Beyond iodine nutrition: socioeconomic patterns independently drive thyroid disease risk in pregnant women in Xinjiang.

OBJECTIVE

To investigate the impact of distinct socioeconomic status (SES) patterns on the risk of thyroid diseases in pregnant women against the background of adequate iodine nutrition.

METHODS

A cross-sectional study was conducted in Xinjiang from 2021 to 2022, enrolling 1,166 pregnant women. Fasting venous blood and urine samples were collected to assess thyroid function and iodine nutritional indicators. Long-term and short-term iodine intake were evaluated using a food frequency questionnaire and a 3-day 24-h dietary recall, respectively. Latent class analysis (LCA) was used to identify socioeconomic-environmental patterns based on region, income, education, occupation, and passive smoking status. Multivariable regression models were constructed to analyze the association between SES patterns and thyroid outcomes, adjusting for maternal and environmental covariates. Mediation analysis models were used to assess the mediating effect of iodine nutritional indicators.

RESULTS

Three SES patterns were identified: Pattern A (Northern Xinjiang-Housewife-dominant Low SES, 37.14%), Pattern B (Southern Xinjiang-Housewife-dominant Low-to-Middle SES, 41.60%), and Pattern C (Highly Educated-Professional Women-High SES, 21.27%). Compared with Pattern A, Pattern C was significantly associated with lower TSH levels (β = -0.17, 95% CI: -0.32 - -0.03, p = 0.019). In the logistic regression models, Pattern B was significantly associated with lower odds of thyroid nodules compared with Pattern A (OR = 0.32, 95% CI: 0.14-0.74, p = 0.008). No statistically significant associations were observed between SES patterns and other thyroid disease outcomes after adjustment. Mediation analysis suggested that although dietary iodine intake and urinary iodine-to-creatinine ratio differed across SES patterns, these iodine nutritional indicators did not show statistically significant mediation in the associations between SES patterns and thyroid-related outcomes (p > 0.05).

CONCLUSION

Against the overall background of adequate iodine nutrition, differences in socioeconomic patterns were independently associated with thyroid disease outcomes in pregnant women in Xinjiang, and this influence is not dependent on differences in iodine intake. This study suggests that prevention and control strategies for perinatal thyroid diseases should extend beyond single nutritional interventions towards psychological support and comprehensive environmental management targeting specific social roles.