Phthalates are man-made chemicals that are commonly found in plastics, solvents, and personal care products like perfumes, nail polishes, soaps, and hair sprays. Because they are found in so many household products, people can be exposed to them often. Unfortunately, there is little research on how exposure to phthalates can affect a pregnant woman’s health and the health of the developing baby. Investigating how exposures to phthalates affect the placenta, an organ that delivers oxygen and nutrients to the baby, can reveal more about the relationship between these chemical exposures and infant health.
To explore this research gap, Alison Paquette, PhD of Seattle Children’s Research Institute and the ECHO Pathways research team examined the association between phthalate exposure in the second and third trimester and gene expression in the placenta. This information provides insight into how phthalates may affect different placental functions.
To conduct this research, the team gathered urine samples from 760 women enrolled in the Conditions Affecting Neurocognitive Development and Learning in Early Childhood (CANDLE) study in Shelby County, TN. Their placentas were also collected after giving birth. Participants were between 16-40 years old, with relatively healthy pregnancies, and a majority were Black.
The team measured the levels of 16 different phthalates in each urine sample provided during the mother’s second and third trimesters and analyzed the levels of expression for every gene in the placenta after giving birth. Gene expression is a measure of how DNA is converted into proteins, which perform a variety of important cellular functions and play critical roles in development. For each gene, the researchers investigated the link between that gene’s expression and phthalate levels during pregnancy. The researchers used this information to analyze which biological pathways in the placenta are potentially affected by phthalate exposure.
The study found that several phthalates were associated with higher or lower placental gene expression for 38 genes. The team also identified some changes in gene expression that were only significant in male or female infants, indicating that phthalates may alter placental function differently for the different sexes. The team also found 27 specific biological pathways that may have been affected by phthalate exposure, including pathways essential to infant development. For example, the team found phthalate exposure was linked with decreased expression of the genes involved in the generation of fatty acids, which are essential building blocks for organ development. Changes in generating these fatty acids may impact how the fetus grows, particularly the brain, which may have a long-term impact on the child’s health.
“Placental gene expression is an important marker that can tell us if the placenta is performing all its normal jobs correctly. If the placenta is not functioning correctly, it may lead to pregnancy complications that threaten the health of both the mother and baby, or cause changes in fetal growth and development,” said Paquette. “By identifying how chemicals like phthalates alter placental function, it may help us understand the associations between phthalate exposure and some pregnancy complications.”
Moving forward, the research team will study how changes in the placenta are associated with other pregnancy complications, such as preterm birth, within the same population of women. Additional research, paired with new tools and technology, will also help them map out how phthalates may cause these changes in gene expression.