Pregnancy course and outcomes of patients with polymyositis and dermatomyositis (PM/DM) managed in a single center

We aimed to determine the association between disease activity during pregnancy and pregnancy outcomes of women with polymyositis and dermatomyositis (PM/DM). Patients with PM/DM who were managed from pregnancy to delivery at Kagawa University Hospital from March 2006 to May 2021 were enrolled. Clinical data were retrospectively analyzed to evaluate the association between disease activity during pregnancy and pregnancy outcomes. Eight pregnancies in 5 women with PM/DM were analyzed. The mean age at conception was 28.3 ± 3.8 years, and mean disease duration was 6.3 ± 3.2 years. Four patients required an increased glucocorticoid dosage because of worsening disease activity (sustained elevation of creatine phosphokinase [CPK] concentration). Two patients who continuously received immunosuppressive drugs from conception to delivery showed no increase in disease activity and did not need increased glucocorticoid dosages. The pregnancy outcomes were 1 spontaneous abortion and 7 live births. The mean gestation length was 35.3 ± 5.2 weeks, and mean birthweight was 2297.7 ± 1041.4 g. Five adverse pregnancy outcomes (APOs) occurred (2 preterm births and 4 low birthweights); most of these cases had sustained elevation of CPK concentration and increased glucocorticoid dosages. No APOs occurred in the 2 patients who received continuous immunosuppressive medication. Continued use of pregnancy-compatible medications and control of disease activity with lower glucocorticoid dosages in pregnancies with PM/DM may be important to achieve good pregnancy outcomes.