A new study has given insights into placental contractions during pregnancy, using MRI imaging to show how placental and uterine contractions can be distinguished, and how frequent and long lasting they are.
This new research builds on previous work conducted by researchers from the University of Nottingham’s School of Physics and Astronomy and School of Medicine, that described a completely new phenomenon of placental contractions. These involve the placenta and the part of the uterine wall to which it is attached and are not the same as the well-known ‘Braxton Hicks’ contractions in which the entire uterus contracts in preparation for labour.
Using a wide bore scanner at the University of Nottingham’s Sir Peter Mansfield Imaging Centre, the team scanned 36 women who were between 29 and 42 weeks pregnant and characterised placental contractions. This is part of a larger multidisciplinary study with the goal of finding markers of placental stillbirth risk. The results have been published today in the journal PLOS one.
Louise Dewick from the University of Nottingham’s School of Medicine is one of the lead authors on the study, she explains: “This research is vital in furthering our understanding of exactly how the placenta works in pregnancy. Using MRI imaging we have, for the first time, clearly characterised placental contractions. We have shown that they occurred in at least 60% of our healthy pregnant participants with an average frequency of 2 per hour lasting for 2.4 minutes. These occurred more frequently than uterine contractions and are associated with a larger increase in the surface area of the uterine wall not covered by the placenta.”
The placenta is vital in the transfer of the right amount of nutrition and oxygen from the mother to the baby. Any disturbance to the flow of blood carrying oxygen and vital nutrients could restrict fetal growth, and if placental circulation is compromised this can also lead to pre-eclampsia and stillbirth.
However, methods of detecting developing placental compromise are largely indirect, relating to the growth and activity levels of the fetus. Ultrasound assessment of fetal growth may be inaccurate or falsely reassuring and maternal perception of fetal movements is subjective. This has led to a focus on finding new reliable methods to detect placental dysfunction.
Advances in MRI imaging allowed the researchers to explore markers of placental function, in particular parameters that depend on multiple aspects of tissue structure including movement, but specifically concentration and distribution of deoxygenated blood. This is known to increase in conditions associated with placental dysfunction, like pre-eclampsia.
Amy Turnbull, co-lead author on the research from the School of Physics and Astronomy said: “It’s been really exciting to be able to use MRI alongside clinicians to conduct this research and reveal something totally new about how the placenta works. These findings have also informed the design of further research into the characteristics of placental contractions in compromised pregnancies where we hope to see if there are associations between the rate, duration or nature of placental contractions with other markers of placental or fetal wellbeing or with adverse pregnancy outcomes.”
Professor Penny Gowland, University of Nottingham School of Physics and Astronomy said: “We can now use MRI imaging to pinpoint exactly what is happening inside a woman’s body during pregnancy. These new insights build on previous work and provide important markers for healthy placental function and are opening up new areas of research.”
The findings from this work have also informed the development of a wearable device by the Faculty of Engineering which will allow the monitoring of placental contractions in varying maternal positions and over a longer time period to further improve understanding of this phenomenon.
PLOS One
Experimental study
People
Placental contractions in uncomplicated pregnancies
29-Apr-2026