A growing body of evidence suggests the products we use daily may be quietly influencing pregnancy outcomes.
Published: June 2025
Imagine a world where the air we breathe, the food we package, and the products we use daily could silently increase the risk of early childbirth. For decades, the causes of preterm birth—delivery before 37 weeks of pregnancy—have puzzled scientists and clinicians alike. While genetic and socioeconomic factors play roles, a compelling new area of science is uncovering how environmental chemicals influence this complex equation. Recent research is now revealing the biological mechanisms through which these everyday exposures may be contributing to a global health challenge that affects 1 in 10 pregnancies worldwide.
Preterm birth is not merely a statistic; it is the leading cause of death globally among children under five and is linked to lifelong consequences for survivors, including cerebral palsy, respiratory distress syndrome, and long-term noncommunicable disease risks. The startling reality is that approximately 10% of preterm births worldwide may be attributable to fine particulate matter (PM2.5) exposure alone4 .
Scientists now recognize that certain environmental contaminants can disrupt delicate biological processes essential for maintaining pregnancy. The most significant chemical groups under investigation include:
Phthalates—used to soften plastics in food packaging, vinyl flooring, and personal care products—and bisphenol A (BPA) found in can linings and receipts.
PFAS (per- and polyfluoroalkyl substances), also known as "forever chemicals," used in non-stick cookware and stain-resistant fabrics.
Including both contemporary-use and banned organochlorine pesticides like DDT that persist in the environment.
What makes these chemicals particularly concerning is their pervasive presence in our environment and bodies. Studies show that phthalate metabolites are detected in more than 96% of pregnant women6 , while PFAS compounds routinely appear in serum samples across the globe, regardless of regulatory actions.
The journey from conception to birth requires precise biological coordination. Environmental chemicals can interfere with this process through several key mechanisms, primarily inflammation, oxidative stress, and endocrine disruption1 .
The female reproductive system is particularly vulnerable to inflammatory triggers. When the body perceives chemical irritants, it may mount an immune response that inadvertently targets reproductive tissues.
A groundbreaking 2025 study using a sophisticated Feto-Maternal Interface Organ-On-Chip (FMi-OOC) model demonstrated how four environmental pollutants—DDT, BPA, PBDE-47, and PFOA—triggered increased production of pro-inflammatory cytokines including IL-6, IL-8, GM-CSF, and TNF-α after exposure2 .
Many environmental chemicals function as endocrine disruptors by mimicking or blocking natural hormones. During pregnancy, precisely timed hormonal signals maintain uterine quiescence until the appropriate time for delivery.
PFAS compounds, for instance, have been shown to directly interfere with progesterone signaling in human endometrial cells8 . Progesterone is essential for maintaining pregnancy by preventing uterine contractions and supporting the endometrial lining.
Heavy metals like lead and cadmium induce oxidative stress in placental tissues by generating free radicals that damage cellular structures8 . The placenta normally acts as a "gatekeeper" between mother and fetus, but these metals can cross this barrier with relative ease.
Once in placental tissues, they catalyze reactions that produce reactive oxygen species (ROS), leading to damage of DNA, membrane lipids, and essential enzymes.
Increased cytokines trigger labor
Hormone signaling interference
Cellular damage from free radicals
Delivery before 37 weeks
To understand how scientists are untangling these complex relationships, let's examine a crucial 2025 study that investigated the connection between PFAS exposure and preterm birth.
This nested case-control study, conducted in Shanghai, China, involved 177 preterm birth cases and 531 matched controls5 . Researchers analyzed blood samples collected from pregnant women around 9 weeks of gestation, measuring seven different PFAS compounds using sophisticated ultrahigh-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS).
The research team employed multiple statistical approaches to account for the real-world reality that humans are exposed to chemical mixtures, not single compounds in isolation.
