Summary
A longitudinal study of 21 pregnant women has been undertaken using a variety of factor
VII assays, including factor VIIa, to investigate the increase of factor VIIc. All
assays demonstrated significant rises (p <0.001), most marked for factor VIIa (82%)
and factor VIIc rabbit (81%). Smaller rises were seen for factor VIIc bovine (50%)
and VII antigen (40%). Three indirect measures of activity state, factor VIIc rabbit:antigen,
bovine:antigen and bovine:rabbit, provided conflicting data. Factor VIIa:antigen showed
a significant increase of 36% (p <0.001). Within individual pregnancies the change
in factor VIIc rabbit and antigen correlated with maternal weight gain (p <0.05).
Two activity state measures, bovine:rabbit and bovine:antigen, showed negative correlation
with birthweight. The increases in both zymogen and in activity state appear to contribute
to the factor VIIc rise. The extent of this rise appears to be influenced by maternal
weight gain. Increased factor VII activation is associated with reduced foetal growth.