Fetal dysregulation of T helper (Th) cell pathways may predispose to allergy, as high cord blood Th2/Th1 ratios have been shown to precede development of allergic diseases. We aimed to determine whether prenatal eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) supplementation reduces Th2 to Th1-associated chemokine ratios. We also explored the effect of mode of delivery on Th2/Th1 ratios.
We conducted a secondary analysis of a randomized placebo controlled trial initially performed to assess the effects of DHA or EPA supplementation on pregnancy-related depressive symptoms among 126 participants. Cord plasma specimens from 98 newborns were assayed for chemokines associated with Th2 [TARC (CCL17), MDC (CCL22), Eotaxin (CCL 11)] and Th1 [IP10 (CXCL 10)] by ELISA and Multiplex immunoassays. Ratios of log-transformed chemokines MDC/IP10 and TARC/IP10 were compared between groups by ANOVA. Multiple linear regression was performed to examine associations between treatments and chemokine ratios, adjusting for covariates.
After adjusting for gestational age at delivery, birth weight and mode of delivery, both omega-3 supplementation groups were associated with lower MDC/IP10 ratios than placebo [EPA: coefficient −1.8 (95% CI −3.6, −0.05), p=0.04; DHA: −2.0 (95% CI −3.9, −0.07), p=0.04]. Similar associations were found for TARC/IP10 [EPA: −1.5 (95% CI −3.0 0.06), p=0.06; DHA −2.2 (95% CI −3.8,−0.52), p=0.01]. Cesarean delivery was associated with higher MDC/IP10 [1.6 (95% CI 0.01, 3.3), p=0.049] and TARC/IP10 [1.5, (95%CI 0.1, 2.9), p=0.042] ratios than vaginal delivery.
Prenatal supplementation with EPA and DHA resulted in decreased cord blood Th2/Th1 chemokine ratios. Cesarean delivery was associated with a pronounced Th2 deviation at birth.