Routine blood test can predict pre-eclampsia among women in labour, suggests study

A simple blood test could help doctors identify women in labor who are at risk for preeclampsia-a leading cause of maternal death-and take precautions to prevent it, according to research presented at the ANESTHESIOLOGY® 2024 annual meeting.

Between 5% and 10% of pregnant women develop preeclampsia (sudden high blood pressure and protein in the urine), according to the Centers for Disease Control and Prevention (CDC). Black women are 60% more likely to develop preeclampsia than white women, and more likely to die or have serious outcomes such as kidney damage, the CDC notes. While preeclampsia can develop as early as the 20th week of pregnancy, the study focused on identifying women who were at risk for preeclampsia when they were admitted to the hospital in labor.

Researchers have determined doctors can predict a woman’s risk of developing preeclampsia by calculating the ratio of two blood proteins-fibrinogen and albumin-measured in routine blood tests done when women in labor enter the hospital. Fibrinogen is involved in blood clotting and inflammation, while albumin helps maintain fluid balance and carries hormones, vitamins and enzymes throughout the body. Both can be disrupted with preeclampsia-fibrinogen may be elevated, albumin may be reduced, or both can occur.

There is no universally established normal value for this fibrinogen-to-albumin ratio (FAR), which can range from 0.05 to 1 or higher. Higher FAR values are often associated with increased inflammation, infection or serious health conditions, and the higher the FAR, the greater the concern. This trend has been consistently seen when FAR is used to evaluate other inflammatory conditions, such as rheumatoid arthritis, cardiovascular diseases and inflammatory bowel disease.

In the study, researchers analyzed the records of 2,629 women who gave birth between 2018 and 2024, 1,819 who did not have preeclampsia, 584 who had preeclampsia with mild features or symptoms (including blood pressure of 140/90 mm Hg or higher, but no significant signs of organ damage), and 226 who had preeclampsia with severe features or symptoms (including blood pressure of 160/110 mm Hg or higher and signs of organ damage, including severe headaches, high liver enzymes, visual disturbances, low platelet count or kidney impairment). The researchers determined those who had a higher FAR were more likely to develop preeclampsia than those with a lower FAR. They found that the predicted likelihood of developing any degree of preeclampsia was 24% for patients with a FAR of at least 0.1 on admission to the hospital, and it rose to more than 41% when that value was above 0.3.

If a woman in labor is found to be at increased risk for preeclampsia based on the FAR and other clinical indicators-such as being older than 35 or having chronic high blood pressure or obesity-obstetricians and anesthesiologists can take extra precautions to reduce the risk and ensure the patient’s blood pressure and fluid levels remain stable and controlled. For example, they can order more frequent blood pressure checks or lab tests. If the FAR indicates a woman is at risk for preeclampsia with severe symptoms, an epidural for pain management can be placed early before it becomes too risky.

“While FAR has been associated with other inflammatory conditions, its specific application to preeclampsia and preeclampsia with severe symptoms has not been reported in a group this large and racially diverse,” said Lucy Shang, B.A., lead author of the study and a medical student at the Icahn School of Medicine at Mount Sinai, New York. “Our study shows that FAR can be a predictive tool that gives anesthesiologists and obstetricians a new method for assessing a laboring mom’s risk of developing preeclampsia when they are admitted to the hospital.”

She noted that while this ratio should be assessed for all pregnant women, calculating the FAR is especially important for women who are at higher risk for preeclampsia, such as Black women and those with high blood pressure and obesity. “Additional research is needed to determine the exact range of the FAR that would be considered concerning and would be helpful to incorporate into routine prenatal care as a predictive tool for early identification of preeclampsia,” she said.

Reference:

Routine blood test can identify laboring women at risk for preeclampsia, prompt interventions to protect mom and baby, American Society of Anesthesiologists, Meeting: Anesthesiology 2024.