Associations Between Maternal Thyroid Function and Birth Outcomes in Chinese Mother-Child Dyads: A Retrospective Cohort Study.

Geng-Dong Chen,Xia-Fen Lu,Dong-Xin Lin,Ting-Ting Pang,Zi-Xing Zhou,Zheng-Ping Liu,Xiu-Yin Shen,Peng-Sheng Li,De-Mei Lu,Jie Yang,Shao-Xin Ye,Da-Zhi Fan

doi:10.3389/fendo.2020.611071

Geng-Dong Chen, Xia-Fen Lu + Show 10 more

Open Access

https://doi.org/10.3389/fendo.2020.611071

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Abstract

ObjectiveAlthough research suggests a close association between maternal thyroid function and birth outcomes, no clear conclusion has been reached. We aimed to explore this potential association in a retrospective cohort study.MethodsThis study included 8985 mother–child dyads. The maternal serum free tetraiodothyronine (FT4), thyroid-stimulating hormone (TSH), and thyroid peroxidase antibody (TPO Ab) concentrations and birth outcome data were reviewed from medical records. Subjects with TPO Ab concentrations of >34 and ≤34 IU/ml were classified into the TPO Ab positivity (+) and TPO Ab negativity (−) groups, respectively.ResultsCompared with subjects in the normal group (0.1 ≤ TSH < 2.5 mIU/L and TPO Ab−), those with TSH concentrations of 2.5–4.0 mIU/L and TPO Ab− had a 0.65-fold lower risk of low birth weight (LBW). In contrast, those with TSH concentrations of >4.0 mIU/L, regardless of the TPO Ab status, had a 2.01-fold increased risk of LBW. Subclinical hypothyroidism, regardless of the TPO Ab status, was associated with a 1.94-fold higher risk of LBW when compared with that in subjects with euthyroidism and TPO Ab−. No other significant associations were observed.ConclusionA maternal TSH concentration of 2.5–4.0 mIU/L was associated with a lower risk of LBW when combined with TPO Ab−, whereas subjects with a TSH concentration of >4.0 mIU/L had an increased risk of LBW. Subclinical hypothyroidism appears to be associated with a higher risk of LBW.

Highlights

Euthyroidism, or normal thyroid function, is an important component of human health
We aimed to investigate full-scale associations of thyroid indicators and clinical thyroid statuses with birth outcomes in a large population of Chinese mother–child dyads
Mothers aged 18–45 years who delivered their babies at the center and underwent thyroid function testing (FT4, thyroid-stimulating hormone (TSH), and TPO Ab) during pregnancy were included in this study

Summary

Introduction

Euthyroidism, or normal thyroid function, is an important component of human health. The circulating concentrations of thyroid hormones, including free thyroxine (FT4) and thyroid-stimulating hormone (TSH), are commonly used to indicate thyroid function, whereas a concentration of antithyroperoxidase antibody (TPO Ab) that exceeds a certain cutoff threshold (according to measurement kits) for TPO Ab positivity (TPO Ab+) is an important factor in the diagnosis of thyroid autoimmunity. That study excluded TPO Ab+ subjects, and the influence of the TPO Ab status could not be determined [12] In another meta-analysis of 19 cohorts involving 47045 pregnant women, subclinical hypothyroidism, isolated hypothyroxinemia, and TPO Ab+ were associated with a high risk of preterm birth (PB). Several studies found that TSH concentrations between 2.5 and 4.0 mIU/L or >4.0 mIU/L might exert different influences on pregnancy and birth outcomes, leading to the suggestion of a TSH concentration of 4.0 mIU/L as a potential new cutoff point for determining the thyroid function status [10, 11]. The evidence from these former studies encourages further exploration based on full-scale thyroid indicators in well-designed studies

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