Coregulation of Diurnal Cortisol in Mexican Origin Mother-Infant Dyads

• In Event: Risk and Protective Factors in the Regulation of Maternal and Infant Cortisol

Abstract

Introduction: Early caregiving experiences shape the developing child’s cortisol levels and trajectories across the day. Mother-infant cortisol attunement is thought to be a physiological manifestation of shared emotional and behavioral experiences (e.g., Feldman, 2007; Hibel et al., 2014) and to provide external regulation for the infant’s developing regulatory abilities. Maternal cortisol reliably attunes with child cortisol at multiple time points across the day (Hibel et al., 2014; Papp et al., 2009) and across childhood (Hibel et al., 2015).

Hypotheses: Though Latinx children make up almost a quarter of all births in the U.S. (Martin, 2015), and the majority (63%) of U.S. Latinxs are of Mexican origin (U.S. Census Bureau, 2016), this population is largely understudied. We hypothesize that Mexican origin mother-infant dyads will also exhibit coregulation of diurnal cortisol across the day.

Methods: 62 mother-infant dyads of Mexican origin were recruited when the infant was 6 months (n = 35) or 18 months old (n = 27). During an initial home visit, a two-week collection schedule unique to the individual family’s routine was created so that all mothers were collecting data at waking, evening, and bedtime for three consecutive days per week. During week one, mothers responded to a modified Positive and Negative Affect Scale assessing experiences in the last 30 minutes, yielding a measure of positivity (happy, satisfied, and close and connected to their child).
Results: A series of dual intercept actor partner interdependence models were estimated. Covariates included waketime, compliance, medication use, and infant age. Diurnal decline for infant and mom were modeled by estimating a growth curve model. Mothers and infants exhibited a decline in their cortisol levels across the day (Figure 1). Partner cortisol coefficients were added as interaction terms to model the effect of a partner’s changes in cortisol on the other member, referred to as mom to infant influence and infant to mom influence (Table 1). Mothers’ changes in cortisol across the day were significantly related to similar directional changes in infants’ cortisol levels across the day, and infant changes in cortisol were associated with similar changes in maternal cortisol, while controlling for diurnal decline. In exploratory analyses due to a modest sample size (larger N in process), maternal positivity was examined as a level-2 moderator of cortisol transmission across the day. Greater maternal positivity was associated with stronger mother to infant cortisol transmission from waking to evening (b = .04, p <.01) and evening to bedtime (b = .04, p <.01), as well as infant to mother transmission from evening to bedtime (b = .03, p <.05).
Discussion: The current findings documented cortisol attunement across the day in Mexican origin mother-infant dyads, building on the growing literature on physiological synchrony. Given the importance of cortisol attunement for child development and the parent-child relationship, the present analyses serve as a first step to better understand cortisol attunement in a Latinx sample. The current findings also highlight the importance of further examining maternal positivity in larger samples and exploring how it may shape coregulatory processes.

Authors

• Evelyn Mercado, University of Massachusetts Amherst
  Presenting Author

• Elisa Ugarte, University of California - Davis
  Non-Presenting Author

• Leah Corinne Hibel, University of California - Davis
  Non-Presenting Author