Microplastics and pregnancy: what to know

What does the evidence say about microplastics during pregnancy?

1. A rapid systematic review found human evidence on microplastics and pregnancy outcomes is still too limited to classify one way or another, rating the certainty for both birth outcomes and gestational age as low or very low, based on only three observational human studies. 1
2. That same review reported one human study found a statistically significant correlation between the amount of microplastic found in the placenta and a lower birth weight, though the review stresses this comes from limited, early-stage research rather than an established finding. 1
3. In a mouse study, pregnant animals given polyethylene micro- and nanoplastic particles through their drinking water didn't show restricted fetal growth, but did show a 43 percent increase in umbilical artery blood flow and measurable widening of the umbilical artery, changes the researchers said could pose a risk to placental function if they occur in people too. 2
4. A review of microplastics in food found some of the highest single-source exposures come from steeping a plastic tea bag, which can release around 10 billion microplastic and several billion nanoplastic particles into one cup of tea, and from using plastic cutting boards, which can shed tens of millions of particles a year. 3
5. A review comparing tap and bottled water found microplastic concentrations were consistently higher in bottled water than in tap water, partly because municipal water filtration and purification systems remove up to 90 percent of microplastics, and the authors recommended tap water as the lower-exposure choice. 4

Is microplastics safe in each trimester?

• First trimester. There's no first-trimester-specific microplastics research to point to. If you want to lower exposure early on, swapping bottled water for tap water and using glass or stainless containers for hot food are easy, low-cost habits to start now.
• Second trimester. The evidence at this stage still comes mainly from animal studies and small human samples rather than large pregnancy cohorts, so the guidance stays the same: reduce avoidable sources like hot liquids stored in plastic and single-use bottles where it's easy to do.
• Third trimester. No research points to a late-pregnancy-specific concern. Continuing the same simple habits, tap water, less reheated food in plastic, and fewer disposable cups, covers the exposure routes researchers have identified so far.