Andersen SL, et al. - Using Danish nationwide registers researchers conducted a population-based cohort study to assess the frequency of pregnancy loss in women with known hypothyroidism vs women with a later diagnosis of hypothyroidism and compared with other common endocrine diseases. In Denmark, all pregnancies resulting in live birth (n = 732,533), spontaneous abortion (n = 112,487) or stillbirth (n = 2937) were identified with information on maternal hypothyroidism, hyperthyroidism and diabetes. Investigators found that hypothyroidism increased the risk of early and late pregnancy losses, as did hyperthyroidism and diabetes in particular. They assumed that undetected or insufficiently treated maternal illness during pregnancy can be of causal importance.