Publication Q&A: A Comprehensive Assessment of Associations Between Prenatal Phthalate Exposure and the Placental Transcriptomic Landscape

A Comprehensive Assessment of Associations Between Prenatal Phthalate Exposure and the Placental Transcriptomic Landscape

Alison G. Paquette, James MacDonald, Samantha Lapehn, Theo Bammler, Laken Kruger, Drew B. Day, Nathan D. Price, Christine Loftus, Kurunthachalam Kannan, Carmen Marsit, W. Alex Mason, Nicole R. Bush, Kaja Z. LeWinn, Daniel A. Enquobahrie, Bhagwat Prasad, Catherine J. Karr, and Sheela Sathyanarayana

Published in Environmental Health Perspectives, September 2021

What are the significant findings in this paper?

In this study, exposure to several phthalates (chemicals found in a wide variety of products, such as soap, shampoo, children’s toys, building materials and food packaging) during pregnancy was associated with higher or lower placental gene expression in 38 genes. Gene expression is a measure of how DNA is converted into proteins, which are the building blocks of cells and play critical roles in development.

The placenta is a very important organ that is also critical for proper infant growth and development. We also identified differences in gene expression that were significant only in males or only in female infants, indicating that phthalates may impact placental function differently between the two sexes. We studied the biological pathways that these genes were involved in and found 27 specific pathways that were associated with prenatal phthalate exposure. These pathways were involved in the generation of key molecular building blocks important for the developing infant.

It is important to note that this study involved participants who were between 16 and 40 years old, primarily Black (57.6% of study participants), had relatively healthy pregnancies and were from a lower-income geographic area in Memphis, Tennessee.

What does this research tell us that we didn’t know before?

This research tells us that exposure to certain phthalate chemicals during pregnancy is related to gene expression in placentas. This is important because gene expression may impact the developing baby. For example, we found that higher levels of phthalates measured in urine during the third trimester were related to decreased placental expression of genes that are 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 long-term impacts on infant health.

The research also tells us that specific phthalates may impact placental function differently between the male and female sexes.

What are the broad implications of this research? (i.e., how might this research lead to better ways to treat/prevent/diagnose?)

The placenta is a very important organ for pregnancy researchers because it can reveal a lot about the developing fetus. 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 the baby or cause changes in fetal growth and development. Identifying how chemicals like phthalates alter placental function may help us to understand the associations between phthalate exposure and some pregnancy complications.

This, in turn, could lead to the development of preventative measures to reduce or eliminate exposure to materials containing potentially harmful phthalates during pregnancy in order to avoid pregnancy complications and changes in fetal growth and development.

What are the next steps and long-term goals for this research?

More work needs to be done to better understand how these changes in gene expression in the placenta relate to placental function and specifically how this impacts the developing baby.

Together, our research team is studying how changes during pregnancy may alter placental function and fetal growth development. We will study changes in the placenta related to other pregnancy complications like preterm birth within the same population of pregnant women involved in this study. We will also map out how phthalates may cause these changes in gene expression using new tools and technologies.

Additionally, we need to follow this work up with studies involving other populations and investigate how these changes in placental function impact infant and childhood health.

Any other specific information we should know about this paper?

It is important to recognize that study participants who are primarily Black (as in this study) constitute a population that has traditionally been underrepresented in this type of research.