By Elodie Vaz | Published on May 12,
2026 | 4 min read
The placenta is a temporary
yet essential organ for the proper progression of pregnancy. Acting as the
interface between mother and fetus, it ensures the gaseous, nutritional, and
hormonal exchanges necessary for embryonic development. Despite its central
role, however, clinical monitoring of the placenta remains indirect, relying
mainly on the assessment of fetal growth and certain physiological parameters.
This lack of direct observation limits a detailed understanding of its
functioning, even though placental dysfunction remains a major cause of
obstetric complications and stillbirths.
Previous studies had
already suggested the existence of localized placental contractions distinct
from traditional uterine contractions. However, their fundamental
characteristics and frequency remained poorly defined.
Characterizing
placental contractions
In a study published on
April 29, 2026, in PLOS One, a team from the University of Nottingham
sought to better understand these phenomena. The objective was to precisely
characterize placental contractions and determine their frequency in
physiological pregnancies, while distinguishing them from contractions of the
uterine wall.
As Dr. Louise Dewick
emphasized, “This research is essential for better understanding the precise
functioning of the placenta during pregnancy.”
MRI and artificial
intelligence serving observation
The researchers recruited
36 healthy pregnant women between 29 and 42 weeks of gestation. Each
participant underwent magnetic resonance imaging (MRI) for a duration ranging
from 15 to 32 minutes.
Data analysis relied on
an automated neural network capable of tracking, in real time, variations in
the volume, surface area, and morphology of both the placenta and uterus. This
approach made it possible to objectively assess contractile dynamics with unprecedented
precision.
Contractions observed
in 60% of cases
The results revealed that
placental contractions occur in at least 60% of the healthy pregnancies
studied. Their median frequency was approximately two episodes per hour, with
an average duration of 2.4 minutes.
Unlike uterine
contractions, placental contractions produced greater changes in placental
shape and lasted longer. All contractions observed—whether placental or
uterine—were associated with an increase in an MRI signal linked to the
presence of deoxygenated blood.
A key element of the
study was the identification of a morphological marker: the degree of placental
sphericity. The researchers demonstrated that this variation in shape could
help automatically distinguish placental contractions from uterine contractions.
Dr. Dewick explained:
“Using magnetic resonance imaging (MRI), we were able, for the first time, to
clearly characterize placental contractions. We showed that they occurred in at
least 60% of healthy pregnant participants, with an average frequency of two
contractions per hour lasting 2.4 minutes.”
New tools for
placental monitoring
Despite certain
limitations—notably the relatively small sample size and the short duration of
imaging sessions—this study provides fundamental insights into placental
physiology. It opens the way toward a better understanding of the contractile
mechanisms of this organ.
According to Professor
Penny Gowland, “Advances in MRI allow us to use imaging to precisely determine
what is happening inside a pregnant woman’s body […] they could also help
improve the screening of potential problems during pregnancy.”
These findings therefore
lay the groundwork for future studies comparing these contractions in
pathological conditions such as intrauterine growth restriction or
preeclampsia. Ultimately, identifying functional placental signatures could
transform screening and monitoring strategies for high-risk pregnancies.
Finally, as Amy Turnball
highlighted, this breakthrough was made possible through close
interdisciplinary collaboration: “What struck me most about this project was
working within an interdisciplinary team […] to make a completely unprecedented
discovery.” Such a collaborative approach may prove crucial in uncovering the
still largely unknown mechanisms of this vital organ.
Read next: Can
stress during pregnancy erase the benefits of exercise ?
About the Author – Elodie Vaz
Health journalist, CFPJ graduate (2023).
Élodie explores the marks diseases leave on bodies and, more broadly, on
human life. A registered nurse since 2010, she spent twelve years at patients’
bedsides before exchanging her stethoscope for a notebook. She now investigates
the links between environment and health, convinced that the vitality of life
cannot be reduced to that of humans
