Low birth weight is not associated with thyroid autoimmunity: a population-based twin study

Area of Science:

• Endocrinology
• Genetics
• Immunology

Background:

• Low birth weight has been suggested as a risk factor for developing thyroid autoantibodies in adulthood.
• Potential genetic or environmental factors could confound the association between birth weight and thyroid autoimmunity.
• Twin studies can help minimize confounding factors to investigate this relationship.

Purpose of the Study:

• To investigate the impact of low birth weight on thyroid autoimmunity.
• To determine if within-twin differences in birth weight correlate with thyroid peroxidase antibodies (TPOAb) and thyroglobulin antibodies (TgAb) levels.
• To assess the role of birth weight in the etiology of thyroid autoimmunity.

Main Methods:

• Study included 1024 euthyroid individuals from 512 same-sex twin pairs.
• Birth weight data was obtained from historical midwife protocols.
• Serum concentrations of TPOAb and TgAb were measured using fluoroimmunometric assays.

Main Results:

• No statistically significant association was found between birth weight and serum concentrations of TPOAb or TgAb.
• Analysis of twin pairs with significant birth weight differences (≥500g or born ≥4 weeks preterm) yielded similar results.
• Controlling for confounders like sex, zygosity, gestational age, TSH, and smoking did not alter the non-significant findings.

Conclusions:

• Low birth weight is not an evident etiological factor in the development of thyroid autoimmunity.
• The study suggests that other factors likely contribute to the development of thyroid autoimmunity.