Participants will be randomly assigned to either the intervention arm (mHealth application users) or the control arm, in which participants will record their data on paper or in Excel according to standard practice or the recommendation of their study physician.

Participants in the intervention arm will use the mHealth application daily from gestational week 20 until delivery. The application will collect and analyze a range of health-related data, including self-reported symptoms, blood pressure measurements, and proteinuria test results. The application processes these data and evaluates the degree of deviation of measured values from predefined normal ranges. Each parameter is assessed on a scale of 1 to 3, with threshold values indicating increased risk established in collaboration with the study physician and in accordance with standards of care.

The study physician is informed of deviations from normal values through color-coded indicators displayed within the application (without automated notifications), based on which further clinical management may be determined.

Participants in the control arm will not use the mHealth application. Instead, they will monitor and record their health data according to instructions provided by their study physician and in accordance with standard care protocols and routine clinical practice. These instructions will be provided at the same time points as those used in the intervention arm, ensuring comparable follow-up throughout the study period. Participants in the control arm will be instructed to adhere consistently to the data collection and self-monitoring procedures until delivery.

Importantly, this is not a medical device study, and the mHealth application is not classified as a medical device. No aspect of standard care will be withheld from any participant. All participants will continue to receive routine prenatal care and attend scheduled prenatal visits in accordance with established clinical guidelines.

Inclusion Criteria:

• Age between 18 and 45 years. Each participant will be enrolled in the study no earlier than the 20th week of pregnancy.

Presence of at least one primary risk factor:

• Pre-gestational hypertension.
• Gestational hypertension.
• Positive screening for preeclampsia.

The presence of additional secondary risk factors (e.g., controlled type 1 or type 2 diabetes mellitus, obesity with BMI ≥ 30) may be recorded but is not sufficient on its own for inclusion in the study without meeting at least one primary criterion.

Exclusion Criteria:

• Uncontrolled diabetes and/or diabetes during the last 3 months prior to enrolment in this study.
• Presence of a gynaecological disease that increases the risk of pregnancy complications, except for those conditions specifically listed in the inclusion criteria (e.g., chronic hypertension, gestational hypertension, pre-gestational hypertension, diabetes mellitus, obesity, or morbid obesity).
• Participant with active malignant disease.
• Participant with alcohol or drug abuse during the recruitment and during the trial course.
• Participant enrolled in another clinical trial during the last 3 months prior to enrolling in this study.
• Participants who, in the opinion of the study physician, may interfere with optimal participation in the study or may pose a risk to the participant.
• Characteristics indicating a poor understanding of the study or characteristics that indicate the participant may have poor compliance with the study protocol.
• Participants with severe or uncontrolled depression, which in the opinion of the study physician could influence participant's participation in the study; participants with stable depression and/or on a stable dose of an anti-depressant for at least three months may be included.

Pregnant women