Title: Are maternal depression, breastfeeding, maternal alcohol intake and infant biological vulnerability effect modifiers or confounders of the maternal sensitivity and infant cognitive development association?
Description: Background: Maternal sensitivity, or high quality maternal caregiving, in which the mother leads and structures the infant’s early experiences in a responsive way, is associated with improved child development outcomes and health, both in the immediate and long term, and thus an important area of public health research. Although previous research has established that exposure to high maternal sensitivity advances the outcome of infant cognitive development, factors such as breastfeeding, which is hypothesized to confound the association, or depression, which is negatively associated with sensitivity, have not yet been examined together in a single study. Maternal alcohol use, associated with both breastfeeding and depression, has not been examined in any study investigating the sensitivity-cognitive development association. The majority of infant studies examining the maternal sensitivity-infant cognition association include either normal birth weight infants or LBW infant samples. Using the LBW category may result in potential misclassification since this group combines at least two different phenomena and includes infants who have had either compromised gestational time as in the case of small for gestational age (SGA), or insufficient gestational time, as in the case of premature birth, or both.

In studies using comparison groups, normal birth weight infants are sometimes compared to LBW infants or infants born prematurely. However, none of these studies examine the association between sensitivity and cognitive outcome in infants exclusively premature or SGA. Aim: This study investigates the association of several factors: (1) maternal depressive symptomology, (2) breastfeeding, (3) concurrent maternal alcohol intake and (4) infant biological vulnerability upon outcomes of (1) Maternal Sensitivity and (2) Infant Cognitive Development, as well as their effect on the association between senstivity and cognitive development. Methods: Using data from the Early Childhood Longitudinal Study-Birth (ECLS-B) Cohort, a nationally representative sample of U.S. born children, depressive symptomology was evaluated as an effect-modifier, and breastfeeding was evaluated as a confounder of the sensitivity-cognitive development association. Maternal alcohol use and biological vulnerability were also hypothesized to be confounders of the sensitivity-cognitive association.

Univariate and multi-variable regression analyses were used to examine whether the four maternal factors were associated with Maternal Sensitivity, measured by the Nursing Child Assessment Teaching Scale (NCATS), and with Cognitive Development, measured by the Bayley Scale of Infant Development, Research Edition (BSF-R). Results: In univariate analyses, breastfeeding, depressive symptomology and alcohol use were associated with maternal sensitivity but only breastfeeding and depressive symptomology were associated with Cognitive Development In a final model examining the effect of sensitivity, depressive symptomology and breastfeeding upon the outcome of Cognitive Development, sensitivity (β =.375, p<.001) remained significantly associated with cognitive development after adjusting for breastfeeding (β =1.592, p<.001), depressive symptomology (β =-.061), p<.05), demographic factors and birthweight (R2=.053, p<.001). Depressive symptomology was not an effect modifier of the sensitivity-cognitive developmental association.

Univariate regression analyses showed that of the measures of biological vulnerability, premature birth had the greatest association with both sensitivity and cognitive development in comparison to the LBW or SGA. In a multivariate regression model in which maternal sensitivity as an outcome, premature birth (β= -.524***) was associated with maternal sensitivity (R2=.100, p<.001), after adjusting for maternal depression and breastfeeding. In a multivariate regression model analysing the effect premature birth and maternal factors, including sensitivity in which cognitive development was the outcome, maternal sensitivity (β=.369, p<.001) and breastfeeding (β=1.567, p<.001) were positively associated with infant cognitive development, while premature birth (β= -2.949, p<.001) was negatively associated (R2=.049, p<.001). Conclusion: This research demonstrates that an independent association between maternal sensitivity and infant cognitive development remains even after adjusting for breastfeeding, and that breastfeeding is a separate means to advancing infant cognitive development.

Premature birth, rather than SGA drove the negative association between low birth weight and cognitive development. Future research should look at the effects of premature birth separately from SGA when examining developmental outcomes. Keywords: Maternal Sensitivity, Parenting, Cognitive Development, Breastfeeding, Maternal Depression, Premature Birth, Small for Gestational Age, Low Birth Weight.