Pollution's Impact: Pregnancy And Birth Complications

Air pollution is a pressing issue that affects people worldwide, and its impact on pregnancy outcomes has been a growing area of research. Studies have shown that exposure to air pollution during pregnancy can have significant adverse effects on both mothers and their babies. The consequences include low birth weight, preterm birth, asthma, autism, and even fertility problems.

With increasing evidence of the detrimental effects of air pollution on prenatal health, it is crucial to understand the risks and take preventive measures to protect pregnant women and their unborn children. This includes monitoring air quality, staying indoors when necessary, using air purifiers, and advocating for better air quality through policy changes.

This topic highlights the urgent need to address air pollution and its impact on pregnancy, as it can have long-term health consequences for both mothers and their children.

Low birth weight

Air pollution has been linked to low birth weight in various studies. A baby weighing under five pounds and eight ounces is considered to have a low birth weight. On average, one in every 12 babies in America is born underweight. While there are a variety of reasons for this, exposure to air pollution during pregnancy is speculated to be one of them.

Evidence

A study in Beijing—one of the world's most polluted cities—found that babies born to women in their eighth month of pregnancy during the 2008 Olympics were, on average, 0.8 ounces heavier than babies born during the same calendar months in previous years. This is notable because Beijing was mandated to lower emissions and improve air quality during the Olympic period.

A 2019 study in Guangdong, China, found that the increase in the risk of low birth weight was associated with PM2.5, PM10, NO2, and O3 in the first and last months of pregnancy.

A 2018 study in London, which has high levels of air pollution, found small black spots, thought to be tiny carbon particles from the air, trapped inside cells in placentas collected from new mothers. This provided evidence that particles inhaled by a pregnant woman can move through the lungs, into the bloodstream, and into the placenta.

A 2015 meta-analysis conducted in Iran reported that the prevalence of preterm labour in the country was 9.2%. Evidence suggests that maternal exposure to air pollution during pregnancy, especially in the first trimester, is associated with an increased risk of preterm labour.

A 2007 study in Connecticut and Massachusetts found that an interquartile increase in gestational exposure to NO2, CO, PM10, and PM2.5 lowered birth weight by 8.9 g, 16.2 g, 8.2 g, and 14.7 g, respectively.

Effects by Race

Some studies suggest that the effects of air pollution on birth weight may be higher for infants of black mothers than those of white mothers. A 2001 study in six Northeastern U.S. cities found a stronger relationship between CO exposure and low birth weight for African-American infants than for white infants.

Critical Periods of Exposure

The first and third trimesters appear to be critical periods of exposure. A 2019 study in Guangdong, China, found that the increase in the risk of low birth weight was associated with PM2.5, PM10, NO2, and O3 in the first and last months of pregnancy.

A 2004 study in Seoul, South Korea, found that the risk of low birth weight increased as mothers were exposed to higher levels of pollutants in the first trimester.

Recommendations

To reduce the risk of low birth weight, pregnant women are recommended to reduce or avoid exposure to air pollution, especially in the early and late stages of pregnancy.

Preterm birth

Air pollution has been linked to preterm birth in numerous studies. According to a study by The Stockholm Environment Institute (SEI) at the University of York, nearly three million babies are born prematurely each year due to air pollution. That means 18% of all annual preterm births have been connected to exposure to particulate matter pollution.

Risk Factors

• Location: Women who live in areas with high levels of air pollution are more likely to deliver prematurely. A study of births in Vancouver, British Columbia, Canada, found an association between sulfur dioxide air pollution and preterm birth.
• Timing of Exposure: The timing of exposure to air pollution during pregnancy may impact the risk of preterm birth. Some studies suggest that exposure during the first trimester may be more critical, while others indicate that exposure later in pregnancy could be more significant.
• Air Pollutants: Specific air pollutants such as sulfur dioxide, nitrogen dioxide, and particulate matter (PM2.5 and PM10) have been linked to an increased risk of preterm birth.
• Individual Factors: Certain individual factors, such as respiratory problems, asthma, allergies, and chronic conditions, may increase the risk of preterm birth when exposed to air pollution.

Protecting Yourself and Your Baby

• Monitor Air Quality: Check your area's air quality index (AQI) regularly to stay informed about the pollution levels and potential health risks.
• Limit Outdoor Activities: Avoid spending extended periods outside when the air quality is poor, especially if you have respiratory issues.
• Smoke-Free Environments: Ban smoking in your home and car, and avoid places where people smoke. If you smoke, quitting is the best option for your health and your baby's well-being.
• Air Purifiers: Consider investing in air purifiers for your home to reduce indoor air pollution and create a healthier environment for you and your baby.

