Sex-Specific Associations Between Early-Life Unpredictability and Trajectories of Body Mass Index From Infancy to Adolescence.

OBJECTIVE: Unpredictability in early life is an understudied aspect of early life adversity that provides important signals to the child about their environment. Recent work shows the predictability of patterns of parental signals on a moment-to-moment timescale sculpts the developing brain during sensitive windows, offering a potential pathway through which early life experiences shape child development. Both experimental non-human animal models and observational human research show sex-specific links between early life exposure to unpredictable patterns of parental sensory signals and aberrant offspring development. The impact of predictability of sensory signals on physical health outcomes, such as BMI, remains unknown. Here, we examined the sex-specific association between unpredictable maternal sensory signals during infancy and child BMI trajectories from infancy through adolescence.

METHODS: In a prospective cohort ( N =190 mother/child dyads), we quantified the unpredictability of maternal sensory signals (unpredictability of transitions between visual, auditory, and tactile signals mothers provide their infant) from free-play interactions at 6 and 12 month of age. Child BMI was measured longitudinally 7 times from infancy through adolescence. General linear mixed models assessed relations of unpredictability with BMI trajectories.

RESULTS: Greater unpredictability of maternal sensory signals in infancy was associated with higher BMI over time for females (b=0.07, SE=0.03, P =.047 for overall trajectory difference), but not males (b=-0.03, SE=0.04, P =.450 for overall trajectory difference).

CONCLUSIONS: Findings suggest early life unpredictability may be an important signal shaping biobehavioral pathways to later child weight status among females.