Pigs were exposed to heat stress (HS) and thermoneutral (TN) conditions in-utero. Post-weaning, they were exposed to acute heat-stress for a 24-hour period, and differences in physiological response between in-utero treatment groups were determined. Our results indicated that in-utero heat-stress had no effect on core body temperature; however the HS group had a larger cumulative difference (~50%) between rectal and skin temperatures compared to TN pigs. Preliminary, this provides evidence suggesting pigs exposed to in-utero HS may have an altered tolerance to post-natal HS.