Vitamin D categories and postpartum thyroid function in women with hypothyroidism

Area of Science:

• Endocrinology
• Reproductive Medicine
• Nutritional Science

Background:

• Postpartum thyroid dysfunction affects a significant number of women with pre-existing overt hypothyroidism (OH) or subclinical hypothyroidism (SCH).
• The role of vitamin D in modulating thyroid function during the critical postpartum period requires further elucidation.

Purpose of the Study:

• To identify factors influencing postpartum thyroid function in women with OH/SCH.
• To investigate the impact of vitamin D status on postpartum thyroid outcomes.

Main Methods:

• Longitudinal monitoring of thyroid hormones, autoantibodies, and serum 25-hydroxyvitamin D (25OHD) from pregnancy to 12 months postpartum.
• Statistical analyses including logistic regression, Cox regression, and Latent Class Growth Model to assess prognostic factors and vitamin D trajectories.

Main Results:

• 36.5% of women showed improved thyroid function, 37.3% had persistent hypothyroidism, and 26.2% developed new thyroid dysfunction postpartum.
• Vitamin D sufficiency, positive thyroid peroxidase antibodies (TPOAb), and positive thyroglobulin antibodies (TgAb) in early pregnancy were independent predictors of postpartum thyroid function.
• Sufficient vitamin D independently predicted improved thyroid function and offered protection against new dysfunction in TPOAb-positive women.

Conclusions:

• Optimizing vitamin D nutrition during pregnancy and the postpartum period may positively influence thyroid function recovery.
• Vitamin D sufficiency appears to be a key modifiable factor for improving postpartum thyroid health in at-risk women.