Can microplastics from plastic baby bottles end up in the placenta and affect birth weight?

What's actually in it

Plastic baby bottles, food containers, and packaging shed tiny particles called microplastics. These fragments are smaller than a grain of sand and come from polypropylene, polyethylene, and polystyrene. You swallow them with food and water every day. During pregnancy, these particles can cross from the mother's blood into the placenta.

What the research says

A 2026 study in Ecotoxicol Environ Saf collected placentas from women who had just given birth and analyzed them for microplastic contamination. Every single placenta contained microplastics. The researchers then compared the types and amounts of plastic particles to each baby's measurements at birth.

Babies whose placentas contained more microplastics showed differences in birth weight and body proportions. The study found a measurable link between specific plastic types and changes in how the baby grew during the final weeks of pregnancy.

The most common plastics found were the same ones used in food packaging and baby products. Polypropylene, which is in most baby bottles and sippy cups, was one of the top materials detected.

The researchers point out that the placenta is supposed to be a filter that protects the baby. Finding plastic particles inside it means those particles are getting past the body's defenses. And they're not just sitting there: the study found they're associated with real changes in fetal growth.