Background: Cardiovascular diseases, including acute coronary syndrome (ACS), are the leading cause of maternal death in many developed countries. Objectives: We assessed ACS incidences during pregnancy, peripartum and postpartum periods. We also compared overall pregnancy (i.e., covering all three periods) incidence with that in non-pregnant women of childbearing age. Study design: All women aged between 15 and 49 years old without ischemic heart disease who delivered between 2010 and 2018 in France were included in the CONCEPTION cohort. Data were extracted from the French National Health Insurance Information System database. ACS were defined according to the International Classification of Diseases-Tenth Revision codes recorded in the principal hospital diagnosis. We used Poisson regression to estimate crude ACS incidences, and tested age-adjusted Poisson models to compare the incidence risk ratio (IRR) of ACS between pregnant and non-pregnant women, with a 95% confidence interval (CI). Results: Among 6 298 967 deliveries in France, we observed 225 first time ACS diagnoses during overall pregnancy (overall pregnancy-related ACS incidence: 4.34 per 100 000 person-years, 1 case for 23 000 pregnancies). In multivariate analysis, independent factors associated with ACS were age, social deprivation, obesity, tobacco use, chronic hypertension and hypertensive disorders of pregnancy (all p100 million person-years). Compared with the ACS incidence in non-pregnant women, age-adjusted overall pregnancy-related ACS incidence was lower: IRR: 0.76 (95% CI: 0.57-0.98) (p