Researchers examine association of preterm birth and chemicals in flame-retardant fabrics

A Kaiser Permanente Southern California study of 3,500 women showed that pregnant women with high levels of PDBE-47, a chemical used in flame-retardant fabrics, were at increased risk of giving birth early in the pregnancy.

The study, “Women with high plasma levels of PBDE-47 are at increased risk of preterm birth” was published recently in the Journal of Perinatal Medicine.

Polybromated Diphenyl Ethers (PBDEs) are one of the most prevalent organic pollutants due to their widespread use during the past 40 years as flame retardants, especially in the United States and Canada. As a result, North Americans have the highest blood and breast milk concentrations of PBDEs anywhere in the world. PBDEs are present in the blood of almost all pregnant women.

Researchers in this study examined the chemical PBDE-47, just one of the many compounds found in PBDE, because it is the most abundant chemical compound in the environment and in plasma and breast-milk samples.

This new research showed that compared with women with low concentrations of PBDE-47 in their blood during the first trimester of pregnancy, those with high concentrations had:

  • more than double the risk of preterm indicated birth, which are births in which the baby is deliberately delivered by labor induction or cesarean, and
  • nearly double the risk of spontaneous preterm birth.

“North Americans, in general, and Californians, in particular, have the highest levels of exposure to flame retardants anywhere in the world,” said Darios Getahun, MD, PhD, a research scientist with the Department of Research & Evaluation and senior author on the research. “We know that these chemicals can affect the thyroid hormone, which is very important in pregnancy and in the development of the placenta. This may be why the high concentrations of this chemical can lead to an increased risk of preterm births.”

High levels of PBDEs had previously been associated with lower birth weight, but the effects on preterm birth had been less clear.

For this research, pregnant women were recruited when they initiated prenatal care at Kaiser Permanente West Los Angeles and Kaiser Permanente San Diego medical centers from June 1, 2013 to May 31, 2017. Plasma samples from women whose pregnancies ended preterm and a random sample of women who delivered at term were analyzed for PBDE-47 and thyroid stimulating hormone (TSH).

Nearly all samples collected in the first trimester had detectable levels of PBDE-47. However, patients with PBDE levels in the top quarter of the samples were at significantly increased risk for both spontaneous and indicated preterm births.

“This research gives us better understanding about the potential effect of PBDE-47 on preterm birth,” Dr. Getahun said. “Although the chemicals from flame retardants are all around us here in Southern California,” Dr. Getahun said, “one thing women can do is replace furniture that has flame retardant materials.”

Kaiser Permanente took the bold step of discontinuing purchases of furniture containing flame retardants in 2014. You can read that story here: