Levothyroxine while pregnant
Pro Research Analysisby 
Searched over 200M research papers
Levothyroxine Use During Pregnancy: Impacts and Recommendations
Introduction to Levothyroxine and Pregnancy
Levothyroxine (LT4) is a synthetic form of the thyroid hormone thyroxine, commonly prescribed to manage hypothyroidism. During pregnancy, maintaining optimal thyroid function is crucial for both maternal and fetal health. This article synthesizes recent research on the effects of LT4 supplementation in pregnant women, particularly those with subclinical hypothyroidism (SCH) and thyroid autoimmunity (TAI).
Levothyroxine and Subclinical Hypothyroidism in Pregnancy
Improved Pregnancy Outcomes with LT4
Several studies have shown that LT4 supplementation can significantly improve pregnancy outcomes in women with SCH. For instance, a meta-analysis of randomized controlled trials (RCTs) found that LT4 treatment significantly reduced miscarriage rates in women undergoing assisted reproduction technologies (ART) . Another study confirmed that LT4 supplementation decreased the risk of pregnancy loss and preterm birth in women with SCH and/or TAI.
No Significant Impact on Some Outcomes
However, not all studies agree on the benefits of LT4. A comprehensive review found no significant differences in primary outcomes such as preterm delivery, miscarriage, gestational hypertension, and preeclampsia between LT4-treated and untreated groups. This suggests that while LT4 may benefit certain aspects of pregnancy, its overall impact on all pregnancy outcomes remains inconclusive.
Levothyroxine and Thyroid Autoimmunity
Benefits in Reducing Pregnancy Loss
Women with thyroid autoimmunity, particularly those positive for thyroid peroxidase antibodies (TPOAb), are at increased risk of adverse pregnancy outcomes. Research indicates that LT4 supplementation can reduce the risk of pregnancy loss in these women . A meta-analysis of RCTs showed that LT4 treatment significantly decreased the risk of pregnancy loss and preterm birth in women with TAI.
Mixed Results on Live Birth Rates
Despite these benefits, the impact of LT4 on live birth rates is less clear. A large-scale study found no significant difference in live birth rates between LT4-treated and placebo groups among euthyroid women with TPOAb. Similarly, another meta-analysis concluded that LT4 did not significantly improve live birth rates or reduce miscarriage rates in women with thyroid autoimmunity.
Levothyroxine in Assisted Reproduction Technologies
Enhanced Outcomes in ART
In the context of ART, LT4 supplementation has shown promising results. A systematic review and meta-analysis reported that LT4 treatment significantly increased delivery rates and reduced miscarriage rates in women with SCH undergoing ART. This suggests that LT4 may be particularly beneficial for women undergoing fertility treatments.
Need for Further Research
Despite these findings, more research is needed to fully understand the benefits of LT4 in ART settings. Current data are limited, and further studies are required to confirm these results and explore the mechanisms behind LT4's effects on pregnancy outcomes in ART .
Conclusion
The use of levothyroxine during pregnancy, particularly in women with subclinical hypothyroidism and thyroid autoimmunity, shows potential benefits in reducing miscarriage and preterm birth rates. However, its impact on other pregnancy outcomes, such as live birth rates and gestational complications, remains uncertain. While LT4 supplementation is recommended for certain groups, further research is essential to establish comprehensive guidelines and optimize treatment protocols for pregnant women with thyroid disorders.
Sources and full results
Most relevant research papers on this topic