Thyroid autoimmunity and miscarriage: a meta-analysis

P>Objective To investigate whether thyroid autoimmunity (TAI) is associated with increased risk of miscarriage in euthyroid women. Methods An electronic search was conducted using the databases Medline, PubMed, EMBASE and the Cochrane library, from inception to October 2010. A systematic review of the studies on the association between TAI and miscarriage was performed. The odd ratios of case-control studies and relative risks of cohort studies were pooled respectively. The software Review Manager (version 4.3.1) was applied for meta-analysis. Results The search strategy identified 53 potentially relevant publications, 22 of which were included in the meta-analysis. A clear association between thyroid autoimmunity and miscarriage was observed with a pooled odds ratio of 2 center dot 55 (95% CI 1 center dot 42-4 center dot 57, P = 0 center dot 002) in eight case-control studies and a pooled relative risk of 2 center dot 31 (95% CI 1 center dot 90-2 center dot 82, P < 0 center dot 000 01) in 14 cohort studies. Women with TAI were found to have slightly higher age [age difference, 1 center dot 29 years] (95% CI 0 center dot 43-2 center dot 16, P = 0 center dot 003) and thyroid-stimulating hormone (TSH) levels [TSH difference, 0 center dot 61 mIU/l] (95% CI 0 center dot 51-0 center dot 71, P < 0 center dot 000 01) compared with those without TAI. Conclusion Based on the currently available evidence, it appears that the presence of thyroid autoimmunity is associated with an increased risk of spontaneous miscarriage in euthyroid women.