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REMEDY : BNSSG referral pathways

Thyroid Function Tests and Pregnancy

Checked: 11-02-2019 by Rob.Adams Next Review: 11-02-2020


There is no national screening programme for thyroid function testing in women who are planning pregnancy.

Women who are found to have hypothyroidism should be advised to delay conception until TSH has been stabilised on levothyroxine.

There are pan- Bristol guidelines produced by local clinical biochemists and endocrinologists which cover the following areas:

When to consider testing TSH in women who are planning pregnancy without known thyroid disease.

When to treat hypothyroidism (primary or subclinical) in women planning pregnancy.

The normal reference ranges in pregnancy for women without any pre-existing thyroid condition.

Treatment target ranges for women with primary or subclinical hypothyroidism on levothyroxine.


Clinical Knowledge Summaries also has advice on management of hypothyroidism both pre-conception and during pregnancy.


Pregnant women with hypothyroidism should be referred to their local antenatal clinic.

If advice is required on starting or adjusting levothyroxine doses in pregnancy then contact your local endocrinology department via switch.