The quality of maternal-foetal bonding may independently predict the quality of maternal-infant attachment and post-partum depressive and anxiety symptoms. A comprehensive assessment of maternal risk factors for perinatal psychopathology during pregnancy should include the evaluation of antenatal attachment that could be modifiable by specific interventions promoting the quality of maternal bonding.

Objectives: BRIDGE-II-MIX study aimed to estimate the frequency of mixed states in patients with MDE according to different definitions. This post-hoc analysis evaluates the association between obesity and the presence of mixed features and bipolarity. Methods: 2811 MDE subjects were enrolled in this multicentre crosssectional study. In 2744 patients, the body mass index (BMI) has been evaluated.Psychiatric symptoms, socio-demographic and clinical variables were collected, comparing the characteristics of MDE patients with (MDE-OB) and without obesity (MDE-NOB). Results: obesity (BMI ≥30) was registered in 493 patients (18%). In the MDE-OB group, 90 patients (20%) fulfilled DSM-IV-TR criteria for BD, 225 patients (50%) fulfilled the criteria for bipolarity specifier, 59 patients (13%) fulfilled DSM-5 criteria for MDE with mixed features and 226 patients (50%) fulfilled Research-Based Diagnostic Criteria for a mixed depressive episode. Older age, history of (hypo)manic switches during antidepressant treatment, the occurrence of three or more MDEs, atypical depressive features, antipsychotic treatment, female gender, depressive mixed state according to DSM-5 criteria, comorbid eating disorders and anxiety disorders were significantly associated with MDE-OB group. Among (hypo)manic symptoms during the current MDE, psychomotor agitation, distractibility, increased energy and risky behaviors were the variables most frequently associated with MDE-OB group.Conclusions: In our sample, the presence of obesity in patients with MDE seems to be associated with a lifetime diagnosis of BD. These findings suggest that obesity in patients with MDE could be considered a possible marker of bipolarity.