Outcomes
We compared the exposed and reference group using gestational age (days) as the primary outcome. Secondary outcomes were birth weight, APGAR scores at 1 and 5 minutes, presence of congenital malformations, and prolonged psychiatric care defined as > 3 months postpartum psychiatric care.
Congenital malformations were divided into minor and major malformations according to EUROCAT guidelines if an ICD-10 codes class XVII (Q00-99) was recorded in the EPF. Prolonged psychiatric care of the mother was defined as more than 3 months postpartum, which is the normal follow-up time. The severity of the underlying mental disorder was estimated by the total number of registered mental disorders.
The reference group consisted of pregnancies of women with any mental disorder not using a BDZ at any time during pregnancy.