Scientists link spontaneous miscarriages to three types of air pollutants

Air pollution released from the burning of fossil fuels may be linked to an increase in the number of miscarriages, a new study has found.

This research follows a separate review study which found that exposure to air pollution during pregnancy may be associated with a greater risk of children developing autism.

The new study examined exposure to particulate matter, sulfur dioxide and nitrogen dioxide in pregnant women during their first trimester.

These toxic chemicals are found throughout the US, but are especially 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 this data together with data on 770 pregnant women admitted to two of the city’s hospitals between 2018 and 2019.

Among them, 154 suffered a miscarriage, and the researchers found that a significant number of those who lost their babies were pregnant while air quality in Baoji was at its worst.

There are several theories about why air pollution can cause miscarriage, including disrupting pregnancy hormones, causing harmful inflammation in the mother, and negatively affecting fetal development.

Fine particulate matter, 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 for setting allowable levels.

Burning fossil fuels is one of the leading sources of all three of these pollutants. Long-term exposure to it can lead to lung disease, heart disease and premature death.

An overview of the latest literature was recently published in the magazine Brain medicine 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 from Yan’an University in China investigated whether these pollutants could affect the incidence of miscarriage in pregnant women.

Air quality in Baoji is generally considered poor but varies seasonally due to increased burning of coal for home heating in winter, the researchers said in their report.

As of November 12, the air quality index (AQI) in Baoji is 229, which is considered “very unhealthy,” according to the researchers. IQAir. By comparison, Los Angeles currently has an AQI of 18, which is considered “good.”

But both Los Angeles and Baoji share the same major pollutant: particulate matter.

These microscopic particles can travel deep into the lungs and cause tissue damage and inflammation.

The study found that women who were pregnant in spring and winter – when concentrations of certain air pollutants were higher in Baoji – were more likely to have miscarriages

The researchers analyzed air pollution data alongside data from 770 pregnant women admitted to the Obstetrics and Gynecology Department of Baoji Central Hospital and Baoji People’s Hospital between 2018 and 2019.

Of these 770 women aged 19 to 44, 154 had a miscarriage and 616 had full-term babies.

The researchers calculated the level of exposure to outdoor air pollution for each pregnant woman during their first trimester.

They published their findings in the journal Nature on Monday.

Their research found that those who were pregnant in spring and winter were more likely to miscarry than those who were pregnant in summer and fall, which could be good evidence of a link between fine particulate matter, sulfur dioxide, nitrogen dioxide and a miscarriage, they wrote. .

That’s because air quality monitoring data showed that concentrations of these pollutants were higher in spring and winter than in summer and autumn, because Baoji residents burn coal to heat their homes in the colder months.

The study found no link between ozone or inhalable particles and miscarriage.

These new findings are consistent with a 2016 study that found that exposure to nitrogen dioxide alone can increase the rate of miscarriage by 16 percent.

Experts have offered several explanations as to why air pollution can increase the risk of miscarriage.

Some suggest this is because these chemicals disrupt pregnancy hormones, while others point to their ability to cause harmful inflammation in pregnant women.

Other studies have found that air pollutants can affect fetal development and lead to low birth weight, premature birth, birth defects, abnormal fetal growth and neonatal death.

Research has also shown that air pollution can cause abnormal development of the placenta, which can lead to adverse pregnancy outcomes.

But there are many more risk factors for miscarriage, and not all of them are environmental factors such as pollution.

Age, history of miscarriage, vaginal microbiome, genetics and immune factors are known to influence the risk of miscarriage, the researchers wrote.

Their study evaluated these independently of air pollution exposure and found that occupation, number of previous deliveries and caesarean sections, last menstrual season, history of pregnancy complications and pregnancy comorbidities were significant risk factors for miscarriage.

Although this study has shown a remarkable link between three widespread air pollutants and miscarriages, breathing air pollution has not been found to cause miscarriages.

To further explore this association and a possible causal relationship, future studies will need to take into account indoor air pollution and use a much larger sample size of pregnant women, the researchers wrote.

And to find stronger evidence of causality, future studies should take a prospective approach: following mothers and the incidence of miscarriages during their pregnancies.