Methods: 39 expectant mothers were exposed to a Baby Cry Protocol via an infant simulator, with salivary cortisol collected at five points in time (N = 181). Stepwise, multilevel model creation, via Stata/MP 16.0, resulted in a random intercept and random slope model with an interaction term for total number of ACEs and week of pregnancy. The repeated measures data showed that cortisol levels decreased across collection times, from arrival at the lab, through the Baby Cry Protocol, to recovery.
Results: The final, full model was a random intercept and random slope model that showed an average cortisol values decreased from S1 to S5 (B = -0.001) with a standard deviation among participants of 0.002. Maternal age was negatively associated with cortisol values so that each additional year was associated with a 2.66% decrease in the baseline cortisol level. SES ladder was also negatively associated with cortisol, with a one unit increase in the SES ladder score associated with a 10.28% decrease in the baseline cortisol level. While baseline cortisol levels of African Americans did not statistically significantly differ from Caucasians, individuals in the other race/ethnicity group had 40.85% lower baseline cortisol values than those who self-identified as Caucasian. Predictive margins for the interaction term showed that while exposure to a greater number of ACEs was associated with higher cortisol levels early in the third trimester, the expected increase in cortisol late in pregnancy was blunted for expectant mothers who were exposed to a greater number of ACEs.
Conclusion and Implications: The biological stress responses that mothers exhibit in response to a baby cry have important implications for parenting and, ultimately, for the healthy development of their children. In this study, initial cortisol levels were higher for mothers later in pregnancy if they reported zero ACEs or one ACE, but there appears to be a blunting effect late in pregnancy among mothers who reported two or more ACEs. These data suggest that one possible pathway by which maternal cortisol is impacted is via maternal exposure to ACEs. These findings underscore the importance of prevention of ACEs, screening for ACEs as part of prenatal care, and interventions for mothers who have experienced three or more ACEs prior to pregnancy.