The dates of the father’s and/or mother’s filling of a prescription
for an antidepressant drug as well as outpatient
and/or inpatient hospital care records with a diagnosis of
depression were merged together as an indicator of depression.
The time intervals from each indication of depression
to the estimated conception date of the index birth were
calculated. Based on the time intervals, an indication of
having, or not having, paternal/maternal depression was
created for every 3-month period within the 24 months
before conception and/or during the first two trimesters of
pregnancy. Having any indication of depression from
12 months before conception until 24 completed weeks of
gestation was considered as having a preconception–early
pregnancy exposure to depression. This indicator was further
divided into ‘new depression’ and ‘recurrent depression’:
‘new depression’ was defined as an indication of
depression within a 3–month interval after 12 months with
no indication of depression; and ‘recurrent depression’ was
defined as all other cases.