summary
Untreated hereditary antithrombin deficiency in pregnancy is associated with maternal
venous thromboembolism (VTE) and possibly with fetal loss. Thromboprophylaxis during
pregnancy is recommended, but dosages remain controversial. Our objective was to perform
a retrospective assessment of thrombotic events and pregnancy outcomes in women with
hereditary antithrombin deficiency managed according to a standard protocol. Pregnancies
in individuals with hereditary antithrombin deficiency were identified from a hospital
database. Women with no prior VTE received enoxaparin 40 mg daily until 16 weeks gestation
and thereafter 40 mg twice daily. Women with prior VTE received intermediate dose
enoxaparin (1 mg/kg) once daily, increased to twice daily at 16 weeks and anti-Xa
monitored dosing. Thromboprophylaxis was stopped at initiation of labour or 12 hours
prior to caesarean and 50 IU/kg antithrombin concentrate given. Thromboprophylaxis
was restarted after delivery. Eighteen pregnancies in 11 women with antithrombin deficiency
were identified. Seventeen pregnancies (94%) were successful. Median gestation was
39 weeks (range 30–41) and median birth-weight was 2,995 g (910–4,120 g),but 6/17
infants (35%) were small for gestational age (p=0.01). Estimated blood loss at delivery
was median 375 ml (200–600 ml). Four pregnancies were complicated by VTE; one newly
presented with a thrombotic event, two patients were not taking thromboprophylaxis
and one occurred despite thromboprophylaxis. Two novel mutations(p.Leu317Ser and p.His33GInfsX32)
are described. In conclusion, in antithrombin deficiency the use of low-molecular-weight
heparin in pregnancy and puerperium with antithrombin concentrate predelivery was
associated with successful pregnancy outcome; rates of VTE appear to be lower than
previously reported, but remain elevated
Keywords
Hereditary antithrombin deficiency - pregnancy