Abstract Objective To compare the gestational age of neonates in utero exposed to benzodiazepines (BDZs) with none exposed controls. Secondary objectives were; birth weight, presence of congenital malformations, APGAR score, and the need for > 3 months (prolonged) maternal psychiatric care. Study design A retrospective cohort study of women and neonates from 2013 to 2021 with univariate and multivariable analysis to study the associations between BDZs exposure and gestational age compared to non-exposed women with mental health problems. Results We found that BDZ exposure was associated with a lower gestational age of -3.2 days (95% CI -5.8 , -0.53 days). Women in the exposed group had an increased risk of psychiatric care (adjusted OR 2.511 (95% CI 1.675 – 3.782), p < 0.001). Conclusion We found that in utero BDZ exposure was independently associated with a significantly lower gestational age of the neonates and prolonged psychiatric care of their mothers.