Introduction
Deep vein thrombosis (DVT) and pulmonary embolism (PE) are collectively referred to as venous thromboembolic disease (VTE). Although the rate of maternal mortality has declined over the past few decades, PE remains an important cause of maternal deaths[1,2]. During pregnancy, a women’s risk of VTE is increased by 6 times, with reported incidence ranging from 0.5 to 2.0 per 1000 deliveries[3,4]. Approximately 75–80% of cases of pregnancy-associated VTE are caused by DVT, and 20–25% of cases are caused by PE[5]. However, few studies have examined trends in the incidence of pregnancy-related VTE in China.
Several studies have already identified risk factors for pregnancy-related VTE, including advanced maternal age, greater body mass index (BMI), cesarean delivery, preeclampsia, postpartum hemorrhage and newborns with low birth weight[1,6-11]. They help care providers to target the use of thromboprophylaxis to women at risk to maximize its benefit[12]. However, few studies have evaluated gestational weight gain (GWG) as a risk factor for VTE[13]. Although insufficient and excessive maternal weight gain has been linked with increased risks of VTE[13], they have often not accounted for the effects of weight gain during certain periods of pregnancy. Furthermore, the associations of specific periods of GWG with detailed PE and DVT has not been reported. In addition, few studies have examined trends in the incidence of pregnancy-related VTE in China, and these studies have shown variable results[14,15].
For this retrospective case–control study of women, our objective was to explore the incidence of pregnancy-related VTE in China, and evaluate the association of maternal weight gain in different periods of pregnancy with detailed pulmonary embolism (PE) and deep vein thrombosis (DVT).