Early self-regulation in context: Multidimensional organization of neonatal non-nutritive sucking and its association with subclinical maternal depressive traits

From the very first days of life, infants' affective regulation unfolds within a dyadic co-regulatory system shaped by caregiver responsivity. In contexts of reduced maternal availability, such as maternal depressive states, infants may be required to compensate for diminished interpersonal regulation by increasingly relying on their internal resources. Neonatal non-nutritive sucking (NNS) represents one of the earliest spontaneously available regulatory behaviors, contributing to physiological and behavioral homeostasis from birth. However, it remains unclear whether its spontaneous organization is associated with early relational vulnerability indexed by maternal depressive symptoms. The present study aimed to characterize the spontaneous organization of NNS in a sample of newborns (N = 42) and to examine whether individual differences in NNS are associated with maternal postnatal depressive subclinical traits measured using the Edinburgh Postnatal Depression Scale (EPDS). Results from an exploratory principal component analysis indicated that neonatal sucking behavior was organized along two functional dimensions, reflecting overall sucking effort and behavioral activation, and the temporal organization of sucking bursts. Importantly, higher maternal depressive traits, though subclinical, were selectively associated with increased sucking effort, with infants of mothers reporting higher depressive traits showing more frequent and intense sucking, while no differences emerged for the organizational dimension. Overall, these findings suggest that individual differences in maternal depressive traits within the subclinical range may be associated with neonatal NNS effort, a precocious compensatory mobilization of regulatory resources, potentially serving both to support autonomous regulation and to elicit maternal engagement.