AUTHOR=Yang Mengmeng , Sun Man , Jiang Chenyu , Wu Qianqian , Jiang Ying , Xu Jian , Luo Qiong 

TITLE=Thyroid hormones and carnitine in the second trimester negatively affect neonate birth weight: A prospective cohort study

JOURNAL=Frontiers in Endocrinology

VOLUME=Volume 14 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/endocrinology/articles/10.3389/fendo.2023.1080969

DOI=10.3389/fendo.2023.1080969

ISSN=1664-2392

ABSTRACT=Background: Maternal thyroid hormones and carnitine are reported to affect neonate birthweight during the second trimester, which is one of the most important markers for fetal growth and perinatal mortality and morbidity. Nevertheless, the effect of thyroid hormone and carnitine in the second trimester on birthweight has yet to be understood. 
Method: This was a prospective cohort study with 844 subjects enrolled during the first trimester. Thyroid hormones, free carnitine (C0), neonate birthweight, as well as other related clinical and metabolic data were collected and assessed. 
Results: Pre-pregnancy weight and body mass index (BMI), and neonate birthweight were significantly different among different free T4 (FT4) level groups. Maternal weight gain and neonate birthweight varied significantly when grouped by different TSH levels. There was a significantly positive correlation between C0 and thyroid stimulating hormone (TSH) (r=0.31), FT3 (r=0.37) and FT4 (r=0.59) (all P<0.001). In addition, a significantly negative influence was found between birthweight and TSH (r=-0.48, P=0.028), so as C0 (r=-0.55, P<0.001) and FT4 (r=-0.64, P<0.001). Further assessment detected a stronger combined effect of C0 and FT4 (P<0.001), and C0 and FT3 (P=0.022) on birthweight.
Conclusion: Maternal C0 and thyroid hormones are of great importance in neonate birthweight, and routine examination of C0 and thyroid hormones during the second trimester has a positive effect on the intervention of birthweight.