Spontaneous normalisation of mildly abnormal thyroid function in pregnancy: a systematic review and meta-analysis of pooled proportions
Year: 2026
Type: preprint
Abstract: Mildly abnormal thyroid function - subclinical hypothyroidism (SCH) and isolated maternal hypothyroxinaemia (IMH) - is commonly detected on a single thyroid function test in early pregnancy, and levothyroxine is frequently initiated without confirmatory retesting. Because thyroid physiology changes substantially across gestation and human chorionic gonadotropin suppresses TSH in the first trimester, an appreciable proportion of these abnormalities may resolve without treatment. The size of that proportion has not been synthesised. This systematic review will pool the proportion of untreated pregnant women with a mildly abnormal index thyroid function test whose repeat test during the same pregnancy falls within the applicable reference range. Secondary analyses will compare SCH with IMH, examine variation by index TSH stratum, thyroid peroxidase antibody (TPOAb) status, gestational age at index testing, retest interval and reference range used, and estimate the proportion progressing to overt hypothyroidism without treatment. The findings bear directly on whether a single abnormal antenatal thyroid result should trigger treatment or confirmatory retesting, and therefore on the risk of overdiagnosis and overtreatment in pregnancy.
Language: English
Subfield: Endocrinology, Diabetes and Metabolism
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W7204059540