Can air pollution affect pregnancy outcomes?

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Air pollution can negatively affect pregnancy, possibly leading to preterm birth, a low birth weight, stillbirth, or congenital abnormalities.

People who live in polluted areas or have exposure to indoor air pollution from toxins such as cigarette smoke have higher rates of negative pregnancy outcomes.

In this article, learn more about how air pollution can negatively affect pregnancy. This article also covers how to reduce the effects of pollution.

Potential effects of air pollution on pregnancy

Pregnant woman in the polluted city.
Image credit: Getty Images

Air pollution can affect the health of the pregnant person and the developing baby. Contaminants in the air can cross the placenta, affecting the health of the placenta itself and disrupting the baby’s development.

The specific effects of air pollution depend on several factors, including:

  • when in development the baby has exposure to the pollutant
  • how long the exposure lasts, and how much pollution there is
  • the specific pollutant

Other factors may interact with pollution to either mitigate or increase the risk. Most research suggests that groups who are more vulnerable to congenital abnormalities are also more likely to live in polluted areas.

For parents with a low income or those from minority groups, other risk factors — such as exposure to racism and lack of access to quality food, good prenatal care, or safe homes — may intensify the effects of air pollution.

Air pollution comes in many forms and can be indoors or outdoors. Some types of air pollution include:

  • outdoor air pollution from smog
  • indoor and outdoor pollution from fire and smoke, including tobacco smoke
  • occupational hazards, such as working outdoors, working with toxic chemicals, working with animals, and working in industrial areas
  • household chemicals, such as asbestos
  • dangerous chemicals, such as some cleaning supplies and paint
  • allergens, such as mold

Air pollution and pregnancy outcomes

Researchers have not yet identified all the potential effects of air pollution. Also, doctors do not know why air pollution causes harm to some pregnancies but not others.

There is no way to predict who will or will not experience negative pregnancy outcomes, though experts do currently believe that exposure to air pollution increases the risk.

Some potential effects of air pollution during pregnancy include:

Preterm labor

Pregnant people who live in polluted areas may be more likely to experience early, or preterm, labor.

Preterm labor increases the risk of other problems, such as low birth weight, underdeveloped lungs in the baby, and death of the baby during or shortly after birth.

One 2019 study assessed the effects of common pollutants, such as ozone, sulfur dioxide, nitrogen oxide, and nitrogen dioxide. It found a correlation between air pollution and preterm labor. The risk was highest during a subsequent pregnancy.

This study, like most studies into air pollution, established a correlation. It did not prove that air pollution causes preterm labor. Other factors might explain the higher prevalence of preterm labor, or people who live in polluted areas might simply be at a higher risk of having other risk factors for early labor.

Stillbirth

Stillbirth refers to the death of the baby late in pregnancy, after 20 weeks.

One 2018 study established a correlation between exposure to air pollution and stillbirth. The risk was highest during the third trimester of pregnancy.

Low birth weight

Exposure to air pollution may disrupt a baby’s development, causing them to be born unusually small. It can also cause preterm delivery, resulting in very small babies with underdeveloped bodies and lungs.

Low birth weight is a risk factor for developmental delays, numerous health issues, and death after birth.

One 2013 analysis of 14 population-level studies found that a higher prevalence of certain pollutants, such as nitrogen dioxide, correlated with a higher risk of low birth weight.

This does not prove that pollution causes low birth weight, but it does establish a potential connection between the two.

Health concerns in the parent

Exposure to air pollution correlates with a higher risk of pregnancy-related complications in the parent.

A study of birth outcomes in Allegheny County, PA, found that exposure to air pollution in the first trimester increased the risk of preeclampsia and high blood pressure. These complications can harm the parent and the baby, and this may necessitate an early birth.

The findings also support the results of other studies, which have established a link between pollution exposure and low birth weight and preterm labor.

Lung development issues

Exposure to air pollution may affect lung development. In some babies, this occurs indirectly, when preterm labor causes a baby, whose lungs are not fully functional to be born. This is a risk factor for death after birth.

Exposure to air pollution is also linked to longer-term respiratory issues, such as asthma and allergies.

How to prevent or reduce negative effects of air pollution

People cannot usually control the levels of pollution around their home or workplace. There are, however, a few things a person can do to reduce the effects of polluted air.

For example:

  • Evacuate to a safer area when air quality is very dangerous, such as during a wildfire. Also, during wildfire season, avoid buying groceries that require cooking, as this can worsen indoor air pollution.
  • Have the home inspected for asbestos, then work with the asbestos advisor to develop a plan to reduce the danger, if necessary.
  • Install a carbon monoxide detector to prevent carbon monoxide poisoning.
  • Have the home inspected for mold, and hire a professional mold remover, if necessary.
  • Wear a face covering when using cleaning products or paint.
  • Do not smoke inside or allow anyone else to do so. Ask people who smoke to change their clothing before coming into the house.
  • Install a high efficiency particulate air filter to reduce indoor air pollution.
  • Avoid going outside during very polluted times. Most local weather stations report on daily air quality, particularly in polluted regions.
  • Talk to a medical professional about other tips to reduce the overall risk of pregnancy complications related to air pollution.

Summary  

Air pollution is a serious health risk for both the pregnant person and the baby they are carrying. It may also interact with other risk factors, intensifying the risk for the most vulnerable families.

People who live in polluted areas, who live with individuals who smoke, or who worry about air pollution can discuss these concerns with a doctor or midwife.

Simple protection strategies — such as remaining indoors as much as possible, wearing a face covering when outdoors, and using quality air filters — may reduce the harmful effects of air pollution on pregnancy.

Last medically reviewed on October 29, 2020

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