Objective: This study aimed to comprehensively describe inflammatory responses to trivalent influenza virus vaccine (TIV) among pregnant women and determine whether responses differ compared to non-pregnancy.

Methods: Twenty-eight pregnant and 28 non-pregnant women were vaccinated. Serum cytokines were measured at baseline, and 1, 2, and 3 days post-vaccination. Anti-influenza antibody titers were measured at baseline and 1 month post-vaccination.

Results: Overall, following vaccination, tumor necrosis factor (TNF)-α and interleukin(IL)-6 increased significantly, peaking at 1 day post-vaccination (P's < 0.001). Pregnant versus non-pregnant women showed no differences in IL-6, TNF-α, or IL-1β responses. Pregnant women showed no change in IL-8 and increases in migration inhibitory factor (MIF), while non-pregnant showed decreases in both. Pregnancy did not significantly alter antibody responses.

Conclusions: Inflammatory responses to TIV are mild, transient, and generally similar in pregnant and non-pregnant women. Given the variability evidenced, vaccination may provide a useful model for studying individual differences in inflammatory response propensity.