“…Keenan et al (2002; 2007) based upon the same sample, used the Neonatal Behavioral Assessment Scale (NBAS) (a measure similar to the one used in the present study, but more cumbersome and harder to administer) and a heel stick to stress infants within the first two days of life, but data collected from infants so close to the stressful experience of birth raises the possibility of confounded results (Mears, McAuliffe, Grimes, & Morrison, 2004). Although the majority of studies examined infant basal cortisol, since 2010 a number of other major studies or reviews about infant cortisol reactivity have been published focusing on a variety of variables including preterm infants (Morelius et al, 2016), sex differences in childhood (van der Voorn, Hollanders, Ket, Rotteveel, & Finken, 2017), adverse experiences (Hunter et al, 2011), mother-infant adrenocortical attunement (Hibel et al, 2015), or SES and race/ethnicity in older children (Tackett, Herzhoff, Smack, Reardon, & Adam, 2017).…”