POS1424 PREGNANCY COURSE IN A COHORT OF WOMEN WITH MYOSITIS - RESULTS FROM REVNATUS
Authors: B. Jakobsen, H. Bjørngaard, H. S. Koksvik, T. T. Pedersen, M. Wallenius
Journal: Annals of the Rheumatic Diseases (2021)

Background: Myositis is a rare autoimmune disease characterized by proximal and symmetrical muscle weakness and inflammatory infiltrates on muscle biopsy, and may affect women in reproductive age. Only few reports exist on pregnancy outcomes in women with myositis. Well-controlled disease at time of conception seems to give better outcome for the mother and the fetus (1). Inflammatory active disease before and during pregnancy has been associated with preterm birth and infant small for gestational age (1). Objectives: To describe the course of pregnancy in patients with myositis. Methods: We prospectively collected data on pregnancy in women with myositis in the nationwide Norwegian quality registry - RevNatus. ICD-10 codes: ICD-10 M33.0 (5), M33.1 (2), M33.2 (1), M33.9 (3). Eleven pregnancies in ten women with a known pregnancy outcome from 2016 – 2020 were included. Results: Median disease duration was 10 years (range 3-26), and median age at conception was 29 years (range 25-43). Five women had juvenile myositis. Two pregnancies ended in spontaneous abortions, one in 1 st trimester and one in 2 nd trimester. Nine pregnancies ended with live birth at median pregnancy week 39 (range 35-41) and a median birth weight of 3355 gram (range 2580-4750). None of the women experienced preeclampsia or HELLP. Three women was positive for ANA. Median CRP in second trimester was three (range 0-7). Among nine women with live births, seven were in remission, and two women had persistent disease in second trimester, defined by rheumatologist. Seven women used DMARDs in pregnancy, and two women used prednisolone 5 mg throughout pregnancy. Patient # Pregnancy # Maternal age at conception Disease duration years Medication during pregnancy Disease activity 2 nd trimester Gestational age at delivery Infant birth weight (gram) Delivery mode A 1 29 25 none Remission 38 3355 Standard vaginal delivery B 2 34 7 azathioprine Persistent 39 3725 Standard vaginal delivery C 3 29 15 azathioprine Spontaneous abortion week 7 D 4 35 3 ciclosporin prednisolone 5mg Persistent 40 3000 Standard vaginal delivery E 5 28 13 none Remission 37 2765 Operational vaginal delivery F 6 25 10 azathioprine hydroxy-chloroquine Remission 41 4085 Standard vaginal delivery F 7 27 13 azathioprine hydroxy-chloroquine Remission 41 3815 Standard vaginal delivery G 8 36 13 prednisolone 5mg Spontaneous abortion &gt; week 12 H 9 29 9 azathioprine Remission 35 2580 Standard vaginal delivery I 10 43 5 azathioprine prednisolone 5mg Remission 37 3140 Sectio J 11 36 28 none Remission 41 4750 Acute sectio Conclusion: We did not observe disease flare during pregnancy and no serious adverse outcomes in the pregnancies ending with live births. However, data are sparse, and larger cohorts are necessary to evaluate possible risk factors. References: 1. Munira S, Christopher-Stine L. Pregnancy in myositis and scleroderma. Best Pract Res Clin Obstet Gynaecol. 2020 Apr;64:59-67. doi: 10.1016/j.bpobgyn.2019.10.004. Epub 2019 Oct 18. PMID: 31928915. Disclosure of Interests: None declared