Exposures of paternal and maternal depression
The dates of filling the prescription of antidepressant
medication were obtained from the National Drug Register,
and antidepressants were identified according to the
World Health Organization’s anatomical therapeutic
chemical (ATC) classification of N06A. Dates of outpatient
care and inpatient hospital admissions with a
depression diagnosis for the mother and/or father were
retrieved from the Patient Discharge Register, which
includes nationwide information on the dates and diagnoses
of all hospital inpatient and outpatient care since
2001. Depression in care was defined as a visit or a hospital
admission with a main or complimentary diagnosis,
using the tenth revision of the International Classification
of Diseases (ICD–10). All main or complimentary diagnoses
with a mood disorder (ICD–10 codes F32–F39)
were included in our concept of depression. For all our
exposures (filling a drug prescription, and outpatient and
inpatient care), an observation period of at least
24 months before conception was available, with an earliest
observation date of 1 July 2005, when the National
Drug Register was created.