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Rheumatoid arthritis and risk of spontaneous abortion: a Danish nationwide cohort study


Nathan NO1,2, Mørch LS2, Wu CS3,4, Olsen J5,6, Hetland ML7,8, Li J5, Rom AL1,2. Rheumatology (Oxford). 2019 Nov 27. pii: kez565. doi: 10.1093/rheumatology/kez565. [Epub ahead of print]

Author Information

1 Department of Obstetrics.

2 Research Unit Women's and Children's Health, The Juliane Marie Centre, Copenhagen University Hospital, Rigshospitalet, Copenhagen.

3 Research Unit of Gynecology and Obstetrics, Institute of Clinical Research, University of Southern Denmark.

4 Department of Obstetrics and Gynecology, Odense University Hospital, Odense.

5 Department of Clinical Epidemiology, University of Aarhus, Aarhus, Denmark.

6 Department of Epidemiology, Fielding School of Public Health, University of California, Los Angeles, CA, USA.

7 Center for Rheumatology and Spine Diseases, Copenhagen Center for Arthritis Research, Rigshospitalet, Glostrup.

8 Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.



To investigate the influence of RA or preclinical RA on the risk of spontaneous abortion (SA) while taking age and duration of RA into consideration.


By linkage of data from Danish national registries, we established a nationwide cohort of pregnancies in Denmark from 1 January 1977 to 31 December 2014. We used multiple logistic regression to estimate; odds ratios (OR) for SA in women with RA or preclinical RA, compared with women without, and OR for SA by maternal age in women with RA or preclinical RA.


A total of 2 612 529 pregnancies were included. Women aged <35 years diagnosed with RA <5 years before pregnancy had an increased risk of SA (OR = 1.25 95% CI: 1.07, 1.48), compared with women without RA aged <35. Women at the same age diagnosed with RA ≥5 years before pregnancy had an OR of 1.14 (0.96-1.34), compared with women without. Among women with RA aged ≥35 years and women with preclinical RA at time of pregnancy, no increased risk of SA was found. The risk of SA increased by maternal age in both women with RA, preclinical RA and in women without.


Among women aged <35 years, the risk of SA was higher in women with RA compared with women without. After the age of 35 years, the risk of SA was no different from that among women without RA, even though the risk of SA increased with increasing age.