Small unseen particles in air pollution inhaled by pregnant women may damage the cardiovascular system of the unborn baby and delay its growth and development, according to a study unveiled Monday.
Researchers from Rutgers University in the US found that early first trimester and late third trimester were critical windows during which pollutants most affect the mother's and foetus' cardiovascular systems.
"These findings suggest that pregnant women, women of child-bearing years who may be pregnant and those undergoing fertility treatments should avoid areas known for high air pollution or stay inside on high-smog days to reduce their exposure," said Phoebe Stapleton, an assistant professor at Rutgers University.
"Pregnant women should also consider monitoring their indoor air quality," Stapleton said in a statement.
What a mother inhales affects her circulatory system, which is constantly adapting to supply adequate blood flow to the foetus as it grows, according to the study published in the journal Cardiovascular Toxicology.
Exposure to these pollutants can constrict blood vessels, restricting blood flow to the uterus and depriving the foetus of oxygen and nutrients, which can result in delayed growth and development.
It can also lead to common pregnancy complications, such as intrauterine growth restriction.
The study looked at how the circulatory systems of pregnant rats and their foetuses were affected by a single exposure to nanosized titanium dioxide aerosols -- a surrogate for particles found in typical air pollution -- during their first, second and third trimesters.
The results were compared to pregnant rats that were exposed only to high-efficiency filtered air.
The researchers found that exposures to pollutants early in gestation significantly impact a foetus' circulatory system, specifically the main artery and the umbilical vein.
Later exposure had the most impact on foetal size since the restricted blood flow from the mother deprives the foetus of nutrients in this final stage.
In non-pregnant animals, even a single exposure to these nanoparticles has been linked to impaired function of the arteries in the uterus.
The study found that one exposure late in pregnancy can restrict maternal and foetal blood flow, which can continue to affect the child into adulthood.