[Screening pregnant women for hypothyroidism: as yet only in high risk groups].

Several recent publications have drawn attention to the possible relationship between a lowered serum thyroxine concentration in pregnant women and subsequent retarded neuropsychological development of their children. Experimental evidence suggests that circulating maternal thyroxine is an important source of thyroid hormone for the developing foetal brain during the first trimester. These considerations have led some authors to advocate a population-based screening program for hypothyroidism in pregnancy. However, at present it is unclear when such screening should take place, which screening test should be used, and what the benefit of therapeutic intervention is in terms of neuropsychological outcome. At present, screening seems not warranted, but we would advocate case finding of (subclinical) auto-immune hypothyroidism in certain risk groups (e.g., positive family history for auto-immune thyroid disease, or presence of type 1 diabetes mellitus) since treatment in these cases is warranted. The establishment of the optimal timing and nature of screening for hypothyroidism in pregnant women and of its cost-effectiveness is an attractive goal for a research project in a defined region.