10-09-2025

Imagen1sdfsd A blood test could replace Doppler ultrasound in pregnancies with small fetuses | UFV Study at the Universidad Privada Madrid

Introduction

An international study led by Vall d’Hebron Hospital, in collaboration with Francisco de Vitoria University, shows that analyzing placental biomarkers in blood can accurately identify pregnancies with small fetuses at risk of complications, thereby avoiding unnecessary induced labor and improving outcomes for mothers and newborns.

A clinical trial conducted at 20 Spanish hospitals has shown that measuring two proteins in maternal blood allows for the management of full-term pregnancies with low-birth-weight fetuses with the same level of accuracy as a Doppler ultrasound,. The study, known as GRAFD, has been published in the journal Nature Medicine and proposes a shift in the approach to medical decision-making during the final stages of pregnancy.

The test is based on the ratio of two placental biomarkers, sFlt-1 and PlGF, which, when measured, help determine whether it is advisable to induce labor or allow the pregnancy to continue until 39 or 40 weeks. This strategy has been shown to reduce the number of unnecessary inductions, decrease maternal and neonatal complications, and improve birth outcomes.

The research team includes Dr. Mar Gil and Dr. Raquel Martín, both researchers at Francisco de Vitoria University (UFV, specialists in maternal-fetal medicine at Torrejón University Hospital, and members of the iMaterna Foundation.

Imagen1sdfsd-1024x640 A blood test could replace Doppler ultrasound in pregnancies with small fetuses | UFV Study at the Universidad Privada Madrid

Image1sdfsd 1024x640 A blood test could replace Doppler ultrasound in pregnancies with small fetuses Study at a private university in Madrid

More accurate diagnosis, fewer premature births

In one out of every ten pregnancies, starting at 36 weeks, the estimated fetal weight is below the 10th percentile. However, not all of these cases pose a risk. Some babies are simply small but healthy (PEG o SGA), while others have actual fetal growth restriction (FGR o CIR), which increases the likelihood of complications during and after delivery.

The challenge lies in correctly distinguishing between the two. The standard tool, Doppler ultrasound, while useful, requires advanced technology and expertise, and tends to overdiagnose high-risk pregnancies, leading to premature induced labor.

“Doppler ultrasound has been key to fetal monitoring in recent decades, especially in high-risk pregnancies, but it has its limitations: many women end up being induced unnecessarily,” explains Mar Gil, who, in addition to being a researcher at UFV, works as a specialist at the Torrejón University Hospital. “With this blood test, we can be more precise and more cautious,” she insists.

Imagen2dfasfsdef-962x1024 A blood test could replace Doppler ultrasound in pregnancies with small fetuses | UFV Study at the Universidad Privada Madrid

Analysis of the sFlt-1 and PlGF biomarkers has proven to be just as effective as Doppler ultrasound in pregnancies with small fetuses, allowing more women to carry their pregnancies to term without the need for early intervention. (Source: infographic)

An objective test to determine whether there is a real risk

The test focuses on measuring two placental proteins, sFlt-1 and PlGF, which circulate in the mother's blood. If the ratio between them is 38 or higher, it indicates an increased risk of complications; if it is lower, the pregnancy can continue without the need for immediate intervention.

The study, which involved 1,088 pregnant women, compared two monitoring methods: one based on Doppler ultrasounds and the other guided solely by this blood test. Both were equally effective in preventing serious complications such as neonatal acidosis or the need for a cesarean section due to fetal heart rate abnormalities.

“Biomarker analysis provides a more physiological view of the condition of the placenta and the fetus,” notes Dr. Manel Mendoza, an obstetrician at Vall d’Hebron Hospital and the trial coordinator. “At this stage of pregnancy, biomarkers allow us to make safer, more informed, and less invasive decisions,” he says.

Better outcomes without inducing labor

Beyond the primary efficacy, the use of analytics revealed additional benefits. Women in the biomarker-guided group had fewer cases of preeclampsia and postpartum hemorrhage. The newborns had higher birth weights and fewer admissions to intensive care units due to respiratory distress.

In addition, the rate of induced deliveries before 39 weeks was significantly lower. “That means many women were able to carry their pregnancies to term without the need for early intervention, and that improves neonatal well-being and the childbirth experience,” adds Marta Lázaro-Rodríguez, an obstetrician at Germans Trias i Pujol University Hospital and a doctoral candidate in this line of research. “The goal is to intervene only when there is a real reason to do so,” she emphasizes.

Available at any facility with a basic laboratory

Given the need for advanced technology and trained professionals that comes with using Doppler ultrasound, this blood test can be performed at any facility with a basic clinical laboratory. This makes it a particularly valuable option in regional hospitals, rural areas, or countries with fewer resources.

Standardizing criteria also ensures consistency across facilities. “This type of test offers a viable solution for many facilities that lack advanced technology, enabling more consistent and reliable clinical decisions,” explains Anna Moreno, an obstetrician-gynecologist at Parc Taulí University Hospital in Sabadell.

“The fact that it’s a laboratory test means decisions are less dependent on subjective interpretation or technical availability,” adds Gil. “It’s a practical and realistic solution for many settings where it’s currently not possible to follow the standard protocol,” adds Mendoza.

A step toward more personalized and effective decisions

The GRAFD study proposes an approach that is better tailored to individual risk for managing pregnancies with small fetuses. Its findings support the gradual incorporation of this type of test into clinical protocols as a valid alternative to Doppler in certain contexts.

“This approach represents a way of practicing medicine that is better tailored to the needs of each pregnancy. It’s not about cutting back on resources, but about knowing when to use them and when not to. That is the foundation of safer, more personalized care,” conclude Mar Gil and Manel Mendoza.

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