If a woman is diagnosed with hypothyroidism prior to pregnancy, her thyroid medication should be adjusted so that the TSH level is no higher than 2.5 µU/ml prior to becoming pregnant.
If a woman is diagnosed as hypothyroid during pregnancy, she should be treated without delay, with the goal of restoring her thyroid levels to normal as quickly as possible. During the first trimester, the TSH should be maintained at less than 2.5 µU/ml (and less than 3.0 µU/ml in the second and third trimesters.) After initial diagnosis, thyroid function tests should be reevaluated within 30 to 40 days.
By the time a woman is four to six weeks pregnant, her dose of thyroid medication will usually need to be increased, potentially by as much as 30 to 50 percent.
A woman with thyroid autoimmunity (such as she has previously tested positive for thyroid antibodies) who has normal TSH levels in the early stages of her pregnancy is still at risk of becoming hypothyroid at any point in the. She should be monitored regularly through the pregnancy for elevated TSH.
Subclinical hypothyroidism – a TSH level above normal, with normal free T4 levels – is associated with negative health outcomes for both the mother and baby. Treatment of the mother has been shown to help ensure a healthier pregnancy. Treatment has not, however, been proven to affect the baby’s long-term neurological development. The experts believe that the potential benefits of treatment do outweigh any potential risks, however, and recommend treatment in women with subclinical hypothyroidism.
After childbirth, most women with hypothyroidism will need their dosage of thyroid hormone replacement reduced.
