10% of Premature Births Linked to Phthalate Exposure In Utero

Earlier this week, researchers revealed that approximately 10% of premature births in the United States are linked to prenatal phthalate exposure in a study published in the Lancet Planetary Health.

Using data from the US National Institutes of Health Environmental Influences on Child Health Outcomes (ECHO) program, the researchers assessed the correlation between 20 phthalate metabolites with birth outcomes, including gestational age at birth, birthweight, birth length, and birthweight for gestational age z-scores.

The data was evaluated between 1998 and 2022, with researchers estimating how many adverse birth outcomes and their associated costs can be linked to phthalate exposure by evaluating urinary phthalate measurements during pregnancy. Evaluating 13 cohorts in the ECHO Program, the researchers gathered insights from over 5,000 mother–child dyads.

Exposure data revealed that mothers in the highest percentile of phthalate exposure were 50% more likely to have a premature delivery than those in the lowest exposure percentile. Additional insights revealed that, in 2018, 10% of all premature births were linked to phthalate exposure, suggesting that reducing exposure during pregnancy can help improve the probability of carrying a pregnancy to term.

Among the 20 phthalate metabolites evaluated in this study, the researchers noted that the following had the strongest association with adverse birth outcomes: phthalic acid, di-isodecyl phthalate (DiDP), di-n-octyl phthalate (DnOP), and di-isononyl phthalate (DiNP).

The data revealed that phthalic acid was associated with a 2.71 times greater probability of preterm birth. Additionally, the risk of preterm birth with DiNP exposure was 2.25 times greater than without. Comparatively, a 1.69- and 2.90-times increased risk of preterm birth was linked with DiDP and DnOP exposure, respectively.

“In a large, diverse sample of US births, exposure to DEHP, DiDP, DiNP, and DnOP were associated with decreased gestational age and increased risk of preterm birth, suggesting substantial opportunities for prevention. This finding suggests the adverse consequences of substitution of DEHP with chemically similar phthalates and the need to regulate chemicals with similar properties as a class,” concluded researchers in the study.

This data — combined with recent insights published by the CDC earlier this year, which revealed a rise in preterm births between 2014 and 2022 — emphasizes the need to address environmental factors that may impact gestational age.