Thyroid autoantibodies, miscarriage, and preterm delivery in euthyroid women

January 01, 0001

Thyroid autoantibodies, miscarriage, and preterm delivery in euthyroid women

Hypothyroidism is associated with poor pregnancy outcomes. These British researchers examined thyroid autoantibodies and the risk of miscarriage and preterm birth in pregnant euthyroid patients via a systematic review and meta-analysis. They searched Medline, Embase, Cochrane Library, and SCISEARCH without language restrictions for cohort and case-control studies yielding 31 studies with 12 126 women looking at miscarriage, and an additional five studies with 12?566 women evaluated the association with preterm birth.

The researchers found: "Of the 31 studies evaluating miscarriage, 28 showed a positive association between thyroid autoantibodies and miscarriage. Meta-analysis of the cohort studies showed more than tripling in the odds of miscarriage with the presence of thyroid autoantibodies (odds ratio 3.90). For case-control studies the odds ratio for miscarriage was 1.80). There was a significant doubling in the odds of preterm birth with the presence of thyroid autoantibodies (2.07). Two randomised studies evaluated the effect of treatment with levothyroxine on miscarriage. Both showed a fall in miscarriage rates, and meta-analysis showed a significant 52% relative risk reduction in miscarriages with levothyroxine (relative risk 0.48). One study reported on the effect of levothyroxine on the rate of preterm birth, and noted a 69% relative risk reduction (0.31)."

The researchers concluded: "The presence of maternal thyroid autoantibodies is strongly associated with miscarriage and preterm delivery. There is evidence that treatment with levothyroxine can attenuate the risks."

Thyroid autoantibodies are associated with poor pregnancy outcomes even when thyroid function is intact.

For the full abstract, click here.

BMJ 342:d2616, 9 May 2011
© 2011 BMJ Publishing Group Ltd.
Association between thyroid autoantibodies and miscarriage and preterm birth: meta-analysis of evidence. Shakila Thangaratinam, Alex Tan, Ellen Knox, Mark D Kilby, Jayne Franklyn, Arri Coomarasamy. Correspondence to A Coomarasamy:

Category: T. Endocrine/Metabolic/Nutritional, W. Pregnancy, Family Planning. Keywords: thyroid autoantibodies, pregnancy, miscarriage, preterm delivery, levothryoxine, systematic review and meta-analysis, journal watch.
Synopsis edited by Dr Paul Schaefer, Toledo, Ohio. Posted on Global Family Doctor 31 May 2011

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