17 Newborn altricial mammals need just after birth to locate their mother's nipples for suckling. In 18 this precocious behaviour, including for the human baby, maternal odour via the olfactory process 19 plays a major role. Maternal odour emitted by lactating females or by amniotic fluid (AF) attracts 20 pups, but the chemical identity of this attractant has not yet been elucidated. Here, using 21 behavioural tests and gas chromatography coupled with mass spectrometry (GC-MS) techniques, 22