Table 2.
Distribution of lower or higher thyroid function tests in pregnant women as compared to the normal ranges of nonpregnant women.
| Thyroid hormone | 1st trimester n (%) |
2nd trimester n (%) |
3rd trimester n (%) |
|---|---|---|---|
| FT4 (11.0–22.0 pmol/L)* | |||
| Low value | 53 (20.9) | 67 (26.4) | 60 (23.6) |
| High value | 5 (2.0) | 0 | 0 |
| FT3 (2.5–5.8 pmol/L) | |||
| Low value | 7 (2.8) | 0 | 0 |
| High value | 18 (7.1) | 13 (5.1) | 22 (8.7) |
| TSH (0.3–4.0 mIU/L) | |||
| Low value | 37 (14.6) | 7 (2.8) | 0 |
| High value | 5 (2.0) | 6 (2.4) | 14 (5.5) |
*Normal range derived as 95% confidence interval.