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. 2019 Nov 18;14(11):e0225133. doi: 10.1371/journal.pone.0225133

Table 1. Classification of exposures.

Exposure ATC Timeframe
SSRI [any]
≥1 SSRI [any] prescription in trimesters 2 or 3		 N06AB From 92 days after the first day of LMP to birth
High dose SSRI
≥1 high dose SSRI [any] prescription t2-3 [defined as tablet sizes: 60mg fluoxetine, 40mg citalopram, 30mg paroxetine, 100mg sertraline, 20mg escitalopram]		 N06AB From 92 days after the first day of LMP to birth
Antidepressant [any]
≥1 Antidepressant prescription trimesters 2 or 3 t2-3*		 N06A From 92 days after the first day of LMP to birth
SNRI [any]
≥1 prescription for an SNRI in trimesters 2 or 3		 Venlafaxine N06AX16, reboxetine N06AX18, duloxetine N06AX21 From 92 days after the first day of LMP to birth
Depression diagnosis in the primary care record whilst on the database - Any time before the end of trimester 1 [91 days after 1st day of LMP]
Unmedicated depression Depression diagnosis recorded [as above] but no antidepressant prescribed in trimesters 2 or 3 [t2-3].
Medicated depression N06A Depression diagnosis recorded [as above] plus an antidepressant in trimesters 2 or 3 [t2-3].
Discontinued SSRI:
≥1 SSRI prescription in trimester 1, but not in trimesters 2 or 3		 N06AB Prescription between 1st day LMP and 91 days after 1st day LMP] and no further prescriptions recorded throughout pregnancy
Discontinued antidepressant:
≥1 prescription of any antidepressant in trimester 1, but not in trimesters 2 or 3		 N06A Prescription between 1st day LMP and 91 days after 1st day LMP] and no further prescriptions recorded throughout pregnancy

LMP—last menstrual period, SSRI–selective serotonin reuptake inhibitor, SNRI–serotonin and noradrenaline reuptake inhibitor

Medicines were defined by ATC codes, and then matched to version 2 Read codes in the GP database, using reference data provided by NHS Digital Technology Reference Data Update Distribution [https://isd.digital.nhs.uk/trud3/user/guest/group/0/home].