Asthma and autism risk

Asthma and autism are two conditions that have been linked to air pollution exposure during pregnancy. Research has shown that air pollution can negatively affect unborn babies, and in recent years, the body of evidence supporting this claim has grown.

Asthma Risk

During pregnancy, asthma can cause preeclampsia, a condition that results in elevated blood pressure and decreased liver and kidney function. Asthma can also cause poor growth, premature birth, and low birth weight in babies if left untreated. Additionally, exposure to air pollution can increase a child's chances of developing asthma later in life, as particulate matter pollution can breach the placenta.

Autism Risk

An alarming Harvard study revealed that women exposed to high levels of particulate matter pollution during their third trimester were twice as likely to give birth to a child with autism, especially if they lived near a highway. The study also found that exposure to pollution earlier in pregnancy did not increase the risk of autism. A separate study from southern Sweden found that exposure to local, source-specific ambient air pollution during pregnancy was associated with an increased risk of autism in children.

Miscarriages and fertility problems

Miscarriages and fertility issues have been linked to pollution in several studies. Exposure to air pollution during pregnancy, especially in the first 1,000 days of life, can be detrimental to the health of the fetus and newborn.

Miscarriages

Miscarriages, or spontaneous abortions, are one of the worst outcomes of pregnancy. Exposure to air pollution, particularly ozone and fine particles, may increase the risk of early pregnancy loss. A study by the National Institutes of Health followed 501 couples trying to conceive and found that couples with higher exposure to ozone were 12% more likely to experience early pregnancy loss, while those exposed to particulate matter were 13% more likely. The researchers suggested that this could be due to increased inflammation of the placenta and oxidative stress, which can impair fetal development.

Other studies have found links between exposure to air pollutants and first-trimester pregnancy loss. For example, a study in London, a city with high levels of air pollution, found that placentas from new mothers contained small black spots, believed to be carbon particles from the air, trapped inside cells. Additionally, a study in Michigan and Texas found that couples with higher exposure to air pollution experienced a higher risk of miscarriage before 18 weeks of pregnancy.

Fertility Problems

Air pollution has also been linked to fertility problems in both men and women. Studies have shown that exposure to air pollution contributes to lower fertility rates. For example, a study found that sperm counts in the west fell by 59% between 1973 and 2011, and that annual rounds of IVF in Australia increased by 2-3% annually, with an 11% jump between 2015-2019.

Furthermore, exposure to environmental toxins during pregnancy can affect the fetus's development and increase the risk of adverse outcomes such as preterm birth, limited fetal growth, and increased gestational diabetes.

Protecting Yourself from Air Pollution During Pregnancy

While it is impossible to avoid all exposure to air pollution, there are some steps that can be taken to reduce the risk to your health and that of your baby:

• Check your area's Air Quality Index (AQI) regularly to stay informed about the air quality and associated health risks.
• Avoid spending time outdoors when the air quality is poor, and consider investing in an air purifier for your home.
• Stay away from smoke and second-hand smoke, and quit smoking if you are a smoker.
• Educate yourself about the effects of air pollution on public health and support efforts to study its impacts on fetal health.

Maternal inflammation

• Low birth weight: Exposure to air pollution during pregnancy has been associated with low birth weight, with one study finding that babies born to mothers exposed to high levels of air pollution during the third trimester were, on average, 0.8 ounces lighter than those born to mothers who were not exposed.
• Preterm birth: According to a study by The Stockholm Environment Institute, nearly three million babies are born prematurely each year due to air pollution, with particulate matter pollution being linked to 18% of all annual preterm births.
• Autism: A Harvard study found that women exposed to high levels of particulate matter pollution during their third trimester were twice as likely to give birth to a child with autism, especially if they lived near a highway.
• Asthma: Air pollution can exacerbate asthma in pregnant women, which can lead to preeclampsia and cause poor growth, premature birth, and low birth weight in the baby. Research has also found that exposure to air pollution can increase the risk of a child developing asthma later in life.
• Fertility problems: Multiple studies have linked air pollution to lower fertility rates in both men and women, as well as an increased risk of miscarriage.

Frequently asked questions