Associations of Thyroid Function Tests with Lipid Levels and Adverse Pregnancy Outcomes During the First Trimester

Abstract

Objective

The present study aims to evaluate the relationship of thyroid function during the first trimester of pregnancy with lipid levels and pregnancy outcomes.

Methods

Women who delivered babies at the Shanghai General Hospital between March 2019 and December 2019 with a known pregnancy outcome and complete data were included in the present study (n = 1779). A retrospective cohort study of all subjects with available first-trimester thyroid function testing and lipid levels data was conducted, and the relationship of thyroid function with lipid levels and pregnancy outcomes was evaluated. The data were analyzed using the SPSS software for statistical correlation.

Results

The proportion of caesarean sections was higher in women with hypothyroxinemia (HIA) and hypothyroidism than in women with euthyroidism. Hypothyroidism was shown to be related with polyhydramnios, preterm labor and hypertriglyceridemia. HIA was correlated with increased rates of gestational diabetes mellitus (GDM), preeclampsia, gestational hypertension and hypertriglyceridemia. Compared with the euthyroidism group, the hypothyroidism group had a higher apolipoprotein A1 (Apo A1) level and apolipoprotein B level; the subclinical hypothyroidism group had a higher total cholesterol (TC) level and low-density lipoprotein cholesterol level; the HIA group had higher triglyceride, high-density lipoprotein cholesterol levels and lower TC, Apo A1 levels. TC levels were positively correlated with the thyroid-stimulating hormone level and negatively correlated with free thyroxine (FT4) level, and free triiodothyronine and FT4 levels were positively correlated with GDM occurrence.

Conclusion

Thyroid function in early pregnancy is associated with dyslipidemia and pregnancy outcomes; conventional screening of thyroid diseases in early pregnancy may help improve lipid levels and decrease adverse pregnancy outcomes.

Keywords:

• first trimester
• thyroid function tests
• adverse pregnancy outcome
• dyslipidemia

Abbreviations

PE, preeclampsia; HIA, hypothyroxinemia; SCH, subclinical hypothyroidism; GDM, gestational diabetes mellitus; TC, total cholesterol; LDL, low-density lipoprotein; HDL, high-density lipoprotein; TG, triglyceride; CS, cesarean section; PIH, pregnancy-induced hypertension; PTB, preterm labor; LBW, low birth weight; PPH, postpartum hemorrhage; TFT, thyroid function tests; ATA, American Thyroid Association; TSH, thyroid stimulating hormone; FT4, free thyroxine; FT3, free triiodothyronine; TPOAb, thyroid peroxidase antibody; Apo A1, apolipoprotein A1; Apo B, apolipoprotein B; Apo E, apolipoprotein E.

Ethics Statement

The study design was approved by the ethics committee of Shanghai General Hospital ([2021]036) and written informed consent was obtained from all subjects. This study was conducted in accordance with the declaration of Helsinki. The patients were selected from those who visited antenatal clinics of Shanghai General Hospital.

Acknowledgments

We thank the staff of laboratory and medical record section in Shanghai General Hospital for their help in technical assistance and information service. We are thankful to Xianming Xu Director for allowing us to carry out this work.

Disclosure

The authors declare no conflicts of interest in this work.

Additional information

Funding

There is no funding to report.