Fetal sex is associated with maternal stimulated cytokine production, but not serum cytokine levels, in human pregnancy

Highlights • Data examining associations between fetal sex and maternal immune function are lacking. • Women with female vs male fetuses had greater LPS-stimulated cytokine production. • Effects were seen in each trimester for IL-6, select timepoints for TNF-α and IL-1β. • These findings have implications for maternal health (e.g., asthma) during pregnancy. • Studies of maternal immune function should consider fetal sex, statistically and conceptually.