INTRODUCTION: The aim of this study was to assess the association between multivitamin intake during pregnancy and the risk of preterm birth and very preterm birth. METHODS: The study population comprised 15,629 women from the Copenhagen Pregnancy Cohort with data on pregnancy multivitamin intake during their first trimester who gave birth to singletons from October 2012 to October 2016. Data on pregnancy multivitamin intake were linked to the Medical Birth Registry to identify the birth outcome. The main outcome measures were preterm birth before 37 weeks of gestation and very preterm birth before 32 weeks of gestation. RESULTS: Among the included women, 85.6% had taken daily pregnancy multivitamins during their first trimester. We found no evidence that pregnancy multivitamin intake during the first trimester was associated with a decreased risk of preterm birth (adjusted odds ratio (OR) = 1.01; 95% confidence interval (CI): 0.77-1.33) or very preterm birth (adjusted OR = 1.06; 95% CI: 0.63-1.77). Stratification for BMI into < 25 kg/m² and ≥ 25 kg/m² did not alter these findings. CONCLUSIONS: Pregnancy multivitamin intake during the first trimester was not associated with a decreased risk of preterm birth or very preterm birth among women in a high-income population.