Idiopathic inflammatory myositis (IIM) is more prevalent in women of reproductive age. Both disease activity and the use of immunosuppressants may have a negative impact on fertility and pregnancy outcomes. Researchers investigated these effects in a group of women with IIM. Women with IIM aged 18 and above were questioned about their demographics, menstrual status, history of conception, results, and illness characteristics. Pregnancies occurring before and after the beginning of illness were compared. Eighty-one IIM patients were interviewed, with a median age of 32 years and an illness duration of 4 years. There were 45 individuals with dermatomyositis, 20 with polymyositis, and 16 with overlap myositis. During the 315.2 patient-years of follow-up, 63 individuals conceived prior to illness start, resulting in 205 pregnancies and 155 live births. Over 77.5 patient-years after illness started, there were 24 pregnancies in 7 women. One of the live babies had a cleft palate, one had a low birth weight, and one was premature. Antiphospholipid antibodies were not found in any of the patients who conceived. Obstetric and foetal problems were more common in pregnancies after the beginning of myositis, although there was no difference in maternal complications.

In the absence of clinical or serologic anti-phospholipid syndrome, women with IIM have poor foetal outcomes and a high risk of spontaneous abortion.