In 2017, the American College of Cardiology (ACC) and American Heart Association (AHA) guidelines built on evidence that elevated blood pressure increases cardiovascular mortality in the general population, Reclassification of BP; however, these diagnostic definitions do not include pregnant women, and whether newly diagnosed stage 1 hypertension affects pregnancy complications remains unclear. In this study, the combination of maternal factors, MAP and PLGF was used to comprehensively analyze the risk factors of preeclampsia through the "Bayesian rule" developed by the British Fetal Medicine Foundation (FMF). According to the guidelines and consensus, the pregnant women were considered to be at high risk when the calculated risk was higher than 1% of the population. To compare the pregnancy outcomes of women with normal blood pressure in the first trimester and stage 1 hypertension in different risk groups, and to find out whether screening for preeclampsia can be omitted for women with normal blood pressure in the first trimester, while screening for preeclampsia should still be performed for women with stage 1 hypertension as an independent moderate risk factor, and finally to optimize the screening strategy for preeclampsia.

Based on first-trimester BP measurements, pregnant women were reclassified as normotensive (systolic BP < 120mmHg and diastolic BP <80mmHg on at least two occasions) and stage 1 hypertensive (systolic BP 130-139 mmHg and/or diastolic BP 80-89 mmHg on at least two occasions, without a diagnosis of chronic hypertension and/or elevated BP). At the same time, based on the 2019 FIGO pre-eclampsia screening guidelines, it is recommended that all pregnant women should be screened for pre-eclampsia in the first trimester. In this study, pregnant women who combined maternal factors, MAP and PLGF were analyzed by the "Bayesian rule" developed by the British Fetal Medicine Foundation (FMF). Its online computing website: https://fetalmedicine.org/research/assess/preeclampsia/first-trimester. The individual risk of preterm PE was calculated at 11-14+1 weeks of gestation using the British Fetal Medicine Foundation (FMF) algorithm. Previous risk was calculated based on maternal demographic characteristics and obstetric history. Therefore, 1/100 was selected as the cut-off value, ≥1/100 was registered as high risk of preeclampsia, < 1/100 was registered as low risk of preeclampsia. For people with high risk of preeclampsia (≥1/100) evaluated in the first trimester, low-dose aspirin prevention for preeclampsia is recommended between 12 and 28 weeks of gestation (preferably before 16 weeks). And continued until 36 weeks. To compare the pregnancy outcomes of women with normal blood pressure in the first trimester and stage 1 hypertension in different risk groups, and to find out whether screening for preeclampsia can be omitted for women with normal blood pressure in the first trimester, while screening for preeclampsia should still be performed for women with stage 1 hypertension as an independent moderate risk factor, and finally to optimize the screening strategy for preeclampsia.

Inclusion Criteria:

1. Age ≥18 years old;
2. single live fetus with normal NT at 11-14+1 weeks of gestation;
3. Blood pressure < 140/90 mmHg before 14+1 week of gestation;
4. Plan to have prenatal examination and delivery in our hospital;
5. Sign informed consent.

Exclusion Criteria:

Underlying diseases (chronic hypertension, type 1 or type 2 diabetes, kidney disease, autoimmune disease).

All the subjects were pregnant women who delivered in our hospital.