ARTHRITIS & RHEUMATISM Vol. 63, No. 6, June 2011, pp 1534–1542 DOI 10.1002/art.30210 © 2011, American College of Rheumatology Pregnancy and Delivery in Women With Chronic Inflammatory Arthritides With a Specific Focus on First Birth Marianne Wallenius, 1 Johan F. Skomsvoll, 1 Lorentz M. Irgens, 2 Kjell Å. Salvesen, 1 Bjorn Y. Nordva ˚g, 3 Wenche Koldingsnes, 4 Knut Mikkelsen, 5 Cecilie Kaufmann, 6 and Tore K. Kvien 7 Objective. To examine possible associations be- tween chronic inflammatory arthritides and pregnancy outcomes with separate analyses of first and subsequent births before and after diagnosis. Methods. Linkage of data from a registry of patients with chronic inflammatory arthritides and the Medical Birth Registry of Norway enabled a comparison of pregnancy outcomes in women with chronic inflam- matory arthritides and pregnancy outcomes in reference subjects. Outcomes of first birth and subsequent births before and after diagnosis were analyzed separately. Associations between chronic inflammatory arthritides and the women’s health during pregnancy and delivery as well as perinatal outcomes were assessed in logistic regression analyses with adjustments for maternal age at delivery and gestational age. Results. We analyzed 128 first births and 151 subsequent births after diagnosis and 286 first births and 262 subsequent births before diagnosis in patients and compared them with first and subsequent births in reference subjects. Firstborn children of women diag- nosed as having chronic inflammatory arthritides were more often preterm (odds ratio [OR] 1.85 [95% con- fidence interval (95% CI) 1.09–3.13]) and small for gestational age (OR 1.60 [95% CI 1.00–2.56]). They also had lower mean birth weight (P  0.01) and higher perinatal mortality (OR 3.26 [95% CI 1.04–10.24]). Birth by caesarean section (all classifications) was more frequent in patients than in reference subjects, and elective caesarean section was 2-fold more frequent in patients, both in first birth (OR 2.60 [95% CI 1.43–4.75]) and in subsequent births (OR 2.18 [95% CI 1.33–3.58]). No excess risks of clinical importance were observed prior to diagnosis of chronic inflammatory arthritides. Conclusion. Excess risks were related to first birth in women diagnosed as having chronic inflamma- tory arthritides, including a higher rate of perinatal mortality. A higher caesarean section rate was related to all patient deliveries. Mainly, pregnancy outcomes be- fore diagnosis did not differ from those in reference subjects. It is increasingly recognized that autoimmunity can affect every aspect of pregnancy, such as fertiliza- tion, maternal complications, and adverse fetal out- comes (1). Pregnancy may also influence autoimmune diseases. An ameliorating effect of pregnancy on chronic inflammatory arthritides has been reported (2–8). Sev- eral studies have addressed possible effects of chronic inflammatory arthritides on pregnancy and delivery (9– 22). Excess rates of caesarean section have been re- ported in patients with chronic inflammatory arthritides (9,10,12,15–17,21). Furthermore, excess rates of pre- eclampsia (12,19,21,22), preterm delivery (17,19,20), in- Supported by the Liaison Committee between the Central Norwegian Regional Health Authority and the Norwegian University of Science and Technology. The NOR-DMARD registry has received research grants from Abbott, Amgen, Aventis, Bristol-Myers Squibb, MSD, Roche, Schering-Plough/Centocor, Wyeth, and the Norwegian Directorate for Health and Social Affairs. 1 Marianne Wallenius, MD, Johan F. Skomsvoll, MD, PhD, Kjell Å. Salvesen, MD, PhD: Trondheim University Hospital and Norwegian University of Science and Technology, Trondheim, Nor- way; 2 Lorentz M. Irgens, MD, PhD: Medical Birth Registry of Norway, Norwegian Institute of Public Health, and University of Bergen, Bergen, Norway; 3 Bjorn Y. Nordvåg, MD, PhD, MPH: Trondheim University Hospital, Trondheim, Norway; 4 Wenche Koldingsnes, MD, PhD: University Hospital, Northern Norway, Tromsø, Norway; 5 Knut Mikkelsen, MD: Lillehammer Hospital for Rheumatic Diseases, Lille- hammer, Norway; 6 Cecilie Kaufmann, MD: Buskerud Central Hospi- tal, Drammen, Norway; 7 Tore K. Kvien, MD, PhD: Diakonhjemmet Hospital, Oslo, Norway. Dr. Kvien has received consulting fees, speaking fees, and/or honoraria from MSD, Roche, Bristol-Myers Squibb, UCB, and Pfizer (less than $10,000 each). Address correspondence to Marianne Wallenius, MD, De- partment of Rheumatology, Bevegelsessenteret, St. Olav’s Hospital, Trondheim University Hospital, N-7006 Trondheim, Norway. E-mail: marianne.wallenius@ntnu.no. Submitted for publication June 28, 2010; accepted in revised form December 14, 2010. 1534