Participants
We performed a nested case-control study within the IGEDEPP (“Gene-Environment Interaction in PPD”) prospective cohort. IGEDEPP enrolled 3310 Caucasian women in eight maternity departments in the Paris metropolitan area in France, between November 2011 and June 2016. Caucasian cohort participants were selected in order to remove potential confounding factors for genetic analysis. Other main inclusion criteria were: age over 18, and delivery after 32 weeks of amenorrhea. Exclusion criteria included mental retardation, dementia or schizophrenia. Women were included in the study at the maternity department between the second and the fifth day after delivery and were evaluated at three time points by specially trained clinicians, over the course of one year. The first assessment took place at the maternity department between the second and fifth day after delivery in a face-to-face interview; the second at 8 weeks postpartum, by phone; the third at one year postpartum, also by phone. Among the 3310 women, 91.1% (n=3015) were assessed at 8 weeks postpartum, and 71.0 % (n=2351) were assessed at 1 year postpartum. Clinical characteristics of the sample have been described in previous work (29).
The research protocol (ClinicalTrials.gov Identifier: NCT01648816) was approved by the Data Protection and Freedom of Information Commissions and the French Ethics Committee (Ile de France I). All women received oral and written information regarding the study and signed a consent form.