The purpose of this study is to determine whether treatment of thyroid disease during pregnancy decrease the incidence of adverse outcome, and to compare the impact of Universal Screening versus case Finding strategy in detecting thyroid dysfunction

Thyroid disease during pregnancy has been associated with multiple adverse outcomes including miscarriage, preterm delivery, postpartum thyroiditis and decreased IQ in the offspring. Whether or not all women should be screened for thyroid disease during pregnancy (Universal Screening), screening should be confined to women at high risk for thyroid disease (Case Finding), or no screening should occur is controversial. For this purpose, pregnant women in the first trimester are randomly assigned to the Screening group or Case finding group. All women in the Screening group and high-risk women in the Case Finding group are immediately tested for FT4, TSH and TPO antibodies. Low-risk women in the Case Finding group have their sera tested postpartum. levothyroxine or PTU are given in hypothyroid and hyperthyroid women respectively. Outcome Measure: total number of adverse events occurring during pregnancy and in the neonatal period controlling for clustering of outcomes within women.

Inclusion Criteria:

• Pregnant women
• Within 11 week of gestation

Exclusion Criteria:

• Already known thyroid disease