A study has found microplastic and nanoplastic pollution to be significantly higher in placentas from premature births than in those from full-term births.
The levels were much higher than previously detected in blood, suggesting the tiny plastic particles were accumulating in the placenta. But the higher average levels found in the shorter pregnancies were a “big surprise” for the researchers, as longer terms could be expected to lead to more accumulation.
Preterm birth is the leading cause of infant death worldwide, and the reasons for about two-thirds of all preterm births were unknown, said Dr Enrico Barrozo, of Baylor College of Medicine in Texas, US. The established link between air pollution and millions of premature births had spurred the research team to investigate plastic pollution.
The new study only demonstrates an association between microplastics and premature births. Further research is needed in cell cultures and animal models to determine if the link is causal. Microplastics are known to cause inflammation in human cells, and inflammation is one of the factors that prompts the start of labour.
Microplastics, broken down from plastic waste, have polluted the entire planet from the summit of Mount Everest to the deepest oceans. People are already known to consume the tiny particles via food, water and by breathing them in.
Microplastics were first detected in placentas in 2020 and have also been found in semen, breast milk, brains, livers and bone marrow, indicating profuse contamination of people’s bodies. The impact on human health is little known, but microplastics have been linked to strokes and heart attacks.
“Our study hints at the possibility that the accumulation of plastics could be contributing to the occurrence of preterm birth,” said Prof Kjersti Aagaard, at Boston children’s hospital in the US. “Combined with other recent research, this study adds to the growing body of evidence that demonstrates a real risk from exposure to plastics on human health and disease.”
The research was presented on Thursday at the Society for Maternal-Fetal Medicine’s annual meeting in Denver, and has been submitted to an academic journal. The researchers analysed 100 placentas from full-term births (37.2 weeks, on average) and 75 from preterm births (34 weeks), all from the Houston area.
Analysis with highly sensitive mass spectrometry found 203 micrograms of plastic per gram of tissue (µg/g) in the premature placentas – more than 50% higher than the 130µg/g in the full-term placentas.
Twelve types of plastic were detected, with the most significant differences between the full and preterm birth placentas being for PET, as used in plastic bottles, PVC, polyurethane and polycarbonate.
Some mothers are at higher risk of preterm births, due to their age, ethnicity and socioeconomic status. But a strong link between the plastic particles and premature birth remained even when these factors were taken into account.
“This study showed an association and not causation,” said Barrozo. “But I think it is important to increase people’s awareness of microplastics and their associations with potential human health effects.”
The effectiveness of actions to cut people’s exposure to microplastics also needed urgent study, he said. “Those interventions need to be studied in order to show that there’s a benefit to avoiding these plastics.”