Inclusion Criteria:  Immediate postpartum mothers of newborns with a term of < 33 weeks (32 weeks + 6 days) primiparous mothers Mothers with vaginal delivery, without oxytocin infusion after delivery Mothers planning to breastfeed, with no maternal contraindication to breastfeeding  Exclusion Criteria:  Substance abuse: active smoking at the time of delivery, alcohol, drugs Use of medication: antidepressants or psychotropic drugs or centrally acting anti-emetics Active depression or history of depression (under medical care with medical follow-up) in the year preceding the birth, on questioning Chromosomal abnormality or congenital malformation of pre- or post-natal diagnosis in the newborn Language barrier not allowing proper explanation of the protocol and responses to questionnaires