TPO and hypothyroidism: As women with elevated anti-TPO antibodies are at increased risk for progression of hypothyroidism, if such women identified before conception require monitoring for hypothyroidism during pregnancy based on both guidelines, ATA recommends that serum TSH should be evaluated every 4 weeks during the first half of pregnancy and at least once between 26 and 32 m weeks gestation and Endocrine Society recommends that these women should be screened for serum TSH abnormalities before pregnancy, as well as during the first and second trimesters of pregnancy.