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

OBJECTIVE

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

MATERIAL AND

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.