BPA Replacements Block the Enzyme That Protects Fetuses

The placenta has a protective enzyme called 11β-HSD2. Its job: convert active cortisol into inactive cortisone before it reaches the fetus. Too much cortisol during fetal development causes lasting harm to brain development, stress responses, and metabolism. A 2026 study in the Journal of Steroid Biochemistry and Molecular Biology found that BPA derivatives (the chemicals used to replace BPA) inhibit this protective enzyme.

What the Study Found

Researchers tested six BPA derivatives and found them all to be inhibitors of 11β-HSD2. The most potent was a compound called BPH, with an inhibitory concentration of just 1.26 µM in human cells. That's within the range of real-world exposure levels. The researchers also found that human 11β-HSD2 was more sensitive to these chemicals than the rat version, meaning the human data matters more than animal studies might suggest.

The researchers conclude that BPA derivatives are "novel chemical probes" and warn about their endocrine-disrupting potential, "particularly in prenatal contexts where placental 11β-HSD2 safeguards fetal development."

What "BPA-Free" Actually Means

When manufacturers replaced BPA, they swapped in structurally similar chemicals. BPS, BPF, BPAF, and now a range of other BPA derivatives. Many of these chemicals were assumed safer because they hadn't been studied the same way BPA had. Studies like this one are catching up. The pattern repeats: the replacement has the same mechanism of harm as the original.

Avoiding all bisphenol variants means avoiding plastic food contact materials entirely. Glass, stainless steel, and borosilicate glass don't contain bisphenols. Browse non-toxic baby products made with materials that don't use bisphenol chemistry, and non-toxic kitchen alternatives for pregnancy-safe cooking and storage.

Source: Ren X, Shi L, Chen X, Tang Y, Ying Y (2026). J Steroid Biochem Mol Biol.