Management of Hypothyroidism in Pregnancy

Introduction to Hypothyroidism Management

Pregnant women with hypothyroidism require immediate levothyroxine treatment with aggressive dose titration to maintain TSH <2.5 mIU/L in the first trimester, as untreated or inadequately treated maternal hypothyroidism significantly increases risks of miscarriage, preeclampsia, preterm birth, low birth weight, placental abruption, fetal death, and permanent neurocognitive impairment in offspring, according to the American Academy of Family Physicians 1, 2

Confirm adequate treatment before attempting conception, as women adequately treated before pregnancy have no increased risk of perinatal morbidity, as recommended by the American Academy of Family Physicians 1
Educate patients that levothyroxine requirements will increase by 25-50% during pregnancy, as stated by the American Academy of Family Physicians 2

Do not delay treatment waiting for repeat testing, as first-trimester hypothyroidism is associated with cognitive impairment in children, according to the American Academy of Family Physicians 1, 2

Adjust levothyroxine by 12.5-25 mcg increments based on TSH results, as recommended by the American Academy of Family Physicians 2
Most women require 25-50% dose increase above pre-pregnancy levels, according to the American Academy of Family Physicians 2
Maintain free T4 in the high-normal range throughout pregnancy, as stated by the American Academy of Family Physicians 2

First-trimester hypothyroidism specifically causes cognitive impairment in children, according to the American Academy of Family Physicians 1, 2
Clinical and subclinical hypothyroidism increase risk of preterm birth, low birth weight, placental abruption, and fetal death, as reported by the American Academy of Family Physicians 1, 2

Do not wait for symptoms to develop before checking TSH, as fetal harm occurs before maternal symptoms appear, as recommended by the American Academy of Family Physicians 2
Avoid targeting TSH >2.5 mIU/L in the first trimester, as even subclinical hypothyroidism associates with adverse pregnancy outcomes, according to the American Academy of Family Physicians 2