Hypothyroidism and pregnancy: still a controversial issue

Area of Science:

• Obstetrics and Gynecology
• Endocrinology
• Reproductive Medicine

Background:

• Subclinical hypothyroidism (SCH) affects up to 15% of pregnancies, with ongoing debate on levothyroxine's benefits.
• Thyroid dysfunction during pregnancy requires careful management due to potential fetal and maternal risks.

Purpose of the Study:

• To assess fetal and maternal outcomes in pregnant women with pre-existing or newly diagnosed hypothyroidism.
• To investigate the impact of thyroid peroxidase (TPO)-antibodies and levothyroxine adequacy on pregnancy outcomes in SCH.

Main Methods:

• Retrospective and prospective cohort study including 393 pregnant women.
• Categorization into overt hypothyroidism (n=90) and SCH (n=303) groups.
• Analysis of pregnancy outcomes, TPO-antibody status, and levothyroxine substitution adequacy.

Main Results:

• SCH was more prevalent (77.1%), with 56% testing positive for TPO-antibodies.
• Levothyroxine substitution was suboptimal in most patients, particularly during the first trimester.
• TPO-antibody positivity was significantly associated with adverse fetal outcomes in SCH (p=0.018), independent of TSH levels or levothyroxine therapy.

Conclusions:

• TPO-antibody positivity appears to be a critical factor influencing pregnancy outcomes in SCH, surpassing TSH levels or levothyroxine treatment adequacy.
• Overt hypothyroidism was linked to increased pregnancy complications and higher rates of TPO-antibody positivity.
• Further research is warranted to elucidate the specific mechanisms by which TPO-antibodies affect pregnancy outcomes.