Glyphosate, the chemical used in Roundup and other popular weed killers, is the most-used herbicide in the world—and new PROTECT research suggests glyphosate exposure may contribute to higher rates of preterm birth.

In a paper published in the May 2021 issue of Environmental Health Perspectives, PROTECT researchers presented the results of their investigation into the impacts of glyphosate and its degradation byproduct aminomethylphosphonic acid (AMPA) on preterm birth. Because glyphosate is not metabolized by the human body, it is possible to measure in urine. Researchers analyzed urine samples taken during the first and third visits of the PROTECT cohort, around 16-20 and 24-28 weeks respectively. They found no correlation between gestational age at birth and glyphosate concentrations in urine at the earlier visit, but the rates of preterm birth were significantly higher for women with higher glyphosate concentrations at the third visit.

This study builds on prior research in PROTECT that has suggested pesticide exposure could be a key factor in the risk of preterm birth. Shi Dong, a former trainee with the Data Management and Analysis Core, developed a machine learning approach to select features that were correlated with preterm birth in the PROTECT cohort. This approach highlighted pesticides exposure as a potential risk factor for preterm birth.

PROTECT co-investigator Dr. John Meeker (Project 1) was inspired to look at glyphosate in particular during a trip to Puerto Rico in May 2019. While he and other PROTECT researchers traveled the island to speak with health professionals at our partner clinics, he spotted an advertisement for a glyphosate product along the side of the road. When his team investigated the scientific literature, they found that very little research had been done in the area of glyphosate exposure and birth outcomes.

Given the widespread use of glyphosate in both residential and major agriculture settings, the public health implications of this study are profound. Preterm birth is the leading cause of infant mortality in the US, and is associated with many other health risks, some of them lifelong. For the PROTECT team, the next steps will be to investigate the mechanisms by which glyphosate may induce preterm birth, as well as looking at larger sample sizes and comparing with other populations in the US.