The Intervention Nurses Start Infants Growing on Healthy Trajectories (INSIGHT) Study

Principal Hypotheses: An intervention program designed to provide developmentally appropriate guidance to parents of infants on responsive parenting and healthy lifestyle will prevent rapid weight gain in infancy and overweight at age 3 years. Further, compared with control infants, intervention infants will have lower BMI percentiles at age 3. We also hypothesize that control infants will gain weight more rapidly over time, adjusting for trait-stable and time-varying covariates (e.g., maternal pre-pregnancy BMI, percent of feedings that are breast milk vs. formula, sleep duration, and feeding frequency).

The Intervention Nurses Start Infants Growing on Healthy Trajectories (INSIGHT) Study, will test these hypotheses in a two arm randomized trial where participants in a program to prevent childhood obesity will be compared with those in a child safety control program. Nurses will deliver interventions to first-time parents and their infants in both study groups at four home visits in the first year after birth followed by annual clinical research center visits until age 3. Blood samples for genetic testing on appetite, growth, and temperament will be collected from mother, child, and father. The obesity prevention program focuses on messages of responsive parenting and healthy lifestyle, extending from infancy through age 3 years. The intervention will teach first-time parents to interact with their infants in a way that is prompt, emotionally supportive, contingent, and developmentally appropriate. This information is especially important during the first year after birth as infants make a dramatic dietary transition from the initial exclusive milk diet to one with many foods of the adult diet of their culture. During this transition, as foods are being introduced to children, there are numerous opportunities to address dietary content as well as parent feeding style. In addition to these messages, intervention parents will be given education on growth charts, the meaning of growth chart percentiles, and healthy growth patterns during early life. The intervention program is hypothesized to show efficacy in both breast and formula fed infants as measured by the primary outcome, body mass index (BMI) percentile at age 3 years. Additionally, participants will be followed to collect anthropometric measurements at 4,5,6,10,14,and 17 years of age to provide significant insight into long-term obesity risk.

The proposed research adds two major pieces by enrolling second born siblings and collecting genetic specimens from both siblings and their parents. Specifically, this translational research will a) prospectively evaluate obesity-related parenting similarities and differences as well as weight-related outcomes between first and second-born siblings, b) explore how genetic differences among siblings that are associated with appetite, temperament, and obesity susceptibility affect parent-child interactions, degree of responsive parenting, and weight status, and c) determine whether INSIGHT study intervention carryover effects occur among families participating in the observation-only second-born child evaluation.