The results revealed that both individual and mixed PFAS exposures were significantly associated with increased preterm birth risk. Three compounds emerged as primary contributors: perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), and perfluoroundecanoic acid (PFUnDA).
| PFAS Compound | Primary Uses | Contribution to Preterm Birth Risk |
|---|---|---|
| PFOA | Non-stick cookware, waterproof fabrics | Highest risk contributor |
| PFNA | Food packaging, stain-resistant coatings | Significant contributor |
| PFUnDA | Grease-resistant paper, firefighting foam | Notable contributor |
The study further discovered that these associations were subtype-specific and sex-specific. The risk was more pronounced in cases of iatrogenic preterm birth (medically induced due to complications) compared to spontaneous preterm birth, and stronger associations were observed in pregnant women carrying male fetuses5 .
| Risk Category | Level of Association | Possible Explanation |
|---|---|---|
| Iatrogenic PTB | Higher | PFAS may contribute to placental complications necessitating early delivery |
| Spontaneous PTB | Lower | -- |
| Male fetuses | Higher | Potential sex-specific vulnerability to chemical disruption |
| Female fetuses | Lower | -- |
Understanding how environmental chemicals influence preterm birth requires sophisticated tools that can detect minute chemical concentrations and unravel complex biological pathways.
| Research Tool | Function | Application Example |
|---|---|---|
| Liquid chromatography-tandem mass spectrometry (LC-MS/MS) | Precisely measures chemical concentrations in biological samples | Quantifying phthalate metabolites in urine at minimal concentrations5 |
| Organ-on-a-Chip technology | Mimics human organ systems for toxicity testing without human subjects | Studying inflammatory responses in fetal membranes to chemical exposure2 |
| Silicone wristbands | Passive samplers that capture environmental chemical exposures | Monitoring pesticide exposure in pregnant women across different geographic regions3 |
| Weighted quantile sum (WQS) regression | Statistical method to evaluate effects of chemical mixtures | Identifying most harmful PFAS combinations in relation to preterm birth5 |
| Metabolomics | Comprehensive analysis of small molecules in biological systems | Identifying metabolic disruptions linking air pollution to preterm birth4 |
The Emory University study on air pollution exemplifies how these tools are advancing the field. Researchers analyzed blood samples from 330 pregnant women, identifying two specific substances—cortexolone and lysoPE(20:3)—as key players in the relationship between short-term air pollution exposure and elevated risk of early births4 . This metabolomic approach revealed disruptions in protein digestion and absorption pathways vital to fetal development, offering new potential targets for intervention.
While the scientific evidence linking environmental chemicals to preterm birth grows, so does the potential for action. Research indicates that reducing the mixture of phthalate metabolite levels by 50% could prevent preterm births by 12% on average6 . The economic implications are substantial—the preventable cases of phthalate-induced preterm birth in the United States alone carry estimated costs between $1.63-8.14 billion annually7 .
Selecting fresh, home-cooked foods over processed foods packaged in plastic can reduce phthalate exposure.
Choosing fragrance-free products or those labeled "phthalate-free" reduces chemical load.
Using air purification systems in areas with high pollution can reduce particulate matter exposure.
However, the responsibility extends beyond individual behavior. The findings underscore the need for evidence-based chemical policy reforms that prioritize protection of vulnerable populations, particularly during critical windows of development like pregnancy.
The science linking environmental chemicals to preterm birth has evolved from simple correlation to sophisticated mechanistic understanding. We now know that multiple chemical classes can disrupt delicate biological processes through inflammation, oxidative stress, and endocrine disruption, creating conditions that predispose to early childbirth.
As Dr. Donghai Liang from Emory University aptly notes, "As an air pollution scientist, I do not think air pollution is going away anytime soon. Even at lower levels, we continue to see harmful health effects"4 . This reality underscores the urgency of translating these scientific insights into protective measures—both clinical interventions for at-risk pregnancies and regulatory policies that reduce overall chemical exposures.
The silent crisis of environmental chemical contributions to preterm birth may be invisible to the eye, but it is increasingly visible through the lens of science. By continuing to support this vital research and implement its findings, we move closer to a world where every pregnancy has the opportunity to reach its full term.