The fibrinolytic system is involved in blood clot lysis and in other biolog
ical processes that require extracellular proteolysis such as ovulation, bl
astocyst implantation and throphoblastic invasion. An impaired fibrinolytic
capacity is a common feature in women suffering from unexplained early rec
urrent pregnancy loss. We carried out a prospective study with 114 patients
. Three groups were established: Group 1: women who had two or more unexpla
ined miscarriages of < 12 weeks of gestation (n = 52). Group 2: women who h
ad 2 or more embryo-implantation failure after embryo-transfer with good qu
ality embryos in assisted reproduction (n = 46). Group 3: women who had 2 o
r more embryo-implantation failure after embryo-transfer and one early loss
of a pregnancy achieved in a cycle of assisted reproduction ( n = 16). Fib
rinolytic pattern pre and post-occlusion test was carried out: ECLT, PAI-1i
, PAI-lb, t-PAi, t-PAb. In addition other studies were performed: LAG, ACA
IgG and IgM, fibrinogen, factor XII, APCR. A high prevalence of thrombophil
ic defects and hypofibrinolysis was observed in the three groups. The fibri
nolytic pattern was similar in the three groups, although a prolonged pre o
cclusion ECLT was more frequent in women with primary infertility (Group 2)
. Isolated hypofibrinolysis was found in 50% of the patients. The remaining
patients with hypofibrinolysis presented combined defects with LAG, ACA an
d abnormal APCR. The fibrinolytic pattern in women with or without antiphos
pholipid antibodies was similar, although an elevated pre occlusion PAI-1i
was more common in women without antiphospholipid antibodies. High prevalen
ce of fibrinolytic abnormalities observed in women with unexplained early r
ecurrent pregnancy loss and in women with repeated failure implantation aft
er embryo-transfer in assisted reproduction, suggests that hypofibrinolysis
could be a parameter of early reproductive failure.