Changes in factor XIII level during pregnancy.

Area of Science:

• Obstetrics and Gynecology
• Hematology
• Clinical Chemistry

Background:

• Pregnancy induces significant haemostatic alterations, including rising clotting factors.
• Limited data exists on factor XIII (FXIII) level changes during pregnancy.

Purpose of the Study:

• To assess changes in plasma FXIII activity throughout normal pregnancy.
• To establish trimester-specific and immediate postnatal reference ranges for FXIII activity.

Main Methods:

• Cross-sectional study of 376 women with normal pregnancies.
• Plasma FXIII activity measured using a chromogenic assay on a CS-5100 analyser.
• Samples collected during the first, second, third trimesters, and immediate postnatal period, with a non-pregnant control group.

Main Results:

• Mean FXIII activity decreased progressively: first trimester (112 IU dL(-1)), second (96 IU dL(-1)), third (83 IU dL(-1)), and postnatal (90 IU dL(-1)).
• Significant reduction in mean FXIII activity observed in the second and third trimesters compared to the first trimester and controls (P < 0.0001).
• Postnatal FXIII levels were lower than the first trimester and control group.

Conclusions:

• This study provides essential reference ranges for FXIII activity during pregnancy and the early postpartum period.
• Normal pregnancy is associated with a significant decrease in FXIII activity, particularly in later trimesters.