A study published in a May 2021 issue of Environmental Health Perspectives revealed a link between the popular (and controversial) weedkiller glyphosate and an increased risk of preterm births. The study, conducted by University of Michigan researchers, aimed to show the effects of exposure to glyphosate and aminomethylphosphonic acid (AMPA)—which is an environmental degradation of glyphosate—on pregnant women.

Researchers gathered urine samples from pregnant women and tested them for prenatal exposure to the substances, which are the main ingredients in the Roundup weedkiller. Ultimately, the researchers found that women who indicated exposure to glyphosate-based herbicides showed a significantly higher chance of experiencing premature labor.

Women exposed to the weedkiller during their third trimester suffered the greatest risk for preterm births, according to the study. Women who experienced exposure during their first trimester did not indicate the same risk.

Origin of the Glyphosate-Preterm Birth Study

According to Michigan News, the idea for this study came to John Meeker, professor of environmental health sciences and senior associate dean for research at the U-M School of Public Health, several years ago as he and some research collaborators were visiting clinics around Puerto Rico’s northern coast. In the lush green surroundings of the area, Meeker noticed a sign advertising a popular weedkiller.

Meeker had established a pregnancy and birth cohort called PROTECT over a decade earlier. The cohort’s mission was to study possible environmental factors that could be contributing to increasing preterm births among Puerto Rican women. Meeker suggested to his team that the group should measure levels of glyphosate in the PROTECT study’s participants of pregnant women.

Knowing about glyphosate’s global ubiquity and the fact that it had already been established as negatively impacting human health, Meeker sensed that the substance could add a significant factor to the cohort’s already researched environmental factors, including maternal stress, chemicals, and metals.

Understanding the Study’s Methodology

The PROTECT cohort chose to use urine samples to measure the glyphosate levels because this substance is not largely metabolized in mammals’ bodies. They further decided to check for AMPA in the samples. As a degradation product of glyphosate, it takes months for AMPA to degrade.

The urine samples of 247 PROTECT study participants was measured in the first trimester and at the third trimester of their pregnancies.

The researchers compared participants’ preterm births with the concentrations of glyphosate and AMPA in their urine samples at each stage of pregnancy. The comparisons revealed that participants who showed higher concentration levels of the substances during their third trimesters had higher odds of premature labor and preterm births. In contrast, the participants who had high levels of the substances during their first trimesters showed no association with preterm births.

Consistent With Earlier Research

Although the University of Michigan study is one of the first scientific explorations of the effect of glyphosate exposures on preterm birth, the research results are consistent with a small study conducted in Indiana.

The Indiana study was published in the March 2018 issue of Environmental Health. It too connected exposure to glyphosate with abbreviated gestation times.

Sara Stephens is a freelance writer who has developed a hefty portfolio of work across several industries, with a strong emphasis on law, technology, and marketing. Her work has appeared in the New York Times, as well as various technology and consumer publications, both print and online. Sara also works as a freelance book editor, having developed and edited manuscripts for bestselling and novice authors alike, and as a verbal strategist for a Miami branding consultancy.