Venous thromboembolism in pregnancy among Chinese women in a regional hospital in Hong Kong: a 20-year cross-sectional case-control study

Objective: To determine the prevalence and risk factors of venous thromboembolism (VTE) in pregnancy among Chinese women in a regional hospital. Methods: Medical records of ethnic Chinese residents who delivered at ≥24 weeks of gestation or earlier with active resuscitation between January 2004 and December 2023 at Pamela Youde Nethersole Eastern Hospital were retrospectively reviewed. To determine VTE prevalence, cases occurring during pregnancy and the postpartum period (up to 6 weeks after delivery) were identified. To determine risk factors for VTE, cases were compared with matched controls (within 3 days of the delivery date) at a 1:5 ratio. Results: In total, 22 cases of VTE occurring in the antepartum (n=15) or postpartum (n=7) period were identified. The prevalence was 0.5 per 1000 deliveries. Of the 22 cases, 16 were deep vein thrombosis, three were pulmonary embolism, and three involved both conditions. The most common symptom was limb swelling or pain (n=17). Two patients experienced cardiac arrest and underwent perimortem Caesarean section and subsequent mechanical thrombectomy by interventional radiologists. The remaining 20 patients with VTE received low-molecular-weight heparin treatment. The case and control groups were comparable, except that the case group had higher rates of substance use (13.6% vs 0.9%, p=0.001), varicose veins (4.5% vs 0%, p=0.025), preterm delivery (27.3% vs 7.3%, p=0.005), Caesarean section (63.6% vs 36.4%, p=0.018), blood transfusion (22.7% vs 2.7%, p<0.001), and stillbirth or neonatal death (4.5% vs 0%, p=0.025). Conclusion: The prevalence of VTE in pregnancy among Chinese women in Hong Kong was 0.5 per 1000 deliveries, lower than that reported internationally. The risks and benefits of pharmaco-prophylaxis should be weighed on an individual basis.