Optimal Care of the Pregnant Woman with Thyroid Disease

Pregnancy has a profound impact on the thyroid gland. During a normal pregnancy the thyroid increases in size, produces 50% more T4 and T3, requires 50% more iodine, and the normal TSH range is compressed with a lower limit of normal at both ends of the spectrum. It is therefore not surprising that pregnancy has been considered a physiological stress test for the thyroid gland (1). However, what has been striking is the research over the last 20 yr linking thyroid hormonal abnormalities and thyroid autoimmunity to a wide range of adverse pregnancy, maternal, and offspring outcomes including spontaneous miscarriage, gestational hypertension, preeclampsia, gestational diabetes, postpartum thyroiditis, and decreased IQ in the offspring. The rapidly evolving literature on the interaction between the thyroid and pregnancy was the impetus for an update of the 2007 Endocrine Society Guidelines (ES-G) (2). Included in the 2012 ES-G (3) are 27 articles published since the completion of the 2007 ES-G. Using a comprehensive and scholarly process, and the product of an international committee of experts in the field, the 2012 ES-G provide 52 recommendations for the care of the pregnant woman with thyroid disorders. The authors of the 2012 ES-G should be applauded for the high quality of the recommendations and their ability to synthesize data in a complex and rapidly evolving field.