Objective: To establish gestation-specific reference intervals for thyroid function tests in normal singleton pregnancy.
Study design: Cross-sectional observational study performed in the Obstetric and Gynaecology department, West Middlesex University Hospital. A single blood sample from 335 pregnant women at various gestations of pregnancy was analysed for thyroid function. FT4, fT3, TSH values at each gestation of pregnancy were calculated.
Results: From the fT3, fT4 and TSH results, a 95% reference interval was calculated for each hormone for each week of pregnancy.
Conclusion: We calculated gestation-specific reference intervals for thyroid function tests throughout pregnancy to facilitate clinical management of thyroid disease in pregnancy.