Submitted by aml95 on Thu, 12/03/2026 - 20:47
New research led by scientists from the University of Cambridge has uncovered a striking link between a mother’s body mass index (BMI) and the levels of key placental proteins circulating in her blood during early pregnancy.
This collaborative study led by Nooria Atta, Professor Stephen O'Rahilly and colleagues from the IMS-MRL and Professor Catherine Aiken and others from the Department of Obstetrics and Gynaecology, builds on earlier work investigating nausea and vomiting in pregnancy in the Cambridge Baby Growth Study (CBGS). During that research, researchers noticed an unexpected pattern - levels of the placental hormone GDF15 in maternal blood were highest in women with the lowest pre-pregnancy BMI and lowest in women with the highest BMI.
They further explored whether the same relationship existed for other pregnancy-related proteins using samples from three independent studies CBGS, Children of the 90s (Bristol University) and 'The Pregnancy Outcome Prediction Study (POPS). They found that maternal BMI showed the same inverse association with three additional biomarkers—hCG, PAPP-A, and AFP—which are produced by the placenta or fetus and transferred into the maternal circulation. The pattern was consistent across the entire BMI range and could not be explained simply by dilution in larger blood volumes. Notably, maternal height—an important determinant of blood volume—showed little relationship with these protein levels.
These findings which were published in Placenta, suggest that maternal fat stores themselves influence how much of these proteins enter the maternal bloodstream in early pregnancy. Recent imaging studies undertaken by Dutch scientists reporting that women with lower BMI tend to have greater utero-placental vascular volume support the idea that maternal energy stores may influence the degree of placental invasion and the size of the materno–fetal interface. Impaired early placental development is strongly related to the risk of pre-eclampsia, a common and serious disorder, which is more common in pregnancies of women living with obesity.
Stephen O'Rahilly commented:
"This simple observational study may be pointing to something profound relating to how healthy rates of early fetal growth can occur in the face of a wide variety of calories available to the pregnant mother. If so, then the uterine lining of lean women encourages the development of a very invasive placenta which extracts as much nutrition as possible from the mother to ensure the fetus can grow at an adequate rate. In contrast, the uterine lining of an obese woman restrains the extent of early placental invasion to prevent too many calories being transferred to the growing fetus, thus reducing the mechanical risks associated with trying to deliver too large a baby.
Understanding the molecular signals that allow the uterus to sense maternal energy status could open new avenues for studying how maternal nutritional state influences fetal growth and the risk of disorders like pre-eclampsia."
This research was supported by the Medical Research Council (MRC) and the NIHR Cambridge Biomedical Research Centre.
Reference: Nooria Atta, Cleo Pike, Tabitha Wishlade, Ulla Sovio, Clive J. Petry, Sam Lockhart, Ken K. Ong, Ieuan A. Hughes, Sandra F. Goodburn, Gordon Smith, Catherine Aiken, Stephen O'Rahilly. The inverse association between circulatory placental biomarkers in early pregnancy and maternal body mass index, Placenta, Volume 177, 2026, Pages 36-43, https://doi.org/10.1016/j.placenta.2026.03.004
