Maternal environmental enrichment modulates the immune response against an inflammatory challenge during gestation and protects the offspring

•Enrichment of the environment (EE) modulates leukocyte formula in pregnant mice.•EE favors a tolerogenic microenvironment in amniotic fluid in response to LPS.•EE prevents perinatal death and the delay in physical development induced by LPS.•EE is an interesting non-invasive tool transferrable to the human condition.•EE could be used to prevent preterm birth and the sequelae in the offspring.