Early life trauma: An exploratory study of effects on OXTR and NR3C1 gene expression and nurturing self-efficacy in mothers of infants.

Background: In animals, adverse early experience alters oxytocinergic and glucocorticoid activity and maternal behavior in adulthood. This preliminary study explored associations among childhood trauma (loss of a parent or sexual abuse in childhood), maternal self-efficacy, and leukocyte gene expression (mRNA) of oxytocin and glucocorticoid receptors (OXTR and NR3C1) in mothers of infants.

Methods: 62 mothers (20 with early life trauma) with healthy 3-month old infants reported maternal self-efficacy, depression, infant temperament, and overall social support; the effects of early trauma on these measures were assessed. Of these, 35 mothers (14 with early trauma) underwent blood draws after 2 infant feeding times; their OXTR and NR3C1 mRNA was compared to a control group of 25 no-infant women without early trauma, and also was examined for associations with self-efficacy.

Results: OXTR mRNA was increased in mothers of infants versus no-infant controls (p < 0.0003), and mothers with greatest prior maternal experience had higher OXTR than those with less experience (0-2 vs. 3+ older children, p < 0.033). Mothers with early trauma and less maternal experience had lower OXTR mRNA than no-trauma mothers (p < 0.029) and lower NR3C1 mRNA than controls (p < 0.004). Mothers with depression also had lower NR3C1 than other mothers (p < 0.003) but did not differ in OXTR. Mothers with early trauma also reported their support network to be less helpful and more upsetting and unpredictable than other mothers (p < 0.035-p < 0.005). Regarding maternal behavior, in mothers with early trauma, helpful support networks increased self-reported nurturing self-efficacy when babies were not fussy but decreased it with fussy babies (p < 0.05). Support was unrelated to self-efficacy in no-trauma mothers. Similarly, among mothers with low OXTR or NR3C1 (-1SD, most having early trauma and lower maternal experience), greater support was associated with lower self-efficacy (p < 0.05), while mothers with high OXTR or NR3C1 (+1SD) tended to have higher self-efficacy with greater support.

Conclusions: These preliminary findings need confirmation in a larger sample but suggest that childhood trauma influences maternal behavior and both OXTR and NR3C1 pathways in mothers of infants, and that both depression and prior maternal experience may be other important factors. Effects on maternal behavior appear to require more complex modeling.