Air pollution released from burning fossil fuels may be linked to an increase in miscarriages, a new study has found.
This research comes on the heels of a separate review study that found that exposure to air pollution during pregnancy may be linked to an increased risk of children developing autism.
The new study investigated exposure to fine particulate matter, sulfur dioxide and nitrogen dioxide in pregnant women during the first trimester.
These toxic chemicals are found throughout the United States, but are particularly prevalent in cities such as Bakersfield and Los Angeles, California, Fairbanks, Alaska, and Phoenix, Arizona.
The researchers collected data from air quality monitoring stations in Baoji, a city in northwest China, recorded between 2017 and 2019.
They then analyzed these records along with data from 770 pregnant women who were admitted to two of the city’s hospitals between 2018 and 2019.
Among them, 154 suffered miscarriages and researchers found that a significant number of those who lost their babies were pregnant, while air quality was worse in Baoji.
There are several theories as to why air pollution can cause miscarriages, including disrupting pregnancy hormones, triggering harmful inflammation in the mother and negative effects on fetal development.
Researchers have discovered a link between three common air pollutants and miscarriages.
Fine particles, sulfur dioxide and nitrogen dioxide are three of the six “criterion” pollutants, so called because the Environmental Protection Agency (EPA) regulates them by developing criteria to establish allowable levels.
The burning of fossil fuels is one of the main sources of these three pollutants. Prolonged exposure to them can cause lung and heart disease and premature death.
Recently, a review of the latest literature published in the journal Brain medicine It found that people with a genetic predisposition to autism who were exposed to air pollution early in life were more likely to develop the condition than people exposed to less air pollution.
Researchers at Yan’an University in China investigated whether these pollutants could affect the incidence of miscarriages in pregnant women.
Air quality in Baoji is generally considered poor, but it varies seasonally due to increased burning of coal for home heating in winter, the researchers said in their report.
As of Nov. 12, the air quality index (AQI) in Baoji is 229, which is considered “very unhealthy,” according to IQAir. By comparison, Los Angeles currently has an AQI of 18, which is considered “good.”
But both Los Angeles and Baoji share the same main pollutant: fine particles.
These microscopic particles can travel deep into the lungs, causing tissue damage and inflammation.
The study found that women who were pregnant in spring and winter, when concentrations of certain air pollutants were highest in Baoji, suffered miscarriages more frequently.
The researchers analyzed air pollution records along with data from 770 pregnant women admitted to the Department of Obstetrics and Gynecology of Baoji Central Hospital and Baoji People’s Hospital between 2018 and 2019.
Of these 770 women, ages 19 to 44, 154 suffered miscarriages and 616 gave birth to full-term babies.
The researchers calculated each pregnant woman’s level of exposure to outdoor air pollution during the first trimester.
They published their findings in the journal. Nature on Mondays.
The study found that those who were pregnant in spring and winter had a higher incidence of miscarriages than those who were pregnant in summer and fall, which could be good evidence for a link between fine particles, sulfur dioxide, nitrogen dioxide and spontaneous abortion, they wrote. .
This is because air quality monitoring data revealed that concentrations of these pollutants were higher in spring and winter than in summer and autumn, as Baoji residents burn coal to heat their homes in the colder months. .
The study did not find a link between ozone or inhalable particles and miscarriage.
These new findings are in line with a 2016 study that found that nitrogen dioxide exposure alone can increase miscarriages by 16 percent.
Experts have proposed several explanations for why air pollution may increase the risk of miscarriage.
Some suggest it’s because these chemicals disrupt pregnancy hormones, while others point to their ability to trigger harmful inflammation in pregnant women.
Other studies have found that air pollutants can affect fetal development and cause low birth weight, premature birth, birth defects, abnormal fetal growth rate, and neonatal mortality.
Research has also found that air pollution can cause abnormal placental development that can lead to adverse pregnancy outcomes.
But there are many other risk factors for miscarriage, and not all of them are environmental factors like pollution.
Age, history of miscarriage, vaginal microbiome, genetics and immune factors are known to influence miscarriage risk, the researchers wrote.
Their study evaluated them independently of exposure to air pollution and found that occupation, number of previous deliveries and cesarean sections, last menstrual season, history of pregnancy complications, and pregnancy comorbidities were important risk factors for abortion spontaneous.
While this study has identified a notable link between three widespread air pollutants and miscarriages, it has not found that breathing air pollution causes miscarriages.
To further investigate this link and a possible causal relationship, future studies will need to take indoor air pollution into account and use a much larger sample of pregnant women, the researchers wrote.
And to look for stronger evidence of causality, future studies should take a prospective approach: tracking mothers and the incidence of miscarriages throughout their pregnancies.
