Abstract
Objective: The primary objectives of this study are to compare the rates of preterm birth; fetal growth restriction and low birth weight between the following groups: (1) pregnant women treated for thyrotoxicosis and low-risk pregnancies; (2) between pregnant women with thyrotoxicosis with no need of medication and low-risk pregnancies; and (3) between those treated with MMI and PTU. Methods: The medical records of singleton pregnancies with thyrotoxicosis were comprehensively reviewed. Low-risk pregnancies matched for age and parity were randomly recruited as controls. The obstetric outcomes were compared between both groups; the outcomes of various subgroups of the thyrotoxicosis group were also compared. Results: A total of 408 pregnant women with thyrotoxicosis were recruited. Compared with the controls; the women of the thyrotoxicosis group had significantly higher rates of low birth weight (LBW) (23.7% vs. 17.7%; p: 0.036), preterm birth (19.3% vs. 12.3%; p: 0.007), preeclampsia (8.5% vs. 4.4%; p: 0.019) and cesarean section (21.5% vs. 16.0%; p: 0.046). In the thyrotoxicosis group; 67; 127; and 158 patients were treated with MMI; PTU and no anti-thyroid drug (ATD), respectively. All obstetric outcomes were comparable between the women treated with PTU and those with MMI; and between the controlled and uncontrolled groups. However, women who needed ATD had significantly higher rates of LBW and preterm birth than those without medications. Conclusions: Thyrotoxicosis, whether treated or not needing ATDs, was significantly associated with an increased risk of adverse pregnancy outcomes. Also, active disease, indicated by the need for ATD significantly increased the risk of such adverse outcomes; whereas the patients treated with MMI or PTU had comparable adverse outcomes.
Highlights
Thyrotoxicosis is a condition involving the thyroid gland producing and secreting excessive amounts of thyroid hormone
The primary objectives of this study are to compare the rates of preterm birth, fetal growth restriction and low birth weight between the following groups: (1) pregnant women treated for thyrotoxicosis and low-risk pregnancies, (2) between pregnant women with thyrotoxicosis with no need of medication and low-risk pregnancies, and (3) between those treated with MMI and PTU
Patients in the thyrotoxicosis group were categorized into three groups based on the main type of anti-thyroid drugs (ATD) used: PTU (n = 128), MMI (n = 67), no ATD treatment (n = 158) and heterogeneous data (n = 55; mixed use of ATDs, or switched to each other)
Summary
Thyrotoxicosis is a condition involving the thyroid gland producing and secreting excessive amounts of thyroid hormone. Pregnancy complicated with poorly controlled thyrotoxicosis is associated with an increased risk of adverse pregnancy outcomes, including, spontaneous abortion, preterm birth, low birth weight, stillbirth, fetal hypothyroid and hyperthyroid [2,3]. Maternal complications such as preeclampsia, heart failure and thyroid storm are increased [4,5]. In actual practice, most cases of pregnancies with thyrotoxicosis are under control, and adverse pregnancy outcomes among patients treated for thyrotoxicosis have not been well-established [2,3]. Regarding the two most commonly used ATDs, methimazole (MMI)
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