Abstract
Thyroid disease affects a significant proportion of women of childbearing age and, when untreated, it may cause infertility, complications in pregnancy, and fetal developmental defects. Laboratory standards for thyroid parameters are different from those for the general population.
The most reliable and best standardized parameter in pregnancy is serum thyroid-stimulating hormone (TSH) which should be kept in the range of 0.1–2.5 mIU/L in the first trimester. Hypothyroidism in pregnancy must always be treated, with replacement therapy being initiated with a full dose and the TSH level maintained up to 2.5 mIU/L.
Propylthiouracyl is used to treat hyperthyroidism in pregnancy in the first trimester and methimazole is used since the second trimester and during breastfeeding. There is not sufficient evidence for systemic treatment of autoimmune thyroid disease without thyroid dysfunction in pregnancy and an individual approach is taken.
In all pregnant women at risk or those planning to become pregnant, screening for TSH and anti-thyroid peroxidase antibodies should be done in early pregnancy or before conception.