Factors associated with the change in prevalence of cardiomyopathy at delivery in the period 2000–2009: a population‐based prevalence study

Objective Cardiomyopathy ( CM ) at delivery is increasing in prevalance. The objective of this study was to determine which medical conditions are attributable to this increasing prevalance. Design Population prevalence study from 2000 to 2009. Setting The Nationwide Inpatient Sample ( NIS ). Sample Pregnant women admitted for delivery were identified in the NIS for the years 2000–2009. Methods Temporal trends in pre‐existing medical conditions and in medical and obstetric complications at delivery admissions were determined by linear regression. The change in the prevalence of CM among all pregnant women was compared with the change in the prevalance of CM among pregnant women without pre‐existing conditions or complications. Main outcome measure Prevalence of CM . Results The prevalence of CM increased from 0.25 per 1000 deliveries in 2000 to 0.43 per 1000 deliveries in 2009 ( P < 0.0001). Women with chronic hypertension had increased odds of developing CM compared with women without chronic hypertension (odds ratio, OR , 13.2; 95% confidence interval, 95% CI , 12.5–13.7). The linear increase in chronic hypertension over the 10‐year period was the single identified pre‐existing medical condition that explained the increasing prevalence of CM at delivery ( P = 0.005 for the differences in slopes for linear trends). Conclusions Pregnant women with chronic hypertenion are at an increased risk for CM at delivery, and the increasing prevalence of chronic hypertension is an important factor associated with the increasing prevalence of CM at the time of delivery. Among women without chronic hypertension, the prevalence of CM at delivery did not change during the time period.