Clinical Chemistry in Pregnancy


During pregnancy, a woman undergoes a multitude of normal physiochemical changes that are specific to pregnancy and with increasing frequency, challenged with pregnancy‐related conditions. Additionally, there are a number of problems affecting the unborn fetus that, in turn, affect normal maternal biochemistry, endocrinology and physiology. Furthermore, normal biochemical, hormonal and clinically relevant measurements for the nonpregnant state often no longer apply to the pregnant woman. This makes clinical laboratory measurement difficult and normal clinical diagnosis using nonpregnant values potentially dangerous, with inappropriate treatment (when it is not required) and no treatment (when it is required) being offered. Problems within early pregnancy, for example, spontaneous and recurrent miscarriage, thus become very complicated to predict or treat. Therefore, reexamining what clinical chemical tests are available and what is just emerging from the experimental laboratory (and thus becoming available in the standard clinical laboratory), should inform the unwary clinician.

Key Concepts:

  • ‘Normal’ pregnancy biochemical marker (Biomarker) concentrations fluctuate throughout pregnancy.

  • No single maternal biomarker can be used to predict gestational disease.

  • Both the concentrations of urinary, serum, plasma, salivary and amniotic fluid biomarkers and the timing of clinical sampling are critical in disease diagnosis.

  • Many new biomarkers are emerging, which may help aid the prediction/diagnosis of pregnancy‐related conditions.

Keywords: pregnancy; clinical chemistry; human chorionic gonadotrophin; human placental lactogen; oestrogen; progesterone; anandamide; endocannabinoid; PAPP‐A; alpha fetoprotein

Figure 1.

Biomarkers involved in the maintenance of early pregnancy. The diagram shows an implanted embryo (approximately 14 days after conception) and the processes necessary for the maintenance of an early pregnancy together with the important maternal biomarkers used to determine the course of successful and abnormal pregnancy. hPL, human placental lactogen; hCG, human chorionic gonadotrophin; AFP, alpha fetoprotein. Local anandamide concentrations are regulated by fatty acid amide hydrolase (FAAH) activity, which in turn is regulated by progesterone action. All of the indicated biomarkers are measurable in maternal plasma and serum, except FAAH, which can be measured in peripheral blood mononuclear cells. The image is a modification of the superb original figure produced by Norwitz E, Schust DJ and Fisher SJ (2001) Implantation and survival of early pregnancy. New England Journal of Medicine 345: 1400–1408. © 2001. Massachusetts Medical Society. Reprinted with permission from Massachusetts Medical Society.



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Further Reading

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Taylor, Anthony H, Melford, Sarah E, and Konje, Justin C(Jan 2013) Clinical Chemistry in Pregnancy. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1002/9780470015902.a0023397]