Heart failure after pregnancy caused by a disorder of the heart muscle. The cause is unknown. The condition occurs mostly in women over age 30 who have had several pregnancies or in women who have had preeclampsia, eclampsia, or a multiple pregnancy. Postpartum cardiomyopathy usually occurs in the first month after childbirth, but it can occur as much as 5 months later. Symptoms include moderate respiratory distress and left-sided chest pain.