Preeclampsia (PE) is a serious pregnancy complication characterized by new-onset hypertension and signs of maternal organ dysfunction, often accompanied by placental abnormalities and systemic endothelial dysfunction. PE is associated with adverse maternal and perinatal outcomes and confers an increased long-term risk of cardiovascular and metabolic disease for both mother and offspring.

This prospective observational cohort study aims to establish a longitudinal pregnancy and birth cohort of women diagnosed with preeclampsia. Pregnant women with a clinical diagnosis of PE according to current obstetric guidelines will be recruited at their initial presentation either in the in- or outpatient clinic or in the delivery ward, respectively and followed through late pregnancy, delivery, and early postpartum.

Participants will undergo study visits during pregnancy, sample collection at delivery, and a postpartum visit 8-12 weeks after birth. Clinical data, physical measurements, questionnaire-based information, and biological samples will be collected from mothers and infants to enable comprehensive phenotyping of pregnancies complicated by preeclampsia.

Data and biosamples from this cohort will be used for descriptive and hypothesis-driven analyses and may be compared with data from an existing longitudinal cohort of healthy pregnancies to support interpretation of preeclampsia-associated biological and clinical changes.

Preeclampsia (PE) is a pregnancy-specific hypertensive disorder characterized by new-onset hypertension and signs of maternal organ dysfunction, often accompanied by placental abnormalities and systemic endothelial dysfunction. PE is associated with increased perinatal morbidity and an elevated long-term risk for cardiovascular and metabolic disease in both mothers and offspring. Despite its clinical relevance, the biological mechanisms underlying PE and its long-term consequences are not fully understood.

This prospective, monocentric observational cohort study is designed to establish a well-characterized longitudinal pregnancy and birth cohort of women diagnosed with PE. The primary objective is to collect clinical data and biological samples across pregnancy, delivery, and early postpartum to support detailed phenotyping of PE pregnancies and early-life outcomes.

Approximately 50 pregnant women with a confirmed diagnosis of PE will be recruited per year at the Department of Obstetrics and Gynecology. Eligible participants are women aged 18 years or older with an ongoing pregnancy and a clinical diagnosis of PE according to current obstetric guidelines. Women with major fetal anomalies are excluded.

Study participation includes four time points:

1. optional: a visit following PE diagnosis,
2. optional: a late pregnancy visit,
3. sample and clinical data collection at delivery, and
4. a postpartum follow-up visit 8-12 weeks after birth.

At each study visit, standardized clinical assessments, physical measurements, and questionnaire-based information will be collected. Maternal assessments include hemodynamic assessments, anthropometry, body composition. Fetal growth is assessed by routine obstetric ultrasound. At delivery, perinatal samples such as placenta, umbilical cord, and cord blood are collected. Postnatal assessments include maternal and infant anthropometry and selected cardiovascular measurements where applicable.

Biological samples collected longitudinally may include blood, urine, saliva, vaginal swabs, breast milk, placental tissue, umbilical cord tissue, and umbilical cord blood. Samples are processed and stored in a biobank for future analyses following separate ethical approvals. Clinical metadata include pregnancy outcomes, PE severity, treatment and management, delivery characteristics, and neonatal outcomes.

Lifestyle and behavioral factors, including nutrition and physical activity, are assessed using standardized questionnaires. Data are pseudonymized and handled in accordance with applicable data protection regulations.

This study is designed as a cohort and sample collection platform.

For contextual comparison, data and biosamples from an existing longitudinal cohort of healthy pregnancies will be used where appropriate. Alignment of visit timing and data collection procedures allows comparative analyses between PE and normotensive pregnancies.

Inclusion Criteria:

• Ongoing pregnancy with preeclampsia regardless the gestational age diagnosed for PE

Exclusion Criteria:

• Maternal or fetal genetic abnormalities

Pregnant women diagnosed with preeclampsia who present at our clinic, either in the in- or outpatient clinic or in the delivery ward, respectively.