The Chemicals Inside Us: What a Landmark Pregnancy Study Reveals — and Why Personal Choices Aren’t Enough
A new study published in JAMA Network Open gives us deeper understanding at chemical exposure during pregnancy in the United States — and its findings are concerning and demand attention from parents, healthcare providers, and policymakers alike.
The study, considered one of the largest of its kind, looked at more than 5,000 mother-child pairs born between 2000 and 2021. Researchers analyzed 5,318 urine samples, mostly collected during the second trimester, testing for 113 substances across 10 common chemical classes:
fungicides and herbicides,
insecticides,
halogenated phenols,
organophosphate esters,
benzophenones,
bisphenols,
parabens,
antimicrobials,
phthalates and alternative plasticizers, and
polycyclic aromatic hydrocarbons.
What They Found
Of the 113 chemicals tested, 110 were detected in at least one sample.
The average participant had 45 different chemicals or metabolites present — and one sample contained as many as 64.
A total of 43 of the 113 analytes were detected in 50% or more of samples.
Chemicals frequently found in air pollution, PAH and BPA replacements were linked to lower birth rates
The chemicals aren’t rare industrial chemicals. They are found in food, water, air pollution, personal care products, fragrances, and other household objects.
The Specific Chemicals Linked to Harm
Of the 113 substances tested, a subset are most concerning in terms of health effects on the baby :
phthalate: Higher levels of diisononyl phthalate (DiNP) were associated with delivery approximately 0.6 days earlier on average and a 16% higher risk of preterm birth. Detection of phthalic acid was associated with delivery about one day earlier and a 48% higher risk of preterm birth.
Two halogenated phenols, benzophenone-8, bisphenol F, and several polycyclic aromatic hydrocarbons (PAHs) were associated with lower birth weight for gestational age. Specifically, 1- and 9-hydroxyphenanthrene were associated with a significantly lower birth weight-for-gestational-age z score.
(A difference of less than a day may not sound significant for one pregnancy. But when millions of pregnancies share similar exposures, even a small average shift can contribute to meaningfully more babies being born early — with consequences that can follow a child for life.)
MAJOR ISSUES THIS STUDY HIGHLIGHTS
1. The Problem of Regrettable Substitution
One the most troubling finding in the study isn’t what the chemicals are — it’s which chemicals they are.
In 2017, the U.S. Consumer Product Safety Commission permanently banned or severely limited eight common phthalates in children’s toys and products due to documented health harms. some of the phthalates linked to earlier births in this study are ones that were introduced specifically as alternatives to those older, banned phthalates.
This is what researchers and toxicologists call regrettable substitution: a chemical is phased out due to health concerns, and a structurally similar compound is brought in to replace it — without adequate safety data, without labeling
requirements, and often with the same biological mechanism of harm.
We see this pattern repeat across chemical classes:
• Phthalates: The originals were restricted. Their replacements — alternative plasticizers like DINCH and DEHTP — are now showing up in pregnant women’s bodies and linked to preterm birth in this very study.
• Bisphenols: BPA was phased out following evidence of endocrine disruption. BPS, BPF, and BPAF have largely taken its place. Notably, bisphenol F was among the compounds associated with lower birth weight in this study — and early research suggests it shares BPA’s hormone-disrupting properties.
The “BPA-Free” label is perhaps the most visible example of this problem in consumer culture. It signals the removal of one chemical while obscuring the presence of its unstudied replacements.
Lack of regulation
Many of these chemicals are really hard to avoid, although apps like Toxwise can help significantly, most people in the general population do not know about this and do not known how to avoid them. Ob/gyn nor fertility specialists dont advice women on how to avoid chemicals either.
The ideal would be federal regulations that would regulate and assure harmful chemicals stay out of the marketplace.
“Pregnant people are at risk of chemical exposure through multiple sources, many of them beyond their control. Governments and companies need to do a better job of reducing harmful chemicals in everyday products and ensuring new chemicals are safe, which will lead to healthier children and families,” added co-author Tracey Woodruff of Stanford.
Reducing your personal toxic load — through cleaner food, products, and home environments — still matters. But this study makes clear that individual choices operate within a system that is not designed to protect us. The burden cannot fall on pregnant women alone.
It’s not just pregnant women
while the study focuses on pregnant women, the reality is that These chemicals are found in the general population and affect us all from children to adults.
What you can do
Currently, Republican senators are trying to rule back the only chemical regulation that exists in our country. It is by far not perfect, but these officials are trying to push it back to the 1970s when it was even less strict. ( back then asbestos wasn't even banned.!). you can call your senators and insist they push back. @Lindsay_Dahl has more details on how easy it is to do this including a script.
Do you know someone who is pregnant or thinking of becoming pregnant? Are you in this category? If so, talk to them about the importance of reducing their exposure to these chemicals and if they need help, tell them about the ToxWise app.... ( 20% off launch special only for a few more days) I specifically created it to help people reduce their exposure to these chemicals and you can specifically tell the app you are pregnant or thinking of becoming pregnant so that it focuses your journey in the app on the chemicals most important to avoid during pregnancy