Detection of thyroid dysfunction in early pregnancy: Universal screening or targeted high-risk case finding?

Area of Science:

• Obstetrics and Gynecology
• Endocrinology
• Reproductive Health

Background:

• Maternal subclinical hypothyroidism is linked to adverse pregnancy outcomes.
• Current guidelines suggest targeted thyroid function screening for high-risk pregnancies, not universal screening.
• High-risk criteria include personal or family history of thyroid or autoimmune disorders.

Purpose of the Study:

• To evaluate the effectiveness of a targeted, high-risk case-finding strategy for identifying thyroid dysfunction in early pregnancy.
• To determine if focusing on high-risk individuals adequately detects thyroid dysfunction.

Main Methods:

• A single-center prospective cohort study of 1560 pregnant women in their first antenatal visit (median 9 weeks gestation).
• Thyroid-stimulating hormone (TSH), free T4, and free T3 levels were analyzed.
• Thyroperoxidase antibodies were tested in 85% of participants.
• A high-risk group (26.5%) was defined by personal/family history of thyroid or autoimmune disorders.

Main Results:

• Twenty-six percent of women were classified as high-risk.
• The prevalence of elevated TSH (>4.2 mIU/liter) was 6.8% in the high-risk group versus 1% in the low-risk group (RR 6.5, P < 0.0001).
• Personal history of thyroid disease, other autoimmune disorders, thyroperoxidase antibodies, and family history of thyroid disorders were associated with increased TSH levels.
• Crucially, 30% of women with elevated TSH were identified in the low-risk group.

Conclusions:

• Relying solely on a targeted high-risk screening approach for thyroid dysfunction in pregnancy may miss a significant proportion (approximately one-third) of affected women.
• This highlights potential limitations in current guidelines for identifying hypothyroidism during early pregnancy.