Hyperthyroidism
40
Table 4. Risks and Guidance for Treating Graves' Disease
During Pregnancy
Graves' disease
treatment option Risks Guidance
ATDs Congenital
anomalies (more
severe with MMI
than PTU)
• Discuss ATD risks in pregnancy
through shared decision-making in
preconception.
• Confirm pregnancy promptly if
suspected.
• Consider discontinuing ATDs in
pregnant women at low risk of disease
relapse during the first trimester.
• If PTU is available, consider switching
from MMI to PTU as soon as pregnancy
is confirmed, using a dosing ratio of 1:20
(MMI to PTU).
• If ATD use continues to be needed
during pregnancy, treat with PTU (if
available) until 16 weeks gestation. The
choice for a preferred ATD after 16
weeks gestation is unknown.
Fetal goiter • Monitor maternal thyroid function
every 2–4 weeks, aiming for FT4
concentration at or slightly above the
upper third of the reference interval.
• Fetal ultrasound monitoring should be
performed monthly starting at 18–20
weeks gestation if the mother uses ATDs
during pregnancy, monitoring frequency
can be reduced for low dose ATD on a
case-by-case basis.
• If ATDs can be discontinued in
pregnancy, then the maternal TRAb
and/or TSI concentration can be
checked
a
and subsequent fetal ultrasound
follow-up can be continued if the result
remains >3 times the upper limit of
normal after approximately 18–20 weeks
gestation.
Fetal and neonatal
thyroid dysfunction
• Same guidance as for "Fetal goiter" above.
• Consider discontinuing ATD treatment
by 30–34 weeks gestation if appropriate.
