A recent Argentine study has clarified the optimal starting dose of levothyroxine tablets (LT4) for patients with a primary diagnosis of hypothyroidism in pregnancy, thus helping to minimize the risk of pregnancy complications. The results of the study were published online in the journal Thyroid on November 11, 2013. Researcher Marcos Abalovich, MD, PhD, who works at the Durand Hospital in Buenos Aires, and colleagues noted that although recently published guidelines recommend strict compliance with TSH levels during pregnancy, the exact dose of levothyroxine tablets needed to meet the target is not specified. The latest Endocrine Society guidelines state that for patients diagnosed with hypothyroidism in pregnancy, a dose of 50 μg or more of levothyroxine is sufficient, but it is not clear whether this “50 μg or more” refers to 51 or 75 or 125 or some other value. The study provides a direction for endocrinologists to properly guide the treatment of hypothyroid patients in pregnancy. In current clinical practice guidelines, the recommended target values for treatment of subclinical hypothyroidism in pregnancy are: (1) TSH levels ≤2.5 mIU/L in early pregnancy; and (2) TSH levels ≤3.0 mIU/L in mid- to late-term pregnancy, a criterion that can significantly benefit patients with hypothyroidism in pregnancy, especially those with positive thyroid peroxidase antibodies. D., and colleagues concluded that for patients with a first diagnosis of hypothyroidism during pregnancy, it is recommended that levothyroxine tablets be initiated as follows: (1) 1.20 μg/kg/day for subclinical hypothyroidism with TSH levels <4.2 mIU/L; (2) 1.42 μg/kg/day for subclinical hypothyroidism with TSH levels <4.2-10 mIU/L; ( (3) 2.33 μg/kg/day for those with clinical hypothyroidism. With the above treatment regimen, the patient's thyroid function can be rapidly restored in a short period of time, thus reducing the risk of related pregnancy complications.