Thyroid hormones are essential both for the physiological course of pregnancy and for the optimal differentiation of the embryonic tissues and foetal brain development. Overt and subclinical hypothyroidism constitutes a frequent cause of infertility, it carries along an increased risk of spontaneous abortion and premature birth, and it may lead to an impaired foetal brain development resulting in a worse psychoneurological outcome in the progeny. The repeatedly documented high prevalence of thyroid diseases in pregnancy warrants a realization of systematic screening for thyroid dysfunction during early stage of pregnancy or better before conception whenever possible. The Czech Endocrine Society attempts to implement such a systematic screening in the Czech Republic, although the particular aspects of the screening are still discussed.

        Key words: pregnancy, thyroid stimulating hormone, thyroid dysfunction, antibodies to thyroid peroxidase.