Dilated cardiomyopathy 1X (CMD1X) is characterized by dilated cardiomyopathy (DCM) with mildest limb-girdle muscle symptoms and normal intelligence. Compound heterozygous mutation in fukutin gene is known as its genetic cause. Here, we report a pregnancy case complicated with CMD1X. A 25-year-old primiparous woman, who had been diagnosed as CMD1X at the age of 19, was referred to our hospital at 6 weeks of gestation. In early pregnancy, the evaluation of her cardiac function showed ejection fraction 47% and NYHA class II. Worsening of cardiac function was observed from 30 weeks, manifesting reduced cardiac load with left ventricular dilatation and in-hospital bed rest was necessary. Elective cesarean section was performed at 35 weeks to prevent deterioration of cardiac function. The parameters of her cardiac function returned to the pre-pregnancy status in a month after delivery, whereas she realized persistent worsening of muscular weakness at postpartum.