Association between sFer Levels in Early Pregnancy and Thyroid Function in Chinese Population

Backgrounds: : The relationship of Iron deficiency and thyroid hormone have been researched a lot among pregnant or other healthy population. However, invisible iron deficiency, namely shortage of sFer level, has been barely investigated among Chinese pregnant women. This study aimed to explore the effects of sFer status on thyroid function in a population-based upper first-class hospital. Methods A total of 781 singleton pregnant women of gestation in Shanghai General Hospital took part in this retrospective cohort study. The participants were divided into four groups by quartiles of serum ferritin levels (Q1–4). Binary logistic regressions were used to examine the strength of association between the different traits and the serum ferrin (sFer) quartiles separately, where Q1 (lowest ferritin quartile) was taken as the base reference. One-way ANOVA was adopted to compare the averages of the different variables across Sfer quartiles. Categorical measures were compared by Fisher exact test or chi-square test. Results As the sFer concentration rises, incidence of premature birth (15.8%vs 12.3% vs 9.20% vs 6.20% p = 0.016) as well as threatened miscarriage (14.8% vs 7.2% vs 8.70% vs 6.70% p = 0.021)presented a downward trend. Compared with the other sFer group, subjects of the low sFer group were older, were more often found to have lower serum γT3 and FT4 levels in early pregnancy but not in middle pregnancy. Conclusions The correction of invisible iron deficiency with inadequate sFer status prior to pregnancy or during early pregnancy is imperative, not only to prevent anemia, but also for maintaining optimum thyroid function and normal fetal development. For clinicians, sFer status of pregnant women should be attached great importance apart from attention to iron level.