Phthalates may increase risk of preterm births.

A new study conducted in Mexico provides evidence that women with higher exposure to phthalates may be more at risk of delivering premature babies.


Women with higher exposure to phthalates during their third trimester of pregnancy were up to four times as likely to have their babies early.

This is the first human study to investigate associations between exposure to phthalates and preterm birth rates. Other studies examining the link between urinary phthalate markers and gestational age at birth have found mixed results.

Early births are of concern because they are associated with long-term health problems and are the leading cause of neonatal mortality in the United States, accounting for more than one third of infant deaths. While causes are elusive, environmental factors may contribute to preterm births. It is hypothesized that phthalates may act as endocrine disruptors, mimicing the action of hormones in the body.

Phthalates soften plastics and act as solvents in a wide range of industrial and consumer applications. Personal care products (perfumes, lotions and cosmetics), medical devices, coatings in some pharmaceuticals, food packaging and vinyl (flooring, construction products) may contain phthalates. Human exposure is common because of their widespread use.

Thirty women who delivered preterm babies (less than 37 weeks’ gestation) and 30 others who delivered full term babies participated in this study. Researchers collected urine during participants' third trimester of pregnancy and measured 11 phthalate residues.

The study reported a 2 to 4-fold increased likelihood of preterm births in women whose total phthalate exposure was above – versus below – the median. Phthalate residues were detected in all samples and their concentrations were generally similar to those reported for US women.

This is the first study on the topic. These results thus need to be confirmed in other populations.