Now even the very air that pregnant women breathe can be just as dangerous as inhaling cigarette smoke, as pollutants in the air keep rising to alarming levels.
A new study, led by Dr. Xiaohui Xu, an assistant professor of epidemiology in the colleges of Public Health and Health Professions and Medicine of University of Florida, on a grant from the National Institute of Environmental Health Sciences, tracked the birth registry of Jacksonville, Florida to investigate the possible connection between air pollutants, such as nitrogen oxide, sulfur dioxide from industrial plants, carbon monoxide from vehicles, and some particulates, to the risk of high blood pressure in pregnant women.
The researchers studied the medical data of 22,000 pregnant women in the area that had given birth within the years 2004 and 2005. The sample excluded those with chronic hypertension, those who have had given premature birth prior to the data gathering, and those whose babies were born with complications.
The researchers also used the data gathered by the Environmental Protection Agency daily on the air pollutions levels in the area, and gauged how much pollution the 22,000 pregnant women were exposed to during the duration of their pregnancy. The researchers also considered other risk factors such as socioeconomic status and exposure to smoking.
The researchers have found that of the 22,000 pregnant women studied, 4.7 percent developed hypertension while still pregnant. Those who were exposed to air pollution during their first and second trimester of pregnancy had a higher risk of developing high blood pressure and other hypertensive disorders.
Hypertensive disorders in pregnant women such as gestational hypertension, preeclampsia and eclampsia are known to affect about 10 percent of pregnancies. These conditions eventually result in complications during the pregnancy and the delivery, and which are associated with increased morbidity and mortality, and even premature delivery.
"Fetal development is very sensitive to environmental factors," said Dr. Xu. "That is why we wanted to do this research.
However, the study was not able to make a definite conclusion on whether it's exposure during early pregnancy or late pregnancy that was more likely to raise a woman's risk for high blood pressure and other hypertensive conditions.
Avoiding air pollution, though, is not easy, either for pregnant women or for the rest of the human population. The key is for communities and government to be more aggressive in controlling air pollution, not just for the health of pregnant women but for everyone.
The researchers have said that they plan to conduct further studies on this throughout the state of Florida, and will include other health conditions in pregnant women that could be affected and caused by pollution.
"We are trying to look at several outcomes," said Dr. Xu. "We also want to look at preterm delivery and low birth-weight and find out what the effects of breathing contaminated air are on fetal development."