Association of Subclinical Hypothyroidism with Bad Obstetric History: A Review

Abstract

Objectives: To review the association between subclinical hypothyroidism (SCH) and bad obstetric history (BOH), focusing on prevalence, outcomes, and management. Study Design and Setting: Narrative review of published studies on SCH in women with BOH, retrieved from major medical databases. Methodology: Relevant literature was searched using keywords related to SCH, pregnancy, and obstetric outcomes. Data were synthesized on epidemiology, diagnostic criteria, risk factors, pregnancy outcomes, and treatment. Results: SCH affects 2–19% of pregnancies, with prevalence influenced by iodine intake, population, and diagnostic thresholds. SCH is linked to recurrent miscarriage, preeclampsia, gestational diabetes, intrauterine growth restriction, stillbirth, and low birth weight. The risk is higher among thyroid peroxidase antibody–positive women. Evidence suggests levothyroxine therapy reduces miscarriage and neonatal complications, though its effect on broader maternal outcomes remains debated. Despite growing evidence, universal screening and treatment for SCH are not consistently practiced, especially in resource-limited settings. Conclusions: SCH is a significant but underdiagnosed contributor to adverse obstetric outcomes, particularly in women with BOH. Early detection and appropriate management with levothyroxine may improve maternal and fetal outcomes. Standardized screening guidelines and further large-scale studies are needed to integrate SCH management into routine obstetric care.