Peter Laurberg1, Stine Linding Andersen2. 1. Department of EndocrinologyAalborg University Hospital, DK-9000 Aalborg, DenmarkDepartment of Clinical MedicineAalborg University, Aalborg, DenmarkDepartment of EndocrinologyAalborg University Hospital, DK-9000 Aalborg, DenmarkDepartment of Clinical MedicineAalborg University, Aalborg, Denmark peter.laurberg@rn.dk. 2. Department of EndocrinologyAalborg University Hospital, DK-9000 Aalborg, DenmarkDepartment of Clinical MedicineAalborg University, Aalborg, DenmarkDepartment of EndocrinologyAalborg University Hospital, DK-9000 Aalborg, DenmarkDepartment of Clinical MedicineAalborg University, Aalborg, Denmark.
Abstract
BACKGROUND: Antithyroid drugs (ATDs) may have teratogenic effects when used in early pregnancy. OBJECTIVE: To review the association between the time period of ATD exposure in early pregnancy and the development of birth defects. METHODS: We identified publications on birth defects after early pregnancy exposure to the ATDs methimazole (MMI; and its prodrug carbimazole (CMZ)) and propylthiouracil (PTU). Cases of birth defects after ATD treatment had been initiated or terminated within the first 10 weeks of pregnancy were identified and studied in detail. RESULTS: A total of 92 publications were read in detail. Two recent large controlled studies showed ATD-associated birth defects in 2-3% of exposed children, and MMI/CMZ-associated defects were often severe. Out of the total number of publications, 17 included cases of birth defects with early pregnancy stop/start of ATD treatment, and these cases suggested that the high risk was confined to gestational weeks 6-10, which is the major period of organogenesis. Thus, the cases reported suggest that the risk of birth defects could be minimized if pregnant women terminate ATD intake before gestational week 6. CONCLUSION: Both MMI and PTU use in early pregnancy may lead to birth defects in 2-3% of the exposed children. MMI-associated defects are often severe. Proposals are given on how to minimize the risk of birth defects in fertile women treated for hyperthyroidism with ATDs.
BACKGROUND: Antithyroid drugs (ATDs) may have teratogenic effects when used in early pregnancy. OBJECTIVE: To review the association between the time period of ATD exposure in early pregnancy and the development of birth defects. METHODS: We identified publications on birth defects after early pregnancy exposure to the ATDs methimazole (MMI; and its prodrug carbimazole (CMZ)) and propylthiouracil (PTU). Cases of birth defects after ATD treatment had been initiated or terminated within the first 10 weeks of pregnancy were identified and studied in detail. RESULTS: A total of 92 publications were read in detail. Two recent large controlled studies showed ATD-associated birth defects in 2-3% of exposed children, and MMI/CMZ-associated defects were often severe. Out of the total number of publications, 17 included cases of birth defects with early pregnancy stop/start of ATD treatment, and these cases suggested that the high risk was confined to gestational weeks 6-10, which is the major period of organogenesis. Thus, the cases reported suggest that the risk of birth defects could be minimized if pregnant women terminate ATD intake before gestational week 6. CONCLUSION: Both MMI and PTU use in early pregnancy may lead to birth defects in 2-3% of the exposed children. MMI-associated defects are often severe. Proposals are given on how to minimize the risk of birth defects in fertile women treated for hyperthyroidism with ATDs.
Authors: Murali K Mallela; Marie Strobl; Ryan R Poulsen; Christopher C Wendler; Carmen J Booth; Scott A Rivkees Journal: Birth Defects Res B Dev Reprod Toxicol Date: 2014-06-30
Authors: Joan C Lo; Scott A Rivkees; Malini Chandra; Joel R Gonzalez; James J Korelitz; Michael W Kuzniewicz Journal: Thyroid Date: 2015-04-14 Impact factor: 6.568