Air pollution is a growing global concern and has a major impact on public health.
There is growing scientific evidence resulting from adverse pregnancy outcomes due to exposure to air pollution. It is increasingly recognized as a major threat to maternal and infant health. Pregnant mothers exposed to contaminated environments are at increased risk of complications, including preterm birth, low birth weight, stillbirth, and congenital abnormalities, whether from outdoor air pollution or indoor toxins such as tobacco smoke.
External environmental factors such as air pollution play an important role in disrupting the delicate processes of embryo growth and differentiation.
The study entitled “The role of indoor smoke on open flames and parental smoking on risk of flames and cleft palate: a case-control study in seven low-resource countries” was discussed at the Pan African Surgery Conference, which highlighted the risks associated with indoor air pollution. Research shows that children whose mothers exposed to wood stove smoke during pregnancy were 49% more likely to be born with clefts or palate.
Study participants included children from Vietnam, the Philippines, Honduras, Nicaragua, Morocco, Congo and Madagascar with lips and palates.
In developed countries, cooking on an open flame is rarely exposed to smoke. However, indoor air pollution is widespread in low-resource areas where around 80% of rural households rely on cooking biomass fuels. Many low-resource settings also lack access to corrective surgery, making the lips and cleft palate the most common birth defects.
South Africa is no exception.
A study conducted by the South African Medical Research Council (SAMRC) in collaboration with surgeons, researchers and Operationsmile revealed that pregnant women living in air pollution hotspots are at higher risk of giving birth to children with orofacial clefts.
“Yes, exposure to air pollution during pregnancy is associated with an increased risk of birth defects, such as cleft lip and palate,” said Dr. Charadie Wright, the lead specialist scientist at the SAMRC Environmental and Health Research Unit, and Dr. Charadie Wright, the research principal investigator.
She said new evidence indicates that certain air pollutants, such as particulate matter (PM₂.₅), nitrogen dioxide (no₂), sulfur dioxide (SO₂), and polycyclic aromatic hydrocarbons (PAH), can interfere with fetal development, especially during the early stages of pregnancy, when the baby’s facial structure is formed.
“Some studies have found an association between maternal exposure to high levels of air pollution and increased likelihood of cleft lip and palate,” Dr. Wright said. “Exposure to PM₂.₅ and PAH, commonly released from vehicle exhaust, industrial processes, and biomass burning, is associated with developmental abnormalities in animal and human studies. These contaminants can cause oxidative stress, inflammation, and DNA damage, destroying normal tissue fusions in the developing face.”
Dr. Wright said the risk of air pollution to maternal and fetal health differs significantly between high-income and low-income countries, primarily due to different sources of pollution, access to health care, and mitigation strategies. In low-income countries, women are frequently exposed to high levels of household air pollution due to the burning of biomass fuels such as wood, charcoal and feces for cooking and heating. This exposure is associated with adverse outcomes such as low birth weight, premature birth, death, and birth disorders. Furthermore, outdoor air pollution caused by traffic, industry and dust contributes to respiratory disease and pregnancy complications.
She said limited access to health care in these areas exacerbates health risks as pregnant women may not receive timely prenatal care or intervention.
“In contrast, high-income countries benefit from stricter air quality regulations, better healthcare infrastructure and improved access to cleaner energy sources,” Dr. Wright said. “However, urban air pollution is primarily due to traffic emissions, industrial activities and wildfires — a concern.”
Wright said studies in high-income countries have shown that exposure to contaminants such as particulate matter (PM₂.₅) and nitrogen dioxide (no₂) can increase the risk of preterm birth, low birth weight and developmental problems. Even when pollution levels are low compared to low-income countries, prolonged exposure to air pollution can have subtle but significant effects on maternal and fetal health.
“Different regions are taking different approaches to addressing the risk of air pollution during pregnancy,” she said.
She said high-income countries have successfully reduced contamination-related pregnancy complications through clean air policies and public recognition campaigns.
“High-income countries are implementing strict emission controls, air quality monitoring systems and public health campaigns to raise awareness about pollution-related risks,” Dr. Wright said. “For example, European cities have introduced low-emission zones, and the US has strengthened clean air policies and led to measurable reductions in pregnancy complications related to air pollution.”
She said initiatives such as providing clean cooking stoves, promoting renewable energy and expanding maternal health services will help reduce exposure to harmful contaminants in low-income countries.
Lessons from both settings suggest that a comprehensive policy that combines reduction in pollution and improved healthcare is essential, Dr. Wright.
“Low-income regions can benefit from investments in clean energy, air quality monitoring and accessible maternal health care, while high-income regions must continue to improve their pollution prevention strategies, particularly in urban areas,” she said. “Collaboration across regions, including sharing research on contamination-related pregnancy risks and implementing proven interventions, can help mitigate these risks globally.”
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Dr. Wright said policymakers and public health officials need to find better ways to implement air quality laws, standards and surveillance. This includes resources and capacity, so tracking air quality and implementing minimum emissions licenses is also important for the polluting industry.
She said many pregnant women remain unaware of the risks that air pollution poses to fetal development. Public health campaigns often focus on smoking, nutrition and prenatal care, but do not highlight air pollution as a risk factor. Access to reliable health information is often limited in low-income and rural areas where contamination exposure is likely to be the highest.
She said many households may not have the means to switch to cleaner energy sources, leaving them vulnerable to the harmful effects of indoor air pollution.
“We need to better understand the connection between exposure and birth outcomes, and we also need to understand when there is a window into exposure during pregnancy that leads to this outcome. This will help improve guidelines for pregnant women and policymakers,” Dr. Wright said.
