From the FDA Drug Label
Hypothyroidism during pregnancy is associated with a higher rate of complications, including spontaneous abortion, pre-eclampsia, stillbirth and premature delivery. Since postpartum TSH levels are similar to preconception values, the Levothyroxine Sodium Tablets, USP dosage should return to the pre-pregnancy dose immediately after delivery.
The dosage of levothyroxine should return to the pre-pregnancy dose immediately after delivery, which implies that it is okay to use after a miscarriage. There is no difference in this context between levothyroxine and Synthroid as they are the same medication, levothyroxine 1.
From the Research
Levothyroxine and Synthroid are essentially the same medication and are equally appropriate to use after a miscarriage if you have hypothyroidism, with no clinical difference between generic levothyroxine and brand-name Synthroid in terms of safety or effectiveness following pregnancy loss. The most important consideration is maintaining consistent thyroid hormone levels, so it's generally recommended to stick with whichever formulation you were using before rather than switching between brands. After a miscarriage, your doctor may need to adjust your dosage as hormone levels change, typically checking thyroid function tests 4-6 weeks after the event 2. Proper thyroid hormone replacement is actually crucial following pregnancy loss, as untreated hypothyroidism can affect future fertility and pregnancy outcomes. If you're planning to conceive again, maintaining optimal thyroid function with either medication is important, with a target TSH typically below 2.5 mIU/L for women trying to conceive.
Some studies have investigated the effect of levothyroxine on pregnancy outcomes in women with thyroid autoimmunity or hypothyroidism. For example, a study published in 2019 found that levothyroxine treatment did not result in a higher rate of live births than placebo in euthyroid women with thyroid peroxidase antibodies 3. Another study published in 2017 also found that levothyroxine treatment did not reduce miscarriage rates or increase live-birth rates in women undergoing in vitro fertilization and embryo transfer who had normal thyroid function and tested positive for thyroid autoantibodies 4.
Key points to consider:
- Levothyroxine and Synthroid are the same medication, with Synthroid being a brand name for levothyroxine
- No clinical difference between generic levothyroxine and brand-name Synthroid in terms of safety or effectiveness following pregnancy loss
- Maintaining consistent thyroid hormone levels is crucial, and switching between brands is not recommended
- Dosage adjustments may be necessary after a miscarriage, with thyroid function tests typically checked 4-6 weeks after the event
- Target TSH levels should be below 2.5 mIU/L for women trying to conceive
- Recent studies have found that levothyroxine treatment may not improve pregnancy outcomes in women with thyroid autoimmunity or hypothyroidism 3, 4.