Clinical Predictors of Postpartum Persistent Hypothyroidism in Gestational Hypothyroidism: A Cohort Study

To determine whether gestational timing, biochemical severity, treatment response, or metabolic parameters predict postpartum persistent hypothyroidism and to evaluate the contribution of thyroid autoimmunity.

This single-center retrospective cohort study included pregnant women newly diagnosed with hypothyroidism in an internal medicine outpatient clinic. Recorded variables included demographic characteristics, gestational age at diagnosis, baseline thyroid-stimulating hormone (TSH) and free thyroxine (FT4) levels, follow-up thyroid function tests, fasting glucose, oral glucose tolerance test results, gestational diabetes diagnosis, and thyroid function at six weeks postpartum. Patients were categorized into early (≤13 weeks), mid (14-27 weeks), and late (≥28 weeks) diagnosis groups. Associations between gestational timing, treatment response, glycemic parameters, and postpartum persistent hypothyroidism were analyzed.

Fifty-eight women were included. Trimester-specific TSH targets were achieved in 32/58 (55.2%) at the first follow-up and 42/58 (72.4%) at the second follow-up. Early diagnosis, baseline TSH, levothyroxine dose, gestational timing, and glycemic indices were not associated with TSH normalization or postpartum persistent hypothyroidism (all p > 0.05). Postpartum persistent hypothyroidism developed in 14/58 women (24.1%). Thyroid autoantibody positivity was associated with persistence (p = 0.006) and remained independently associated with postpartum persistent hypothyroidism in multivariable analysis (odds ratio 9.78, 95% confidence interval 2.10-44.30; p = 0.020). TSH target achievement was not associated with reduced hyperglycemia.

Thyroid autoimmunity emerged as the principal determinant of postpartum persistent hypothyroidism, supporting antibody-based risk stratification. Gestational timing, treatment response, and metabolic indices were not significantly associated with postpartum thyroid outcomes.