Specific Aims:

1. To determine the levels of maternal thyroid function tests which result in impaired development of the offspring.

a. To determine the levels of TSH, free thyroxine, thyroglobulin, and thyroid peroxidase antibody in the sera of pregnant women at known times in the pregnancy

b. To compare maternal thyroid function with the neurodevelopment of the child at age 8 years, and determine the association between maternal thyroid levels and specific effects in domains of IQ, attention, behavior, speech and language skills, social cognition, gender behavior, executive function, and manual dexterity in the ALSPAC dataset, controlling for potential confounders such as maternal smoking status and socioeconomic status.

c. To determine which maternal factors (e.g. age, antibody status) and offspring factors (e.g. gender) modify the relationship between trimester-specific thyroid status and development of the offspring.

2. To determine the levels of maternal thyroid function tests which result in fetal demise.

3. To develop trimester-specific normative ranges for thyroid hormone levels during pregnancy, based on the relationship with impaired development and fetal loss.