Why Should Pregnant Patients Who Have Hypothyroidism Continue to Take

Why should pregnant patients who have hypothyroidism continue to take thyroid replacement drugs throughout pregnancy?

A) These drugs are pregnancy category A and have no side effects.
B) Without continuing thyroid replacement drugs, the pregnancy may not continue.
C) Pregnancy is a high metabolism condition and less drug is needed but should still be taken.
D) The fetus produces thyroid hormones that help supplement the pregnant woman's hormone level, but minimal replacement is needed during pregnancy.