Effects of Monitoring Blood Pressure During Pregnancy

Inclusion Criteria: * Women with a single pregnancy before 12 weeks of pregnancy * The presence of any of the following risk factors: age \> 30 years, a history of eclampsia, a family history of eclampsia, obesity (BMI ≥ 30 Kg/m2), and a history of gestational hyperglycemia (pregestational type 1 and type 2 diabetes; gestational manifest diabetes and gestational diabetes requiring insulin treatment), preexisting chronic hypertension, kidney disease, and autoimmune diseases such as systemic lupus erythematosus and antiphospholipid syndrome. * Signed the informed consent can be continuously followed up. * Permanent population living in the study area. * All subjects received routine antenatal examination and treatment. Exclusion Criteria: * Termination of pregnancy before 20 weeks * Withdraw from the study * Lost visitors