Risk factors for recurrence during a pregnancy following a first venous thromboembolism: A French observational study

Pregnancy-related venous thromboembolism in Wuhan, China 2010-2022: A case-control study

OBJECTIVE

To explore the time trends and risk factors for pregnancy-related venous thromboembolism (VTE) in the Chinese population.

METHODS

A case-control study was conducted with 120 652 pregnancies between Jan 2010 and June 2022 in Wuhan, China. Medical records from pregnant patients with VTE and patients without VTE were reviewed and analyzed.

RESULTS

There were 197 cases of VTE diagnosed during pregnancy or postpartum, with an overall incidence of 1.63 per 1000 pregnancies, and the incidence rate trend of VTE was increasing year by year and then declining. The incidence of deep venous thrombosis (DVT) was 1.24 per 1000 pregnancies (76.1%). Consistent with previous studies, most VTE occurred in the puerperium (1.05 per 1000 pregnancies, 64.5%). Significant risk factors included immobility, previous VTE, systemic infection, BMI over 30, and hypertensive disorders of pregnancy.

CONCLUSION

Pregnancy-related VTE is not uncommon in China which is consistent with current foreign reports, and the change in incidence trend may be related to greater physicians' understanding of VTE and effective preventive measures after the publication of Chinese guidelines.

A retrospective study on the use of low-molecular-weight heparin for prevention of pregnancy-related recurrent venous thromboembolism and obstetrical complications

BACKGROUND

The risk of venous thromboembolism (VTE) is increased during pregnancy and it is further increased together with pregnancy complications in women with personal history of VTE and thrombophilia abnormalities. It is unclear how the use of low-molecular-weight heparin (LMWH) may prevent such complications.

OBJECTIVE

To evaluate the potential benefits and risks of the use of LMWH for prevention of pregnancy-related VTE and obstetrical complications in the first pregnancy after a previous VTE.

METHODS

This retrospective cohort study includes fertile women referred to the Thrombosis Center from January 2000 to September 2018 for a thrombophilia work-up, after having had at least one previous VTE and one pregnancy thereafter. Data on pregnancy-related recurrent VTE, pregnancy outcomes and the use of LMWH were collected.

RESULTS

Among 208 women, no thrombosis or major bleeding was recorded in 138 pregnancies conducted with LMWH, whereas 10 VTE (14%) were recorded in 70 pregnancies conducted without. Nine women (90%) with recurrent VTE had had a previous hormone-related event. The incidence of miscarriage was lower in pregnancies with LMWH than in those without (11% vs. 26%, relative risk 0.4, 95% confidence interval: 0.2-0.8), whereas late obstetrical complications and terminations were similar in the two groups. The prevalence of terminations was doubled in women with thrombophilia (12%) than in those without (6%).

CONCLUSIONS

LMWH prophylaxis during pregnancy appears to be effective and safe for the prevention of recurrent VTE and may reduce the incidence of miscarriage.

Intermediate-dose versus low-dose low-molecular-weight heparin in pregnant and post-partum women with a history of venous thromboembolism (Highlow study): an open-label, multicentre, randomised, controlled trial

BACKGROUND

Pregnancy-related venous thromboembolism is a leading cause of maternal morbidity and mortality, and thromboprophylaxis is indicated in pregnant and post-partum women with a history of venous thromboembolism. The optimal dose of low-molecular-weight heparin to prevent recurrent venous thromboembolism in pregnancy and the post-partum period is uncertain.

METHODS

In this open-label, randomised, controlled trial (Highlow), pregnant women with a history of venous thromboembolism were recruited from 70 hospitals in nine countries (the Netherlands, France, Ireland, Belgium, Norway, Denmark, Canada, the USA, and Russia). Women were eligible if they were aged 18 years or older with a history of objectively confirmed venous thromboembolism, and with a gestational age of 14 weeks or less. Eligible women were randomly assigned (1:1), before 14 weeks of gestational age, using a web-based system and permuted block randomisation (block size of six), stratified by centre, to either weight-adjusted intermediate-dose or fixed low-dose low-molecular-weight heparin subcutaneously once daily until 6 weeks post partum. The primary efficacy outcome was objectively confirmed venous thromboembolism (ie, deep-vein thrombosis, pulmonary embolism, or unusual site venous thrombosis), as determined by an independent central adjudication committee, in the intention-to-treat (ITT) population (ie, all women randomly assigned to treatment). The primary safety outcome was major bleeding which included antepartum, early post-partum (within 24 h after delivery), and late post-partum major bleeding (24 h or longer after delivery until 6 weeks post partum), assessed in all women who received at least one dose of assigned treatment and had a known end of treatment date. This study is registered with ClinicalTrials.gov, NCT01828697, and is now complete.

FINDINGS

Between April 24, 2013, and Oct 31, 2020, 1339 pregnant women were screened for eligibility, of whom 1110 were randomly assigned to weight-adjusted intermediate-dose (n=555) or fixed low-dose (n=555) low-molecular-weight heparin (ITT population). Venous thromboembolism occurred in 11 (2%) of 555 women in the weight-adjusted intermediate-dose group and in 16 (3%) of 555 in the fixed low-dose group (relative risk [RR] 0·69 [95% CI 0·32-1·47]; p=0·33). Venous thromboembolism occurred antepartum in five (1%) women in the intermediate-dose group and in five (1%) women in the low-dose group, and post partum in six (1%) women and 11 (2%) women. On-treatment major bleeding in the safety population (N=1045) occurred in 23 (4%) of 520 women in the intermediate-dose group and in 20 (4%) of 525 in the low-dose group (RR 1·16 [95% CI 0·65-2·09]).

INTERPRETATION

In women with a history of venous thromboembolism, weight-adjusted intermediate-dose low-molecular-weight heparin during the combined antepartum and post-partum periods was not associated with a lower risk of recurrence than fixed low-dose low-molecular-weight heparin. These results indicate that low-dose low-molecular-weight heparin for thromboprophylaxis during pregnancy is the appropriate dose for the prevention of pregnancy-related recurrent venous thromboembolism.

FUNDING

French Ministry of Health, Health Research Board Ireland, GSK/Aspen, and Pfizer.

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.