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PREGNANCY AFTER COMBINED ORAL CONTRACEPTIVE-ASSOCIATED VENOUS THROMBOEMBOLISM: AN INTERNATIONAL RETROSPECTIVE STUDY OF OUTCOMES.

BACKGROUND
Few data are available on thrombotic outcomes during pregnancy and puerperium occurring after an initial provoked venous thromboembolic event (VTE).


OBJECTIVES
To describe thrombotic outcomes during pregnancy after a first combined oral contraceptive (COC)-associated VTE and the factors associated with recurrence Methods. This was an international multicentric retrospective study on patients referred for thrombophilia screening from January 1st 2010 to January 1st 2021 following a first COC-associated VTE, including women with neither inherited thrombophilia nor antiphospholipid antibodies and focusing on those who had a subsequent pregnancy under the same thromboprophylaxis treatment. Thrombotic recurrences during pregnancy and puerperium as well as risk factors for recurrence were analysed.


RESULTS
We included 2,145 pregnant women. A total of 88 thrombotic events, 58 antenatal and 29 postnatal, occurred, mostly during the first trimester of pregnancy and the first two weeks of puerperium. Incidence rates were 49.6 (37-62) per 1,000 patient-years during pregnancy and 118.7 (78-159) per 1,000 patient-years during puerperium. Focusing on pulmonary embolism, incidence rates were 1.68 (1-4) per 1,000 patient-years during pregnancy and 65.5 (35-97) per 1,000 patient-years during puerperium. Risk factors for antenatal recurrences were maternal hypercholestorolaemia and birth of a very small-for-gestational-age neonate. A risk factor for postnatal recurrence was the incidence of preeclampsia. Conclusions Our multicentric retrospective data show significant rates of VTE recurrence during pregnancy and puerperium in women with a previous VTE event associated with COC, despite a unique LMWH-based thromboprophylaxis. These results may provide benchmarks and valuable information for designing future randomized controlled trials.