Illustration of a pregnant woman with a fetus, highlighting blood flow and antenatal care.

Antenatal Steroids: Are They Always a Safe Bet for Premature Babies?

Reese Marlowe in Health & Wellness December 2025 • 3 min read.

"A new study suggests that while antenatal corticosteroids can benefit some premature babies, they may pose risks for those with growth restrictions."

For women at risk of premature delivery, antenatal corticosteroids (ACS) are a standard treatment to help speed up the development of the baby's lungs. However, new research suggests that while ACS can be beneficial, it may not be a one-size-fits-all solution, especially for growth-restricted (GR) fetuses.

A study published in 'Ultraschall in Med' investigates how ACS affects blood flow and heart function in both appropriate for gestational age (AGA) and growth-restricted fetuses. The findings reveal that while ACS can improve some blood flow parameters, it may also lead to potential heart function issues in GR fetuses.

This article will delve into the key findings of this research, explore the implications for prenatal care, and offer guidance for parents and healthcare providers navigating the complexities of premature birth interventions.

Understanding the Study: ACS Impact on Fetal Cardiovascular Health

Illustration of a pregnant woman with a fetus, highlighting blood flow and antenatal care.

The study, led by Laura Marchi and colleagues, involved monitoring cardiovascular function in AGA and GR fetuses before and after ACS administration. Using Doppler ultrasound, researchers assessed various parameters, including:

Fetal-Placental Blood Flow: Measured via the umbilical artery (UA) pulsatility index (PI) and middle cerebral artery (MCA) PI.

Cardiac Function: Assessed through the ductus venosus (DV) PI, E/A wave ratios, and myocardial performance index (MPI).
Study Timeline: Measurements were taken before ACS, 24-48 hours after the first dose, and seven days after the second dose.

The researchers then compared the changes in these measurements to understand how ACS affects the cardiovascular systems of both AGA and GR fetuses.

Making Informed Decisions About Antenatal Steroids

While ACS remains a crucial tool in managing preterm births, this study highlights the importance of considering individual fetal conditions, especially in growth-restricted fetuses. Parents and healthcare providers should engage in thorough discussions about the potential risks and benefits of ACS, ensuring the best possible outcomes for both mother and child. Further research is needed to refine these findings and develop more targeted interventions for high-risk pregnancies.

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: 10.1055/a-0654-4824, Alternate LINK

Title: Cardiovascular Hemodynamic Changes After Antenatal Corticosteroids In Growth Restricted And Appropriate For Gestational Age Fetuses

Subject: Radiology, Nuclear Medicine and imaging

Journal: Ultraschall in der Medizin - European Journal of Ultrasound

Publisher: Georg Thieme Verlag KG

Authors: Laura Marchi, Lucia Pasquini, Ayten Elvan-Taspinar, Caterina Maddalena Bilardo

Published: 2018-10-26

Everything You Need To Know

What are antenatal corticosteroids, and why are they used in premature births?

Antenatal corticosteroids (ACS) are medications given to women at risk of premature delivery to help speed up the development of the baby's lungs. They are significant because they can improve lung function in premature babies, potentially reducing respiratory distress syndrome and other complications associated with early birth. The implications involve weighing the benefits of improved lung development against potential risks, especially in growth-restricted fetuses.

What does it mean if a fetus is described as growth-restricted, and why is it important to consider this when using antenatal steroids?

Growth restriction (GR) in fetuses refers to a condition where the baby is smaller than expected for their gestational age. This is important because GR fetuses may respond differently to interventions like ACS compared to appropriate-for-gestational-age (AGA) fetuses. The cardiovascular systems of GR fetuses might be more vulnerable to the effects of ACS, potentially leading to heart function issues. It highlights the need for individualized assessment before administering ACS.

What are UA PI and MCA PI, and why are they measured when studying the effects of antenatal steroids?

The umbilical artery (UA) pulsatility index (PI) and middle cerebral artery (MCA) PI are measurements used to assess blood flow in the fetal-placental circulation. These measurements are significant because they help healthcare providers understand how well the fetus is receiving oxygen and nutrients from the placenta. Changes in UA PI and MCA PI after ACS administration can indicate how the medication is affecting blood flow dynamics, which is crucial for fetal well-being. Doppler ultrasound is used to measure this blood flow.

What are DV PI, E/A wave ratios, and MPI, and what do they tell us about the heart health of a fetus?

Ductus venosus (DV) PI, E/A wave ratios, and myocardial performance index (MPI) are parameters used to assess cardiac function in fetuses. DV PI reflects blood flow through a vessel in the fetal liver, E/A wave ratios indicate the filling of the heart's ventricles, and MPI measures overall heart performance. Monitoring these parameters is important because they can reveal how ACS affects the fetal heart. Changes in these values, especially in growth-restricted fetuses, can signal potential cardiovascular risks associated with ACS.

What is Doppler ultrasound, and how is it helpful in monitoring babies before they are born?

Doppler ultrasound is a non-invasive imaging technique used to assess blood flow and cardiovascular function in fetuses. It is important because it allows healthcare providers to monitor the effects of interventions like ACS on the fetal cardiovascular system without exposing the fetus to radiation. Doppler ultrasound provides valuable information about fetal-placental blood flow (via UA PI and MCA PI) and cardiac function (via DV PI, E/A wave ratios, and MPI), aiding in informed decision-making regarding prenatal care.