Abstract
Background Although the rate of maternal mortality has declined over the past few decades, pulmonary embolus (PE) remains an important cause of maternal deaths. Little is known about the associations of specific periods of gestational weight gain with detailed PE and deep venous thrombosis (DVT). We explored the incidence of pregnancy-related venous thromboembolism (VTE) in China and assessed the associations of maternal weight gain in different periods of pregnancy with VTE.Methods In a retrospective case-control study conducted in in Shanghai First Maternity and Infant Hospital from January 1st, 2017 to July 31th, 2021, 151 cases (11.7 per 10000) of venous thromboembolism (VTE) within pregnancy or the first 6 postnatal weeks were identified. 302 controls without VTE who gave birth at the same time as the cases were selected. Maternal pre-pregnancy weight, weight in early, mid and late pregnancy and other maternal pregnancy and newborn characteristics were obtained. GWG was standardized into gestational age-specific z-scores stratified by body mass index (BMI) and categorized as low (z score <-1), normal (-1 to 1), and high (>1). The adjusted odds ratios (aORs) and 95% confidence intervals (CIs) were estimated through log-binomial regression models. Interaction effects between gestational weight gain (GWG) and some other adjustment factors were tested, further stratified analyses were performed separately where interaction terms were significant. Results There were 65.6% (99 of 151) of pulmonary embolus (PE) alone and 34.4% (52 of 151) of deep venous thrombosis (DVT) alone or combined with PE. For all pre-pregnancy BMI categories (underweight, normal weight, overweight and obese), there was no statistical association between maternal weight gain of all gestational intervals and DVT or all VTE in this study. However, for PE, there was observed protective effects of low weight gain (aOR 0.79; 95% CI 0.37–1.68) and significantly increased risks of high weight gain (aOR=1.47; 95% CI: 1.03-2.09) among normal-weight women in early pregnancy. Similarly, a tendency towards decreased risk at lower weight gain throughout pregnancy (aOR 0.79; 95% CI 0.37–1.68) and significantly increased risk at higher values (aOR=1.52; 95% CI: 1.01-2.31) for PE was observed in normal-weight women. As for underweight and overweight women, results from the categorical model for early, late or total pregnancy weight gain indicated an increased risk in PE at both low and high weight gain, but confidence intervals were wide.Conclusion Chinese women have a higher risk of PE than the foreigner counterparts. Maternal weight gain in total or early pregnancy is an important risk factor for PE. In order to effectively improve maternal and child outcomes, intensive weight management that continues through pregnancy may be indispensable.
Factors associated with maternal weight gain rate throughout pregnancy in women with normal and excessive pre‐pregnancy weight (LB446)
