Autoimmune diseases and adverse pregnancy outcomes: an umbrella review.

Background: The prevalence of autoimmune conditions is two-fold higher in women than in men, especially during the reproductive years. Autoimmune conditions have been associated with a greater risk of adverse pregnancy outcomes, and some conditions have been studied more than others with inconsistent findings. The objective of this umbrella review was to identify, appraise, synthesise, and consolidate findings from published systematic reviews of autoimmune conditions and adverse pregnancy outcomes.

Methods: In this umbrella review, we searched Medline, Embase, and Cochrane databases for systematic reviews from inception to Sept 30, 2022, without language restrictions. We used the Medical Subject Headings and free text search for autoimmune conditions and pregnancy outcomes. Screening, data extraction, and quality appraisal (AMSTAR 2) were done by two independent reviewers. Data was extracted using a standardised form, which was piloted before use. Data were synthesised narratively and quantitatively. Odds ratios (ORs) with 95% CIs were reported. The protocol has been registered to PROSPERO (CRD42022334992).

Findings: We selected 33 reviews, which included 709 primary studies. Pregnant women with autoimmune conditions were at high risk of both adverse maternal and fetal outcomes. The risk of miscarriage was increased in pregnant women with Sjögren's syndrome (relative risk [RR] 8·85, 95% CI 3·10-25·26), systemic lupus erythematosus (SLE; OR 4·90, 95% CI 3·10-7·69), thyroid autoimmunity (OR 2·77, 2·10-3·65), systemic sclerosis (OR 1·60, 1·29-2·22), and coeliac disease (OR 1·38, 1·12-1·69). The risk of pre-eclampsia was increased in pregnant women with type 1 diabetes (T1DM; OR 4·19, 3·08-5·71) and SLE (OR 3·20, 2·54 - 4·20). The risk of gestational diabetes was increased in pregnant women with inflammatory bowel disease (IBD; OR 2·96, 1·47-5·98) and thyroid autoimmunity (OR 1·49, 1·07-2·07). The risk of intrauterine growth restriction (IUGR) was increased in pregnant women with systemic sclerosis (OR 3·20, 2·21-4·53) and coeliac disease (OR 1·71, 1·36-2·14). The risk of delivering a small-for-gestational age baby was increased in pregnant women with SLE (OR 2·49, 1·88-3·31) and rheumatoid arthritis (OR 1·49, 1·22-1·82). The risks of other fetal outcomes such as stillbirth, preterm birth, and low birthweight were also increased in pregnant women with autoimmune disorders. T1DM in women was associated with lower odds of small-for-gestational-age outcome (OR 0·68, 0·56-0·83).

Interpretation: Pregnant women with autoimmune conditions are at greater risk of developing adverse pregnancy outcomes. Further research is required to develop better preconception to post-natal care for women with autoimmune conditions.

Funding: Medical Research Council (MRC) and the National Institute for Health and Care Research (NIHR).