Microplastics May Increase Preterm Birth Risk, Scientists Warn

Micro- and nanoplastic particles accumulate to higher concentrations in the placentae of infants born prematurely than those born at term. This is the conclusion of a team of U.S. researchers who analyzed the plastic content of 175 placentae following either preterm or term birth. "This hints at the possibility that the accumulation of plastics could be contributing to the risk and occurrence of preterm birth," said Kjersti Aagaard, maternal–fetal specialist professor at Boston Children's Hospital, in a statement. Microplastic (smaller than 5 millimeters in size) and nanoplastic (under 0.001 millimeters) pollution have become ubiquitous in the environment and can get into the very food we eat. Scientists are concerned about their impact on human health. Aagaard added: "This study adds to the growing body of evidence, ranging from heart disease to potentially stroke, that demonstrates a real risk from exposure to plastics on human health and disease."

In their study, the researchers analyzed 100 placentae which were collected at term, and 75 that were collected preterm—that is, after less than 37 weeks of pregnancy. Each placenta was examined using highly sensitive mass spectrometry, which allowed them to identify 12 different types of plastic pollution in the specimens, including polyethylene, polypropylene and polyurethane. "Advanced technology now enables us to accurately measure microplastics in ways we haven't been able to in the past," said Aagaard. The team discovered that the levels of micro- and nanoplastics were significantly higher in preterm placentas than term placentas—and also at much greater levels than previously measured in human blood. Based on this, the team believe that plastics likely accumulate in the placenta over the course of a pregnancy—and more so in the case of an ultimately preterm birth.

"The finding of higher placental concentrations among preterm births was surprising," said paper author and obstetrics and gynecology professor Enrico Barrozo of the Baylor College of Medicine in a statement. "It was counterintuitive to what you might expect if it was merely a by-product of the length of time of the pregnancy." Aagaard added: "In other words, a preterm delivery not only accumulated more microplastics and nanoplastics in its placenta relative to term, but did so at an earlier time point in the pregnancy." It is this fact, say the researchers, that suggests that micro- and nano-scale plastic pollution could be a factor in the causes of preterm birth. While the mechanism of action is unclear at present, the team wrote in their conference abstract that "micro and nanoplastic bioaccumulation may play a role in modulating inflammatory preterm birth." The full findings of the study were presented Thursday at the annual meeting of the Society for Maternal–Fetal Medicine in Denver, Colorado. Do you have a tip on a health story that Newsweek should be covering? Do you have a question about microplastics? Let us know via science@newsweek.com.

Reference

Barrozo, E. R., Garcia, M. A., Jr, M. D. J., Liu, R., Nihart, A., Castillo, E., Hayek, E. E., Gonzalez-Estrella, J., Showalter, L., Shope, C., Suter, M. A., Campen, M. J., & Aagaard, K. M. (2025). Elevated Micro- and Nanoplastics Detected in Preterm Human Placentae. Oral Concurrent Session 1 – Equity, Public Health, and Policy. SMFM 2025 Pregnancy Meeting, Denver, Colorado. https://doi.org/10.1002/pmf2.12004