Maternal negative affect in pregnancy predicts cytokine levels which in turn predict birth outcomes - A prospective longitudinal study in a low-risk population.

Background: Stress and negative mood in pregnancy have been linked to less favorable birth outcomes, but the mechanisms underlying this effect remain largely unknown. We examined associations between emotions in pregnancy, pro- and anti-inflammatory cytokines (IFN-γ, IL-6, IL-8, IL-10, IL-12, IL-17, MCP-1, MIP-1β, TNF-α) and birth outcomes (gestational age at birth and birth weight) in a low-risk sample.

Methods: At each trimester of pregnancy, participants (N = 74) completed the Positive and Negative Affect Schedule, Perceived Stress Scale, Edinburgh Postnatal Depression Scale, and State-Trait Anxiety Inventory. They provided blood samples in the third trimester. Multivariate regression with a reduction of dimensionality (orthogonal projection to latent structures) was used to assess associations between maternal emotions, cytokine levels, and birth outcomes.

Results: We found significant positive associations between negative mood (depressive symptoms in the second and third trimesters and negative affect in the third trimester) and anti-inflammatory cytokine IL-10 levels, and negative associations between maternal distress in the second and third trimesters and pro-/anti-inflammatory cytokine ratios (IFN-γ/IL-10, TNF-α/IL-10 and IL-6/IL-10). Higher levels of pro-inflammatory cytokines IFN-γ, IL-12, IL-17, and TNF-α were associated with younger gestational age at birth and lower birth weight.

Limitations: We did not control for relevant factors such as social support, health-related behaviors, or cortisol levels.

Conclusions: Negative mood in mid- and late pregnancy may shift cytokine balance toward the anti-inflammatory cytokine dominance. Our results provide further evidence for the negative association between pro-inflammatory cytokines in late pregnancy and gestational age at birth/birth weight, which we observed even in a low-risk population.