Conclusion
In conclusion, this study provides the data on iron nutritional status and thyroid hormones of pregnant second-trimester women in Pingguo County. During the second trimester of pregnancy, ID may result in lower FT4 and FT3 and higher TSH, and these findings are consistent with the earlier reports. Indeed, SF is positively correlated with FT3 and FT4 levels, and negatively correlated with TSH levels. Hb may also play a certain role in affecting the thyroid function. Although the specific mechanism is still unclear, the correlation between iron nutrition and thyroid hormone should not be underestimated. Involving two common endocrine diseases in pregnancy, the relationship between ID and thyroid hormone, the molecular mechanisms involved, and the disease consequences deserve further investigation. From the perspective of maintaining maternal health and offspring’s health, we recommend that ID should be estimated and treated to prevent thyroid dysfunction during the second trimester of pregnancy or even earlier. In addition, it also provides a new idea and reference for improving the quality of life of pregnant women and their offspring.