Summary
ADAMTS13 dysfunction has been involved in the pathogenesis of Thrombotic Thrombocytopenic
Purpura. This disorder occurs more frequently in women and, in 13% of them, is associated
with pregnancy. However, there is little information on the protease behaviour in
normal pregnancy. We studied von Willebrand factor and ADAMTS13 activity changes in
normal non-pregnant, pregnant and post-delivery women. Fifty-five non-pregnant women,
normal blood bank donors, who were not taking contraceptive pills were included as
controls. A prospective cross-sectional study of 270 normal pregnant and post-delivery
women was carried out. ADAMTS13 activity decreased progressively as from the period
of 12–16 weeks up to the end of early puerperium (mean 52%, range 22–89, p < 0.0001),
to increase slightly thereafter. Nulliparous presented mildly lower levels of ADAMTS13
activity than parous women (65% vs. 83%, p=0.0003), and primigravidae than multigravidae
between 6–11 weeks up to 17–23 weeks of pregnancy (69% vs. 80%, p=0.005). Although
in all women the protease levels were the same by blood groups, the O blood group
non-pregnant women showed a higher mean of ADAMTS13 activity than those non-O (78%
vs. 69%, p= 0.064). Our results suggest that the changing levels of protease activity
during pregnancy and puerperium, induced by unidentified mechanisms, could render
the peripartum time more vulnerable to developed thrombotic microangiopathies.
Keywords
ADAMTS13 activity - normal women - pregnancy - puerperium