Emerging research identifies embryonic heart rate patterns that may help predict pregnancy loss after IVF

New reference ranges for early embryonic heart rate could help physicians counsel patients earlier and more precisely about pregnancy loss risk after IVF.

BALTIMORE, MD, UNITED STATES, October 27, 2026 /EINPresswire.com/ -- A new study from US Fertility establishes reference ranges for embryonic heart rate (EHR) in early pregnancy following in vitro fertilization (IVF) and shows that certain heart rate patterns can help predict the likelihood of pregnancy loss. The findings were presented at the 82nd ASRM Scientific Congress & Expo.

This is the first study to establish early EHR reference ranges specifically for pregnancies conceived through IVF; prior research on EHR and pregnancy loss risk focused on unassisted conceptions. The large-scale retrospective analysis offers physicians a new, IVF-specific benchmark for a measurement already taken routinely during early pregnancy monitoring.

The study has received the ASRM In-Training Award for Research, the ASRM 2026 Early Pregnancy Special Interest Group Prize Paper, and the Society for Reproductive Endocrinology and Infertility (SREI) Prize Paper.

“Embryonic heart rate is something we already check during early pregnancy monitoring, so having reference ranges specific to IVF pregnancies gives us a new way to use information we’re already collecting,” shares Laura X. Zalles, M.D., lead author and Shady Grove Fertility (SGF) Fellow at the University of Colorado Anschutz School of Medicine. “Knowing which heart rate patterns carry higher or lower risk between 7 and 9 weeks can help us have more informed, more specific conversations with patients earlier in a pregnancy, rather than asking them to simply wait and see.”

The retrospective cohort study analyzed 54,395 singleton pregnancies from fresh and frozen embryo transfer cycles, with and without preimplantation genetic testing (PGT-A), across the US Fertility network between 2015 and 2024. Researchers measured EHR between 6 and 9 weeks’ gestational age and compared distributions between pregnancies that resulted in live birth and those that ended in clinical pregnancy loss.

Key findings include:

EHR was significantly lower among pregnancies that ended in loss at every gestational age studied (all p<0.0001).

Predictive accuracy for pregnancy loss was highest between 7 weeks 0 days and 7 weeks 5 days’ gestation (AUC 0.75), with lower accuracy at 6 weeks (AUC 0.66) and 8 weeks (AUC 0.65).

By 9 weeks’ gestation, EHR was no longer predictive of pregnancy outcome (AUC 0.50).

Between 7 weeks 0 days and 8 weeks 6 days, an EHR at or below the 10th percentile among losses had a positive predictive value of 96–100% for clinical pregnancy loss.

Higher embryonic heart rates (90th percentile among losses) had low positive predictive value for pregnancy loss.

“This research gives fertility specialists a practical, IVF-specific benchmark where one didn’t exist before,” says Cassandra Roeca, M.D., Research Director at Shady Grove Fertility and final author. “Because embryonic heart rate is already part of routine early pregnancy care, these reference ranges can be applied right away to support how we counsel and monitor patients during a stage of pregnancy that’s often filled with uncertainty.”

These reference ranges give fertility specialists an additional, IVF-specific data point for identifying pregnancies at higher risk of loss earlier in gestation, supporting more informed counseling and monitoring decisions during a period that is often highly anxious for patients.

Learn more about US Fertility’s Research Division, which conducts and publishes high-quality studies to advance the field of reproductive medicine and provide better, more effective care to infertility patients.

ABOUT US FERTILITY

US Fertility, the nation’s largest partnership of physician-owned and physician-led top-tier fertility practices and IVF laboratories, are united under a shared mission to deliver the joy of parenthood through advanced reproductive medicine and innovative science. To date, US Fertility practices and laboratories have helped more than 430,000 individuals and couples build their families using assisted reproductive technology. US Fertility supports over 200 physicians by leveraging collective expertise, driving innovation, and by providing advanced business and digital solutions that streamline and enhance the delivery of exceptional patient care. Together with a growing suite of life science services, US Fertility is expanding access to the highest quality reproductive health care across over 135 clinic locations and 35 IVF laboratories. https://www.usfertility.com

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US Fertility
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