(958) Maternal anxiety moderates the effect of exogenous oxytocin on the HPA axis

We conducted a double-blind randomized controlled trial of nasal OT embedded within the Mood, Mother, and Infant Study, a longitudinal observational cohort recruited in the 3rd trimester of pregnancy. In the first postpartum year, participants completed periodic assessments, including the Edinburgh Postnatal Depression Scale (EPDS), Spielberger State-Trait Anxiety Inventory (STAI), and Beck Depression Inventory (BDI-II). At about 6 years postpartum, participants were randomized to 24 IU of nasal OT or placebo, followed by the Trier Social Stress Test (TSST), which is comprised of a speech task and a math task. The TSST reliably induces large and consistent HPA responses.  We quantified the extent to which postpartum depression and anxiety symptoms above vs. below the median modified the effect of OT on the lagged association between ACTH and CRT. Mixed effects models were used for repeated measures analysis with α=.05.


Results: Of 222 individuals in the parent study, 105 completed the RCT, and measures of ACTH and lagged CRT were available for 85. COVID interrupted data collection, and there were no significant differences between completers and non-completers. In unstratified analysis, we found that OT vs. placebo did not modify the association between ACTH and lagged CRT (p=0.21). We found an interaction between mean STAI (baseline- 6 months postpartum) and ACTH (p=0.03, Figure 1), and between trait anxiety at 12 months and ACTH (p=0.04). The EPDS-ACTH interaction was not significant (p=0.06). We found no effect modification by BDI-II (p=0.79).

Conclusion: Symptoms of postpartum anxiety, but not depression, were associated with modification of the effect of oxytocin on the HPA axis during a standardized social stressor. These findings suggest that dysregulation of oxytocin effects on the HPA axis may contribute to perinatal anxiety symptoms.