Biochemistry reference ranges in pregnancy

The diagrams below give an indication of the changes in reference ranges that are expected in pregnancy. Detailed method-specific ranges are not easily obtained; the diagrams use published data* and are not strictly comparable to BSUH ranges due to the use of different methodologies.
*Abbassi-Ghanavati M, Greer LG, Cunningham FG. Pregnancy and laboratory studies: a reference table for clinicians. Obstet Gynecol. 2006;114(6):1326–1331.
Trimester-specific ranges for current BSUH methods are available for thyroid function tests and oestradiol.


BSUH range for non-pregnant adult female.


Reference range quoted in reference paper for non-pregnant adult female.

Note that ranges are not strictly comparable due to the use of different methodologies.

For analytes marked *, BSUH units are IU/L, reference paper U/L.

1st, 2nd and 3rd

Ranges quoted in the reference paper for the three trimesters of pregnancy.


U&E, amylase, uric acid, CRP

LFT profile, CK, LDH

Bone profile, magnesium, PTH, ACE

See LFT profile for albumin and ALP

Cortisol, sex hormones, AFP

Reference data for prolactin and AFP are plotted on secondary axes (in red) as they are in different units to those used by BSUH. Trimester-specific ranges are available for current BSUH thyroid function tests and oestradiol methods.


BSUH quotes lipid targets rather than reference ranges:

Cholesterol < 5.0 mmol/L

HDL >1.0 mmol/L

LDL < 3.0 mmol/L

Triglycerides < 2.0 mmol/L