Healthy Umbilical Cord

Fetal Health Check: Are Your Umbilical Artery Measurements Accurate?

Lena Kashyap in Health & Wellness December 2025 • 4 min read.

"New research from Chile highlights potential inaccuracies in standard fetal monitoring, urging a review of current guidelines for assessing placental health and fetal well-being."

For expectant parents, few things are as crucial as ensuring their baby is developing healthily throughout pregnancy. Regular monitoring, including Doppler ultrasound assessments of the umbilical artery, plays a vital role in gauging fetal well-being. These assessments help doctors evaluate blood flow, which is essential for delivering oxygen and nutrients to the growing fetus.

Doppler velocimetry of the umbilical artery has become a cornerstone in managing high-risk pregnancies, especially those involving intrauterine growth restriction (IUGR). By measuring the resistance or impedance in the placenta (the organ providing oxygen and nutrients) through the umbilical artery, healthcare providers can gain insights into the fetus's condition.

However, a recent study conducted in Chile is challenging some of the long-standing norms in this area. The researchers found that the standard reference ranges for umbilical artery measurements might not be accurate for their population, potentially leading to underdiagnosis of placental insufficiency. This raises important questions about the universality of current guidelines and the need for tailored approaches in fetal monitoring.

Why Standard Umbilical Artery Measurements May Not Be Accurate for Everyone

The original reference ranges for umbilical artery measurements, like the Pulsatility Index (PI), were established over two decades ago. While these standards have been widely adopted, including in Chilean perinatal guidelines, concerns have been growing about their applicability across diverse populations. The Chilean researchers noticed a discrepancy: fewer altered Doppler results than expected, even in severe cases of fetal growth restriction. This observation spurred them to investigate whether the existing reference ranges truly fit their patient population.

The Chilean study was designed to create a normal curve for the Pulsatility Index (PI) in the umbilical arteries of fetuses between 11 and 41 weeks of gestation. The study was a cross-sectional study including low-risk singleton pregnancies. Doppler velocimetry was performed on the umbilical artery to measure the PI.

Participants: 877 fetuses in low-risk, singleton pregnancies.
Methodology: Doppler ultrasound measurements of the umbilical artery performed between 11 and 41 weeks gestation.
Measurements: Pulsatility Index (PI) and time-averaged mean velocity.

The study revealed that the IP values in the Chilean population were different from the Arduini curves, which are widely used as a standard. Specifically, the IP values were between 18% and 22% lower than the Arduini curves. The t/2 curves were similar to what has been previously reported.

What Does This Mean for Expectant Parents?

The Chilean study underscores the importance of ongoing research and the need to adapt medical guidelines to specific populations. While the current standards for umbilical artery measurements have served as a valuable tool, healthcare providers should be aware of their limitations and consider the potential for inaccuracies when applying them to diverse populations. It suggests that implementing these new values could help reduce the rate of placental insufficiency underdiagnosis.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.4067/s0717-75262014000400002, Alternate LINK

Title: Curvas Normales De Índices De Pulsatilidad Y Tiempo Medio De Desaceleración De Arteria Umbilical Fetal En Población Chilena

Subject: Obstetrics and Gynecology

Journal: Revista chilena de obstetricia y ginecología

Publisher: Publicidad Permanyer, SLU

Authors: Juan Carlos Bustos V, Vivian González C

Published: 2014-01-01

Everything You Need To Know

What is the role of umbilical artery Doppler assessments during pregnancy?

Umbilical artery Doppler assessments are crucial for monitoring fetal well-being. These assessments, utilizing Doppler velocimetry, evaluate blood flow in the umbilical artery, which indicates how efficiently the placenta is delivering oxygen and nutrients to the fetus. They are a cornerstone in managing high-risk pregnancies, particularly those involving intrauterine growth restriction (IUGR), by measuring placental resistance or impedance.

Why might standard umbilical artery measurements, like the Pulsatility Index (PI), be inaccurate for all populations?

Standard reference ranges for umbilical artery measurements, such as the Pulsatility Index (PI), were established over two decades ago. A recent Chilean study indicates that these ranges may not be universally applicable due to variations across different populations. The study found that the PI values in the Chilean population were significantly lower (18% to 22%) than the widely used Arduini curves, suggesting a need for tailored, population-specific guidelines to avoid underdiagnosis of placental insufficiency.

What did the Chilean study reveal about the Pulsatility Index (PI) in their population, and how does it compare to existing standards like the Arduini curves?

The Chilean study, involving 877 low-risk, singleton pregnancies, found that the Pulsatility Index (PI) values in their population were notably different from the Arduini curves, which are commonly used as a standard. Specifically, the PI values were between 18% and 22% lower than the Arduini curves. This discrepancy suggests that using the standard Arduini curves could lead to inaccurate assessments of placental health in the Chilean population and potentially in other populations with similar characteristics.

How could implementing new, population-specific Pulsatility Index (PI) values impact the diagnosis of placental insufficiency?

Implementing new, population-specific Pulsatility Index (PI) values, such as those derived from the Chilean study, could significantly improve the accuracy of placental insufficiency diagnoses. By using reference ranges that are tailored to a specific population, healthcare providers can reduce the risk of underdiagnosis. The Chilean study suggests that adopting their new PI values could lead to a more accurate assessment of placental function, ensuring that expectant parents receive appropriate and timely interventions when needed.

What are the implications of the Chilean study's findings regarding the universality of medical guidelines for fetal monitoring, specifically concerning Doppler velocimetry?

The Chilean study challenges the assumption that medical guidelines for fetal monitoring, particularly those involving Doppler velocimetry of the umbilical artery, are universally applicable. The differences observed in Pulsatility Index (PI) values compared to the Arduini curves highlight the importance of considering population-specific factors when assessing fetal well-being. This suggests that a 'one-size-fits-all' approach may not be appropriate, and that ongoing research is needed to adapt and refine medical guidelines to ensure accurate and effective fetal monitoring across diverse populations. This also implies that incorporating time-averaged mean velocity in the process might be beneficial as the study showed the t/2 curves were similar to what has been previously reported.