Objectives Peripartum cardiomyopathy (PPCM) is a rare disease carrying a risk of death and chronic heart failure.It is unknown if women with PPCM have a family history of heart failure. We investigated the prevalence of heart failure and hypertension in first-degree relatives to women with PPCM.

Methods A cohort of 61 women with PPCM was identified through the nationwide Danish registers from 2005 to 2014, and each individual diagnosis of PPCM was validated through review of patient records. We excluded 13 women due to lack of data on relatives. In a case–control design, the 48 remaining women were matched (on age, year of childbirth, parity and number of siblings) to 477 birth-giving Danish women without heart failure. We obtained information on first-degree relatives (parents and siblings) through the National Danish Registers.

Results The cohort of 48 women with PPCM had a mean age of 31 years (SD 6). The prevalence of heart failure in any first-degree relative was higher in women with PPCM, compared with controls (23% vs 10%, p=0.011). A first-degree relative with any cardiovascular diagnosis was not more frequent in women with PPCM versus controls (77% vs 70%, p=0.280), but for siblings only, any cardiovascular diagnosis was more frequent in siblings to women with PPCM (29% vs 16%, p=0.026).

Conclusion Having a first-degree relative with heart failure was significantly more frequent in a cohort of validated PPCM cases than in controls, supporting the notion of shared aetiology between PPCM and other forms of heart failure.