Timing of Complementary Feeding in Preterm Infants and Prevalence of Overweight and Obesity: A Randomized Clinical Trial.

Importance: The appropriate time for initiating complementary feeding in preterm infants is crucial for optimizing growth and preventing long-term health issues, such as overweight. Currently, there are no established guidelines for preterm infants. Objective: To investigate the effect of initiating complementary feeding at corrected age 12 weeks vs 17 weeks on the prevalence of overweight and obesity at corrected age 2 years in preterm infants. Design, Setting, and Participants: This multicenter randomized clinical trial was conducted between May 13, 2016, and April 26, 2021, with follow-up completed in December 2023. Seventeen hospitals in the Netherlands recruited preterm infants born between gestational age (GA) 30 and 36 weeks, supplemented with a reference group of full-term infants. Intervention: Preterm infants were randomized to initiating complementary feeding at corrected age 12 weeks (early group) or 17 weeks (late group). Main Outcomes and Measures: The primary outcome was the prevalence of overweight and obesity at corrected age 2 years measured using logistic mixed models. Secondary outcomes were height, weight, head circumference, body mass index, and z scores at corrected age 1 and 2 years, as well as neurodevelopment, atopic dermatitis score, and health-related quality of life. Results: A total of 255 preterm infants were included and randomly assigned, with 131 (51.4%; median [IQR] GA, 34 weeks 2 days [32 weeks 5 days to 35 weeks 1 day]; 77 male [58.8%]) allocated to the early group and 124 (48.6%; median [IQR] GA, 34 weeks 0 days [32 weeks 6 days to 34 weeks 6 days]; 62 male [50.0%]) allocated to the late group. A total of 159 full-term infants (median [IQR] GA, 40 weeks 0 days [39 week 0 days to 41 weeks 0 days]; 84 female [52.8%]) were included as the reference group. Information on the primary outcome was available for 226 preterm infants (88.6%) and 144 full-term infants (90.6%). At corrected age 2 years, the prevalence of overweight was 6.0% (95% CI, 2.7%-11.5%) in the early group and 5.5% (95% CI, 2.3%-11.1%) in the late group. For obesity, the prevalence was 1.7% (95% CI, 0.3%-5.5%) in the early group and 1.8% (95% CI, 0.3%-5.9%) in the late group. The full-term reference group showed a higher prevalence of overweight (9.0%; 95% CI, 5.1%-14.6%) and obesity (3.5%; 95% CI, 1.3%-7.5%). Conclusions and Relevance: In this randomized clinical trial of preterm infants, initiating complementary feeding between corrected age 12 and 17 weeks did not affect overweight and obesity prevalence at corrected age 2 years. Trial Registration: Onderzoekmetmensen.nl Identifier: NL-OMON53076.