Frequency and outcomes of maternal thyroid function abnormalities in early pregnancy

Area of Science:

• Reproductive Epidemiology
• Endocrinology
• Developmental Neuroscience

Background:

• Thyroid hormones are critical for fetal brain development.
• Evidence is insufficient to recommend routine thyroid function testing during pregnancy.
• Maternal thyroid disease may impact fetal programming and neurodevelopment.

Purpose of the Study:

• Evaluate the frequency of undiagnosed thyroid dysfunction in pregnant women.
• Assess challenges in biochemical assessment of maternal thyroid function.
• Examine child neurodevelopmental outcomes following in utero thyroid dysfunction exposure.

Main Methods:

• Analysis of observational studies using Danish nationwide registers and the Danish National Birth Cohort.
• Review of dynamic changes in maternal thyroid-stimulating hormone (TSH) and free thyroxine (fT4) reference ranges in early pregnancy.
• Evaluation of child neurodevelopmental outcomes based on maternal thyroid dysfunction subtypes and severity.

Main Results:

• A high frequency of unidentified maternal thyroid function abnormalities was observed.
• Dynamic changes in TSH and fT4 reference ranges during the first trimester are detailed.
• Child neurodevelopmental outcomes are evaluated in relation to maternal thyroid dysfunction.

Conclusions:

• Undiagnosed maternal thyroid dysfunction is common and warrants further investigation.
• Understanding these abnormalities is crucial for optimizing pregnancy care and child development.
• Further research is needed to confirm the fetal programming hypothesis and its long-term effects.