentile for age. Participants were enrolled from January 2015 through September 2016. Interventions: Early Limited Formula (ELF), a structured formula supplementation protocol (10 mL formula fed after each breastfeeding until mothers produced copious milk), compared with control dyads, who continued exclusive breastfeeding and received a safety teaching intervention. Main Outcomes and Measures: The study's primary outcome was any breastfeeding at 6 months. Secondary outcomes included age at breastfeeding cessation and any breastfeeding at 12 months. All outcomes were assessed by maternal phone survey. Results: Eighty-two newborns were randomized to ELF and 82 to the control group. Mean (SD) maternal age was 31.4 (5.9) years, and 114 (69.5%) self-identified as non-Hispanic white; 20 (12.2%), Hispanic; 17 (10.4%), Asian; 5 (3.0%), non-Hispanic black; and 7 (4.3%), other. Compared with controls, mothers randomized to ELF were less likely to be married (n = 53 [64.6%] vs n = 66 [80.5%]; P = .03) and had shorter mean (SD) intended duration of breastfeeding (8.6 [3.4] vs 9.9 [4.4] months; P = .049). Median (interquartile range) duration of breastfeeding in the cohort was 9 (6-12) months. At 6 months, 47 (65%) infants randomized to ELF were breastfeeding, compared with 60 (77%) of the control infants (absolute difference, -12%; 95% CI, -26% to 3%; P = .12). At 12 months, 21 of the 71 ELF infants available for analysis (29.6%) were breastfeeding, compared with 37 of the available 77 (48.1%) control infants (risk difference, -18%; 95% CI, -34% to -3%). Marital status and intended breastfeeding duration were both associated with breastfeeding duration; models adjusting for these found a hazard ratio for time-to-event of breastfeeding cessation through 12 months of 0.74 (95% CI, 0.48-1.14) for ELF infants compared with infants in the control group. Conclusions and Relevance: In this cohort with high breastfeeding prevalence, ELF was not associated with any improvement in breastfeeding duration. Future research should examine the effect of ELF in populations at higher risk of early cessation. Trial Registration: ClinicalTrials.gov identifier: NCT02313181.