ABC Baby Study

The primary goal of this project was to identify domains of infant eating behavior and their trajectories over the first year of life. A convenience sample of 284 mother-infant dyads was recruited and enrolled from communities within a 1-hour driving distance of Ann Arbor, Michigan, via social media; flyers in outpatient pediatric clinics and community settings; and targeted outreach by telephone, email, and mail to pregnant women and mothers of newborn infants receiving care within the University of Michigan health system between October 2015 and February 2019. The planned sample size was based on a priori power calculations anticipating 3-5 eating behavior factors, each with 3 different trajectories, providing 81% power to detect a 10% or more change in the likelihood of exhibiting one of an anticipated 3 trajectory patterns of infant growth; the ultimate sample size of 284 was based on feasibility related to recruitment and retention.

The study included a repeated-measures, within-participant experimental design embedded within a longitudinal observational cohort study. The goal was to examine the development of infant eating behavior longitudinally at ages 0.5, 2, 4, 6, 9 and 12 months based on data collected from questionnaires, eating behavior experiments, and anthropometry via home visits by trained research staff. The study was described to participants as seeking to understand infant eating behavior and interactions between mothers and babies in the first year after birth. Inclusion criteria were gestational age of 37.0 to 42.0 weeks, weight appropriate for gestational age, no significant perinatal or neonatal complications, biological mother was the legal and custodial guardian, and infant’s having had consumed 2 oz or more in 1 feeding from an artificial nipple at least once per week. Exclusion criteria were mother not fluent in English; mother younger than 18 years; infant medical problems or diagnosis affecting current or future eating, growth, or development; or child protective services involvement. Mothers provided written informed consent for themselves and their infants. The study was approved by the University of Michigan institutional review board. To facilitate recruitment, dyads could be enrolled at 1 of 3 age points up to and including age 4 months; data collected at enrollment are referred to as baseline.

Mothers responded to questionnaires on demographics, psychosocial stress, perinatal history, feeding behaviors and practices, sleep, their own eating behaviors, infant temperament, their own and the infant’s diet, and infant eating behaviors. Maternal and infant anthropometry was measured by trained research assistants. Mother-infant dyads participated in protocols designed to measure infant response to sucrose, infant ability to delay gratification, infant response to a challenging feeding, the relative reinforcing value of food, eating in the absence of hunger, capacity for regulation of energy intake in response to more frequent feedings and in response to increased caloric density, and response to novel and familiar foods. Maternal feeding behaviors were also coded from video. Biological samples included infant stool and maternal breastmilk.