This will be a very straightforward study assessing changes of immune/inflammatory peripheral biomarkers before/after delivery with postpartum mood and the psychopathological features of postpartum depression (PPD), and with MRI measures of functional and structural brain integrity.

Multimodal assessment of peripheral cytokines, PBMC gene expression, FACS immunophenotyping, and IDO activation, will be validated with (a) clinical data about the presentation of PPD, (b) self- and observer ratings of psychopatology, (c) results coming from neuropsychological assessment of cognitive functions, and (d) multimodal brain imaging outcomes (WM integrity, functional connectivity, GM volumes).

It is expected that worsening or stabilization of mood, and the diagnosis of PPD, will be paralleled by worsening or stabilization of these measures, thus providing new markers to estimate the susceptibility to the disorder, to identify targets for treatment, and to predict and monitor treatment efficacy.

Inclusion Criteria:

-Signed informed consent, able to understand, speak and write the national language

Exclusion Criteria:

• History of bipolar disorder, schizophrenia, schizoaffective disorder, psychosis NOS; anorexia or bulimia nervosa;
• Taking following medications: antipsychotics, anticonvulsants, mood stabilizers, stimulants
• Active infection requiring antibiotics therapy;
• Immunosuppressed patient
• Other chronic diseases
• Signs of active infection requiring treatment
• Use of anti-inflammatory medication on a regular basis for a chronic inflammatory/autoimmune Disorder. - - Forbidden treatment: corticosteroids, NSAD, immunosuppressant IV-Ig based treatment
• Ongoing fever, infection treated by antibiotics or uncontrolled diabetes type I or II;
• Existing cancer or history of cancer in the last 5 years (except skin epidermoid cancer or in-situ cervix cancer);
• Known HIV infection or clinically manifest Acquired Immune Deficiency Syndrome (AIDS), Parkinson's or Alzheimer's disease, or any other serious condition likely to interfere e with the conduct of the trial;
• Abuse of drugs or alcohol in the past 6 months
• Presence of chromosomal disorders

150 pregnant women will be recruited in each center. We expect 15-30 women per group to develop PPD and be matched with HC in a 1:2 ratio, yielding a sample of 30-60 PPD patients and 60-120 HC.

Patients will be recruited at the Department of Obstetrics and Ginecology of Ospedale San Raffaele and at the Department of Woman, Children and Newborn (Clinica Mangiagalli), Fondazione IRCCS Ca' Granda Ospedale Maggiore Policlinico.

Patients will be recruited at the 20th week of gestation when patients fulfilling the inclusion criteria will be offered the possibility to participate to the study.