Calculated reference interval (mg/L) Calculated reference interval (mg/L) Suggested reference interval (mg/L)
Trimester
Upper limit (90% CI) Lower limit (90% CI)
First
21.48 (18.64-24.74) 0.46 (0.38-0.57)
<18
Second
20.46 (17.91-23.38) 0.73 (0.63-0.84)
Third
18.90 (16.45-21.73) 0.75 (0.67-0.83)