Acute myocardial infarction in pregnancy and the puerperium: a population-based study.

OBJECTIVE: To estimate the population-based incidence and pregnancy outcomes of acute myocardial infarction (MI) in pregnancy.

METHODS: Maternal and newborn hospital discharge records were linked to birth/death certificates for the 10-year period January 1, 1991, to December 30, 2000, for the majority (98%) of deliveries in California. This database was searched for the diagnosis of acute MI, demographic characteristics, and pregnancy outcomes. Patients were divided into 4 groups: antenatal diagnosis, intrapartum diagnosis, up to 6-week postpartum diagnosis, and those without the diagnosis of acute MI. All groups were compared by Student t test or chi(2) or both, where appropriate.

RESULTS: A total of 151 women had an acute MI during the antepartum (38%), intrapartum (21%), or 6-week postpartum (41%) period, giving an incidence rate of 1 in 35,700 deliveries. The incidence rate increased over the study period. The maternal mortality rate was 7.3%, and maternal death only occurred in women with an acute MI before or at delivery (P < .01). Compared with women who did not have an acute MI, those with one were more likely to be older (30% were older than 35 years compared with 10%), multiparous (78% compared with 61%), non-Hispanic white (40% compared with 35%) or African Americans (15% compared with 7%). All measures of maternal and neonatal morbidity were increased in the acute MI group compared with those without an acute MI. Multivariate analysis identified chronic hypertension, diabetes, advancing maternal age, eclampsia, and severe preeclampsia as independent risk factors for acute MI.

CONCLUSION: Acute MI during pregnancy remains a rare event, with significant maternal, fetal, and neonatal morbidity and mortality and maternal mortality limited to the antepartum and intrapartum period.