IntroductionThe prevalence of postnatal depression (PND) is significant: reaching up to 20% in the general population. In mechanistic terms, the risk of PND lies in an interaction between a maternal psychophysiological vulnerability and a chronic environmental context of stress. On the one hand, repetition of stressor during pregnancy mimics a chronic stress model that is relevant to the study of the allostatic load and the adaptive mechanisms. On the other hand, vulnerability factors reflect a psychological profile mirroring mindfulness functioning (psychological quality that involves bringing one’s complete and non-judgemental attention to the present experience on a moment-to-moment basis). This psychological resource is linked to protective and resilient psychic functioning. Thus, PND appears to be a relevant model for studying the mechanisms of chronic stress and vulnerability to psychopathologies.In this article, we present the protocol of an ongoing study (started in May 2017).Methods and analysisThe study is being carried out in five maternities and will involve 260 women. We aim to determine the predictive psychobiological factors for PND emergence and to provide a better insight into the mechanisms involved in chronic stress during pregnancy. We use a multidisciplinary approach that encompasses psychological resources and biophysiological and genetic profiles in order to detect relevant vulnerability biomarkers for chronic stress and the development of PND. To do so, each woman will be involved in the study from her first trimester of pregnancy until 12 months postdelivery.Ethics and disseminationEthics approval was obtained from the Ile de France III Ethics Committee, France (2016-A00887-44). We aim to disseminate the findings through international conferences and international peer-reviewed journals.Trial registration numberNCT03088319; Pre-results.

(1) Background: the prevalence of postnatal depression (PND) reaches up to 20%. PND could be based on the interaction between a psychological vulnerability and chronic stress that pregnancy would activate. Vulnerability factors reflect a psychological profile mirroring mindfulness-trait (MT). A high level of MT is associated with an efficient regulation of both physiological and psychological stress, especially negative moods. Interestingly, mindfulness level can be improved by program based on mindfulness meditation. We hypothesize that MT is a protective factor for PND. We also postulate that negative moods increase during the pregnancy for women who develop a PND after delivery (2) Methods: we conducted a multicentric prospective longitudinal study including 85 women during their first trimester of their pregnancy and 72 from the childbirth to the baby’s first birthday”. At the inclusion, presence and acceptance of MT and various variables of personality and of psychological functioning were assessed. Mood evolution was monitored each month during the pregnancy and a delivery trauma risk was evaluated after delivery. PND detection was carried out at 48 h, 2, 6 and 12 months after the delivery with the Edinburgh Postnatal Depression Scale with a screening cut-off >11. (3) Results: high-acceptance MT is a protective factor for PND (OR: 0.79). Women without PND displayed less negative mood during pregnancy (p < 0.05 for Anxiety, Confusion and Anger). (4) Conclusions: these results suggest the value of deploying programs to enhance the level of mindfulness, especially in its acceptance dimension, before, during and after pregnancy, to reduce the risk of PND.