Exposure to 'Safer' Plastic Additive During Pregnancy Linked to Smaller Birth Size

NEW YORK, Oct. 13, 2026 /PRNewswire/ -- A chemical used to make plastic more flexible, once introduced as a safer substitute for older additives now known to be harmful, may itself also be harmful, slowing babies' growth in the womb, a new study shows.

A growing body of evidence has tied phthalates—substances used to make everyday products, such as food packaging, medical devices, and toys—to increased risk of premature birth, infertility, and other health concerns. In response, plastics manufacturers have begun replacing phthalates with newer chemicals, including diisononyl cyclohexane-1,2-dicarboxylate (DINCH).

Led by NYU Langone Health researchers, the analysis of 6,617 pregnancies linked higher levels of DINCH in the urine of pregnant women to lighter and smaller newborns. Every tenfold increase in exposure to DINCH resulted in a 27-gram reduction in newborn birth weight.

"Our findings suggest that a chemical promoted as a safer replacement for phthalates and other plasticizers may affect how babies grow in the womb," said study lead author Leonardo Trasande, MD, MPP, the Jim G. Hendrick, MD, Professor of Pediatrics at NYU Grossman School of Medicine. "Even small differences in birth size can matter because fetal growth problems can raise the risk for heart disease, learning difficulties, obesity, and other issues that can echo into adolescence and adulthood."

Laboratory studies in animals and human cells suggest that when DINCH breaks down in the body, its by-products can interfere with hormones that guide fetal development and trigger inflammation that may affect how nutrients and oxygen reach the baby. Together, these effects may contribute to pregnancy problems such as reduced fetal growth, high blood pressure during pregnancy, and early labor, said Dr. Trasande, who is also a professor in the Department of Population Health. A small analysis in pregnant women undergoing fertility treatment also linked higher DINCH exposure to an increased chance of preterm birth, a finding not seen in the current report.  

The new study, which published online Oct. 4 in the journal Environment International, is among the largest to date to examine how DINCH may impact pregnancy and birth size. It is also the first to measure the chemical at different times during pregnancy, the researchers said.

For the investigation, the nationwide group of scientists used data from the Environmental Influences on Child Health Outcomes program, which tracks families' health from pregnancy through childhood. Participants came from many different racial, ethnic, and economic backgrounds across the United States, making the results more representative of the nation than those from past studies.

Urine samples were tested for three DINCH breakdown products. Some participants had more than one sample, allowing the researchers to track exposure across different trimesters. The team then reviewed medical records to see each baby's birth weight and length. The analysis also accounted for other factors known to affect birth size, such as the mother's age, education, and number of previous pregnancies.

According to the results, between 50 percent and 70 percent of pregnant women in the study had measurable levels of a DINCH by-product in their urine.

Babies whose mothers had higher levels of DINCH in their urine were more likely to be classified as "small for gestational age," a term physicians use when a newborn's weight falls below the 10th percentile for babies born at the same stage of pregnancy.

Boys had greater differences in birth length, while girls were more likely to be small for their gestational age. DINCH exposure during the third trimester of pregnancy was more strongly tied to lower birth weight for gestational age than exposure in earlier trimesters.

In addition, mothers who were Hispanic or had lower levels of education were more likely to have children affected by DINCH, which the authors said raises concerns about disparities in exposure and health impacts.

"These results underscore the need for stronger oversight of chemicals used in food packaging and other household products by requiring they be tested before they are introduced to the market, instead of after they are connected to health concerns," said Dr. Trasande. "The global plastics treaty now under negotiation at the United Nations offers a key opportunity to establish such policies."

In the meantime, families who are concerned about plastic additives can talk with their healthcare providers and consider steps that may reduce exposure, added Dr. Trasande, who is also director of NYU Grossman School of Medicine's Division of Environmental Pediatrics and Center for the Investigation of Environmental Hazards.

The study authors next plan to examine other plasticizers being used as alternatives for phthalates and to study in more detail how DINCH may slow fetal growth.

The researchers cautioned that the analysis cannot prove that DINCH exposure directly causes smaller birth size.

Funding for the study was provided by the National Institutes of Health's Environmental Influences on Childhood Health Outcomes (ECHO) program.

Dr. Trasande is a member of the advisory boards of Ahimsa, the Food Packaging Forum Foundation, Function Health, and the Children's Environmental Health Network and is a member of the scientific advisory board of Exposome Intelligence. He represents the Endocrine Society as an Observer of the Plastics Treaty and advises countries and nongovernmental organizations about health effects of plastics. These relationships are being managed in accordance with the policies and procedures of NYU Langone.

Along with Dr. Trasande, Taylor Etzel, PhD, at Johns Hopkins University served as study senior author. Another NYU Langone researcher involved in the study was Mrudula Naidu, MS, MPH. Other study co-investigators include Morgan Nelson, MS, at RTI International; Akram Alshawabkeh, PhD, at Northeastern University; Emily Barrett, PhD, at Rutgers University; Jessie Buckley, PhD, at Johns Hopkins University; Dana Dabelea, MD, at the University of Colorado Anschutz; Anne Dunlop, MD, at Emory University; Julie Herbstman, PhD, at Columbia University; John Meeker, PhD, at the University of Michigan; Craig Newschaffer, PhD, at Penn State University; Amy Padula, PhD, at the University of California, San Francisco; Megan Romano, PhD, at Dartmouth College; Douglas Ruden, PhD, at Wayne State University; Sheela Sathyanarayana, MD, at the University of Washington; Susan Schantz, PhD, at the University of Illinois at Urbana Champaign; and Anne Starling, PhD, at the University of North Carolina at Chapel Hill.

About NYU Langone Health
NYU Langone Health is a fully integrated health system that consistently achieves the best patient outcomes through a rigorous focus on quality that has resulted in some of the lowest mortality rates in the nation. Vizient Inc. has ranked NYU Langone No. 1 out of 122 comprehensive academic medical centers across the nation five years in a row, and it continues to have the most No. 1– and top 10–ranked specialties among medical centers in the United States, according to U.S. News & World Report. NYU Langone offers a comprehensive range of medical services with one high standard of care across seven inpatient locations, its Perlmutter Cancer Center, and more than 400 outpatient locations in the New York City area and Florida. The system also includes two tuition-free medical schools, in Manhattan and on Long Island, and a vast research enterprise.

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SOURCE NYU Grossman School of Medicine and NYU Langone Health