Table 1.

Central 95% reference intervals, 90% confidence intervals and the confidence ratios for TSH&FT4 in various gestational groups.

Test (Unit of measure)	1st Trimester (n = 136)	2nd Trimester (n = 146)	3rd Trimester (n = 132)
FT4 (pmol/L) Reference Interval	11.73 – 20.39	9.25 – 17.22	8.71 – 15.26
− 90% CI for lower limit	11.27 – 12.35	8.76 – 10.0	7.89 – 9.52
− 90% CI for upper Limit	19.12 – 22.16	16.06 – 18.27	14.49 – 15.54
-Confidence ratio	0.24	0.25	0.20
TSH (mIU/L) Reference Interval	0.094 – 3.33	0.052 – 4.56	0.44 – 4.75
− 90% CI for lower limit	0.012 – 0.13	0.005 – 0.54	0.32 – 0.62
− 90% CI for upper Limit	2.60 – 3.71	3.94 – 5.46	4.16 – 5.63
-Confidence ratio	0.19	0.20	0.21