Maternal smoking and high BMI disrupt thyroid gland development

Area of Science:

• Endocrinology
• Developmental Biology
• Public Health

Background:

• Maternal lifestyle factors like smoking and obesity pose risks for adult diseases.
• The fetal thyroid gland is crucial for metabolic rate, cardiac output, and brain development.
• Altered fetal thyroid function may predispose individuals to later-life diseases.

Purpose of the Study:

• To investigate the impact of maternal smoking and high body weight on human fetal thyroid function.
• To examine these effects during the second trimester of pregnancy.

Main Methods:

• Collected thyroid glands and plasma from second-trimester fetuses.
• Measured plasma thyroid hormones (T3, T4) and TSH.
• Analyzed thyroid histology, gene expression (developmental, functional, apoptotic, detoxification markers), and correlated with maternal smoking and BMI using regression models.

Main Results:

• Maternal smoking altered fetal plasma T4 and TSH levels, reduced thyroid GATA6 and NKX2-1 transcripts, and affected ESR2 and AHR transcript development.
• High maternal BMI (>25) increased fetal thyroid weight, plasma TSH, and caused abnormal histology in female fetuses.
• Normal AHR and ESR1 transcript changes were abolished in fetuses of mothers with BMI > 25.

Conclusions:

• Maternal smoking and high BMI disturb fetal thyroid development and endocrine function in a sex-specific manner.
• These findings suggest that altered fetal thyroid development contributes to the predisposition of post-natal diseases.
• Highlights the importance of maternal health for fetal development and long-term health outcomes.