Introduction
Preeclampsia is a classic disorder characterized by the onset of hypertension which begins after 20 weeks of pregnancy together with a new onset of significant proteinuria,(1) which is one of the main causes of perinatal morbidity as well as mortality of both the mother and the child. (2-4) Preeclampsia affects around 2.3% to 4% of Chinese pregnant women,(5, 6) and is also related to survivors having substantial risks of developing cardiovascular disease (CVD) and cerebrovascular disease in the long-term. (7, 8) In addition, several lines of evidence have demonstrated that early intervention, such as administering aspirin in small doses, would help significantly lower the risks of mothers developing preeclampsia.(9-11) Therefore, early identification of pregnant women at risk of developing preeclampsia during the first trimester of pregnancy is of the utmost importance to minimize adverse perinatal events,(12) and to initiate appropriate timely therapeutic interventions.(12, 13)
Chronic hypertension and elevated blood pressure before 20 weeks of gestation are associated with an increased risk of pregnant women developing preeclampsia.(14) In 2017, the criteria for the diagnosis of hypertension in non-pregnant adults, recommended by the American College of Cardiology / American Heart Association (ACC/AHA), were reduced to a threshold of 130/80 mmHg, while the previous cutoff value was 140/90 mmHg.(15) Data from a recent large cohort study showed that the lower diagnostic threshold for hypertension in the 2017 ACC/AHA guidelines markedly predicted those women who would go on to develop preeclampsia.(16) Our previous study also found that women with a normal body mass index (BMI) who met diagnostic criteria of the stage 1 hypertension of ACC/AHA Blood Pressure revised guideline were 3 times more likely to develop preeclampsia.(14) However, there is not enough evidence to support the efficacy of lower blood pressure thresholds for identifying women at heightened risk for preeclampsia. (17-21)
The risks of preeclampsia were considered to be screened based on maternal risk factors.(22) Major maternal metabolic risk factors such as being overweight/obese increase the risks of gestational hypertensive disorders.(23) High serum triglyceride (TG) concentrations during the first trimester have been confirmed to increase the risks of preeclampsia independent of BMI.(24) However, previous studies lacked the power to assess robustly whether differences in the preeclampsia risk at different blood pressure thresholds were correlated with different maternal pre-pregnancy BMI and early-pregnancy TG concentrations. Information regarding maternal obesity and high TG concentrations across a range of maternal blood pressure thresholds will be important for the identification of mothers at an increased risk of developing preeclampsia. The current study pooled a big cohort from China to assess the impact of maternal pre-pregnancy BMI and early-pregnancy TG concentrations on the association with increased blood pressure thresholds by applying the 2017 ACC/AHA blood pressure guideline criteria of the risk for preeclampsia.