OBJECTIVE:
Fetal dysregulation of T helper cell pathways may predispose to allergy, as high cord blood T helper 2/T helper 1 ratios have been shown to precede development of allergic diseases. We aimed to determine whether prenatal eicosapentaenoic acid and docosahexaenoic acid supplementation reduces T helper 2 to T helper 1-associated chemokine ratios. We also explored the effect of mode of delivery on T helper 2/T helper 1 ratios.

STUDY DESIGN:
We conducted a secondary analysis of a randomized placebo controlled trial initially performed to assess the effects of docosahexaenoic acid or eicosapentaenoic acid supplementation on pregnancy-related depressive symptoms among 126 participants. Cord plasma specimens from 98 newborns were assayed for chemokines associated with T helper 2 (thymus and activation-regulated chemokine [CCL17], macrophage-derived chemokine [CCL22], eotaxin [CCL 11]) and T helper 1 (interferon-inducible protein-10 [CXCL 10]) by enzyme-linked immunosorbent assay and Multiplex immunoassays. Ratios of log-transformed chemokines macrophage-derived chemokine/interferon-inducible protein-10 and thymus and activation-regulated chemokine/interferon-inducible protein-10 were compared between groups by analyses of variance. Multiple linear regression was performed to examine associations between treatments and chemokine ratios, adjusting for covariates.

RESULTS:
After adjusting for gestational age at delivery, birthweight, and mode of delivery, both omega-3 supplementation groups were associated with lower macrophage-derived chemokine/interferon-inducible protein-10 ratios than placebo (eicosapentaenoic acid: coefficient -1.8; 95% confidence interval [CI], -3.6 to -0.05; P = .04; docosahexaenoic acid: -2.0; 95% CI, -3.9 to -0.07; P = .04). Similar associations were found for thymus and activation-regulated chemokine/interferon-inducible protein-10 (eicosapentaenoic acid: -1.5; 95% CI, -3.0 to 0.06; P = .06; docosahexaenoic acid -2.2; 95% CI, -3.8 to -0.52; P = .01). Cesarean delivery was associated with higher macrophage-derived chemokine/interferon-inducible protein-10 (1.6; 95% CI, 0.01-3.3; P = .049) and thymus and activation-regulated chemokine/interferon-inducible protein-10 (1.5; 95% CI, 0.1-2.9; P = .042) ratios than vaginal delivery.

CONCLUSION:
Prenatal supplementation with eicosapentaenoic acid and docosahexaenoic acid resulted in decreased cord blood T helper 2/T helper 1 chemokine ratios. Cesarean delivery was associated with a pronounced T helper 2 deviation at birth.