Routine Blood Tests Years Before Pregnancy Could Identify Preeclampsia Risk

High blood pressure during pregnancy is common and can progress to pre-eclampsia, making close monitoring at antenatal visits essential. However, most risk assessment begins only after pregnancy has started. Identifying risk earlier could improve how care teams counsel patients and plan preventive strategies. New findings show that routine blood tests performed several years before pregnancy are associated with later risk of hypertension and pre-eclampsia.

Researchers at Karolinska Institutet (Stockholm, Sweden) analyzed pregestational cardiometabolic biomarkers measured during health examinations four to six years before a first pregnancy. The approach evaluates routinely collected indicators—blood sugar, blood lipids, haptoglobin as a marker of low‑grade inflammation, and the TyG index, described as reflecting impaired glucose metabolism—to stratify risk. Associations were assessed using the Stockholm-based AMORIS database and subsequent linkage to national registers.

The cohort comprised just over 35,000 women in Stockholm, Sweden, all expecting their first child. Baseline laboratory values came from health examinations conducted four to six years before conception, and pregnancy outcomes were ascertained from national registers. The investigation is described as an observational study and was published online on April 30, 2026, in JAMA Network Open.

Overall, 5.5% of participants developed high blood pressure or pre‑eclampsia during pregnancy. Depending on which biomarker was elevated, 5.5% to 12.8% of women with pregestational metabolic disturbances were affected, compared with 4.1% to 5.3% among women whose levels were within the normal range. Even moderately elevated levels of LDL cholesterol, triglycerides, apolipoprotein B, haptoglobin, and the TyG index were associated with increased risk.

The researchers note that the causes of pregnancy‑related hypertension are complex and not fully understood. Because the study is observational, the results should be interpreted with caution and do not establish causality. Next steps include evaluating whether early abnormalities in blood sugar, lipids, and inflammation predict other outcomes such as gestational diabetes and preterm birth, and examining links with women’s long‑term cardiovascular health.=

“Our results suggest that the increased risk may begin even at levels currently considered normal. This means that routine blood tests could be used as an additional tool to help healthcare professionals assess risk and discuss lifestyle with women of childbearing age, both before and early in pregnancy,” said Karin Leander, senior lecturer and associate professor at the Institute of Environmental Medicine, Karolinska Institutet.

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