What We're Learning About Pre-term Birth and Herbicides

Namely, what is Glyphosate and why do I care so much about it?

Let me just start with the fact that I know this is a very controversial topic. The literature is mixed on the consumption of genetically modified foods, and today I want to skirt a bit around the issues of the foods themselves, and talk a bit more about the herbicide most commonly known as Roundup, that was borne of the same folks who developed GM foods.

I'm from the states, which means that I've been grappling with the knowledge of having GM foods in the grocery stores for years. In fact, I remember in 2012 when I first learned about it, which means I spent the majority of my life thus far completely oblivious to what big agriculture was doing to my food... that's one way to take the autonomy away from us.

Glyphosate was patented and brought to market in the US in 1974, and its use stayed fairly modest for its first couple of decades. That changed sharply in 1996, when genetically modified "Roundup Ready" soy, corn, and cotton were introduced, crops engineered to survive being sprayed with glyphosate directly, which meant farmers could apply it throughout the growing season rather than just once before planting. Use in the US climbed steeply from there.

The UK's relationship with glyphosate took a different path. It arrived in British farming in the 1980s, when Scottish farmers began spraying it on wheat just before harvest to dry the crop faster in the country's damp conditions, a practice called pre-harvest desiccation. The UK doesn't grow the glyphosate-tolerant GM crops common in the US, so here it's used mainly to clear fields of weeds before planting, and again to dry crops just ahead of harvest. It's now licensed for use on wheat, barley, oats, peas, beans, and oilseed rape, with cereal crops like wheat and barley making up the largest share of UK use.

Given how embedded glyphosate is in both countries' food systems, it's easy to see why researchers keep circling back to its effects on human health, and in my case here, during pregnancy.

The Study

Researchers at NYU Grossman School of Medicine followed a group of pregnant women (1,450 of them!) in New York City and looked at whether glyphosate exposure during pregnancy was linked to preterm birth (this meaning delivery before 37 weeks). It's one of the largest studies of its kind in humans so far, and it measured glyphosate at more than one point in pregnancy rather than just once, which lets researchers see the impact of both timing of exposure (ie: preconception, first, second or third trimester), and total exposure.

The researchers tracked pregnant women and measured glyphosate levels in their urine at different points in pregnancy. Overall, about 7 percent of the births in the study were preterm, in line with national averages. But when they looked specifically at women with higher glyphosate levels measured between 18 and 25 weeks of pregnancy, the odds of preterm birth were about 35 percent higher.

The effect was even more pronounced for what's called spontaneous preterm birth, meaning labor that starts naturally rather than being medically induced. In that group, higher glyphosate levels were linked to roughly double the odds of an early birth.

Why does this distinction matter to me? It points toward the body's own labor-triggering pathways, rather than a separate medical complication that led a doctor to intervene early. Lab studies in animals and cells have suggested glyphosate may activate inflammatory processes that are part of how labor gets started, which offers a plausible biological story behind the numbers (this is still not the entire picture yet, though).

Why the mid-pregnancy window is interesting:

One of the more thought-provoking parts of this study is that the association showed up specifically during that 18 to 25 week window, not evenly across all of pregnancy. The body goes through real physiological shifts at different stages, and it may simply be more sensitive to certain exposures at certain times. The exact mechanism is still being studied, but it's a helpful reminder that "exposure" isn't one flat risk, but that timing within pregnancy may matter as well.

What this study can't tell us

It's worth saying clearly: this is an association (aka a correlation study), not proof of cause and effect. The study's own senior author was careful to note that these findings can't establish that glyphosate directly causes preterm birth. The next step for this research team is digging into the actual biological mechanisms, to understand how glyphosate might influence fetal development and the timing of birth. I will keep my eyes out for future literature to make sure I am well informed of the most up to date information when it comes out.

What you can actually do with this

One of my biggest goals is not to become a fear-mongerer with all of this information. It's just a truth that glyphosate is genuinely widespread in our environment, and no single choice will eliminate exposure entirely. That said, it's so important to look to what we CAN do, instead of sitting in our resignation and anger about things we are really unable to control. Because of that, lets look at a few reasonable, low-effort steps that we can take to meaningfully reduce our exposure to this herbicide:

• Wash produce thoroughly before eating, even when it looks clean

• Choose organic grains and produce where it's accessible and affordable to you, since these tend to show lower residue levels

• Bring questions about environmental exposures to your prenatal visits, your care team can help you weigh what's practical for your own life

  
  

The study's lead author was candid that individual choices help but aren't a full solution, and that broader regulatory attention to reproductive health is part of the bigger picture here too. I think that's the right way to hold this research: useful information to act on where you reasonably can, without carrying the weight of a problem that's bigger than what we can taken on as individuals.

My takeaway

We know that pre-term birth can have some consequences for newborns, including breathing difficulties to longer term developmental effects. This is why research like this really matters and is really exciting to see. This study adds a meaningful piece to a growing body of evidence on glyphosate and reproductive health, and it does so with more rigour than most of what's come before it. Make the small changes that are realistic for you, and know that this is an area of medicine that's actively getting more attention. And hopefully, the more eyes we have on it, the more change will take place at a governmental level to control the harm we are potentially doing.

Reference: Herrera T, Fragoman F, Ghassabian A, et al. Associations of Glyphosate Exposure in Pregnancy with Preterm Birth: a Longitudinal Birth Cohort Study. Environmental Pollution. 2026;128775. doi:10.1016/j.envpol.2026.128775