Fetuses, from reptiles to humans, perceive external conspecific and heterospecific sounds. Fetuses are even able to discriminate between familiar and unfamiliar ones. This prenatal auditory experience is a source of fetal memory. Newborns display thus preferences for maternal voices and music listened during pregnancy. Maternal physiology is also a source of sensory experience for fetuses who react to changes in the emotional state of their mother. The continuity between sensory stimuli and maternal emotional reactions provides therefore opportunity for associative learning in utero but no clear evidence has been presented to date. We tested whether the association between human voice playbacks and positive vs negative emotional experiences in pregnant sows could impact the reaction of piglets to these sounds after birth. One month before birth, thirty sows were exposed daily to alternated positive (soft brushing) and negative (electric prod) manipulations by silent caretakers. Ten sows were exposed to the playback of a given human voice during positive manipulations and to another voice during negative manipulations, and vice versa for ten other sows. Ten control sows received no playback. After birth, piglets’ stress was assessed by counting the number of distress calls during social isolation tests. We found that: 1) From 2 days up to three weeks old, experienced piglets were less stressed than control piglets when familiar voices were broadcast; 2) The appeasing effect of the playback was generalized to unfamiliar human voices; 3) Piglets were more stressed when hearing the voice prenatally associated with negative maternal emotions than when exposed to playbacks of the voice prenatally associated with positive maternal emotions. This study opens a new line of researches on the long term effect of in utero associative learning that goes well beyond pigs, providing a framework for reconsidering the importance of sensory and emotional experiences at fetal stages.