MRI scans reveal how the placenta contracts during pregnancy

Scientists at the University of Nottingham used MRI (magnetic resonance imaging) to distinguish between placental and uterine contractions, giving new insights about the placental health of pregnant women.  

Importantly, characterising healthy placental contractions may allow earlier identification of placental dysfunction and stillbirth risk. 

“We want to see whether they [placental contractions] are different in compromised placentas,” said Amy Turnbull, a physicist from the interdisciplinary research team. She explained that abnormal contractions could be early signs of pregnancy complications such as preeclampsia or foetal growth restriction. 

Dynamic MRI scans are a non-invasive way of observing highly detailed images of organs and tissues inside the body in real time. Using a wide bore MRI scanner, which has a larger chamber than a standard scanner, the team scanned 36 healthy women who were between 29-42 weeks pregnant. 

In at least 60% of the women, placental contractions occurred approximately twice an hour and lasted for an average of 2.4 minutes. 

Although a healthy placenta is vital for successful childbirth, little is known about the functioning of this important organ. “The placenta physically changes shape… they [the uterus and placenta] exhibit very different behaviour so we’re treating them as separate entities,” said Turnbull.  

Previous focus on uterine contractions, which involve the contraction of the whole uterus, may have led to the placenta being overlooked. For example, contractions during pregnancy are often assumed to be Braxton Hicks contractions, where the uterus tightens and relaxes as the body ‘practices’ for labour.  

This changed after a 2020 study – UoN researchers identified a phenomenon where the placenta and uterine wall contracted independently from the rest of the uterus. These contractions facilitated and controlled the flow of blood through the placenta and foetus, which is important for oxygenation and the removal of waste products.  

“This is an exciting time for interdisciplinary science,” Turnbull pointed out. “We have physicists, such as myself, biologists that look at the physiology, computer scientists doing segmentations of our images and mathematical modelling, and engineers making the technology. I think it’s really great to see everyone coming together for one application.” 

By Marina Milsum, July 18, 2026.

Edited by Kazuma Oura.