Thyroid hormone has an important role in brain development of the baby during pregnancy. It is clear that overt hypothyroidism (increased TSH levels and low thyroid hormone levels) in the mother, especially early in pregnancy, can affect the baby’s brain development or cause other problems with the pregnancy. It is not clear if subclinical hypothyroidism (increased TSH levels and normal thyroid hormone levels) would have similar adverse effects. Previous studies that have been done on this topic have shown mixed results.
In the current study, the authors studied the effect of subclinical hypothyroidism detected before pregnancy on complications of pregnancy.
THE FULL ARTICLE TITLE:
Chen S et al. Preconception TSH levels and pregnancy outcomes: a population-based cohort study in 184,611 women. Clin Endocrinol (Oxf ). March 25, 2017 [Epub ahead of print].
SUMMARY OF THE STUDY
Between 2010 and 2012, 248,501 patients were enrolled in this study in 30 different provinces in China. A free exam is offered in rural china to couples planning pregnancy within 6 months. Before pregnancy, health related information and a blood test for TSH were obtained. In the study period, 194,154 pregnancies occurred, but subjects with pregnancy loss or twin and triple pregnancies and with TSH (obtained before pregnancy) level less than 0.48 and more than 10 mIU/l were excluded from the study. A total of 184,611 pregnant women who had a TSH level between 0.48 to 10 mIU/l before pregnancy were selected. These patients were divided into 3 groups: TSH level of 0.48 to 2.49 mIU/L (considered normal), TSH 2.5-4.29 mIU/L and TSH 4.3-10 mIU/L. The rate of pregnancy complications like miscarriage, premature delivery and caesarean delivery, as well as birth weight of their newborn compared between these groups.