THYROID FUNCTION IN PREGNANCY: AN AUDIT
B Vaidya1, M Bilous1, RS Hutchinson2 & RW Bilous1
Background and Aims: Recent studies have suggested that maternal thyroid dysfunction, particularly in early pregnancy, may have a detrimental effect on the neuropsychological development of offspring. In the light of these studies a local guideline was drawn which recommended screening thyroid function at booking in all pregnant women with a personal or family history of thyroid disease. The aims of this study were to assess adherence to this guideline, and to test its efficacy in preventing abnormal thyroid function in early pregnancy.
Material and Methods: All new pregnant women, who were booked at the antenatal clinic at the James Cook University Hospital in the year 2000 were included in the study. Data were collected from the computerised antenatal and central laboratory databases, and from case-notes of the combined antenatal endocrine clinic.
Results: There were 4083 new bookings at the antenatal clinic in that year. Of these, 65 (1.6%) had known thyroid disease, and further 486 (11.9%) had a family history of thyroid disease. It was found that, at booking, thyroid function was screened in 60 (92.3%) patients with known thyroid disease, and in 38 (7.8%) patients with only family history. One-third (21 out of 65) of the patients with known thyroid disease had either high thyrotrophin (TSH) level with/without low free thyroxine (FT4) (n=17, 26.2%) or suppressed TSH with raised FT4 (n=4, 6.2%). Two (5.2%) of the 38 patients with family history who were not known to have thyroid disease had high TSH levels.
Conclusions: A large number of women, who are at risk of thyroid disease, are not being screened for thyroid dysfunction during pregnancy. Many pregnant women with known thyroid disease have abnormal thyroid function at booking, which highlights the importance of pre-pregnancy counselling and early thyroid function tests in these patients.