The impact of air pollution on maternal health is an increasingly researched topic around the world. A recent study in the city of Baoji, located in a river valley in northwest China, reveals worrying results regarding the relationship between exposure to air pollutants during the first trimester of pregnancy and increased risk of miscarriage .
Reproductive health is threatened by exposure to air pollutants. A pregnant woman may have a miscarriage in the first trimester if she is exposed to air pollution. At least these are the results of a study carried out by a team of Chinese researchers. The study focused on five air pollutants: fine particles (PM 2.5), inhalable particles (PM 10), sulfur dioxide (SO2), nitrogen dioxide (NO2) and ozone (O3). These substances are known to be harmful to respiratory and cardiovascular health, but their influence on adverse pregnancy outcomes has rarely been studied in depth. Through a retrospective analysis of clinical data from pregnant women who suffered miscarriage and others who carried their pregnancies to term, researchers observed a significant link between exposure to certain pollutants during the first trimester of pregnancy and increased risk of miscarriage. The results show that exposure to PM 2.5, SO2 and NO2 during the first trimester of pregnancy is strongly associated with an increased risk of miscarriage. In particular, pregnant women exposed to high levels of PM 2.5 (the finest particles and most dangerous to health) have a 15% higher risk of miscarriage than those whose exposure was lower. Similarly, exposure to sulfur dioxide and nitrogen dioxide, two common pollutants in industrial urban areas, showed similar results, with risks increased by 43% and 12%, respectively. In contrast, PM 10 and ozone concentrations did not show a statistically significant link with increased miscarriages. The results of this study add to a long series of research highlighting the deleterious effects of air pollution on health while the risks were associated with respiratory and cardiovascular diseases. It is now a major public health problem, particularly for pregnant women living in heavily polluted urban areas.
Seasons and pollution concentrations: a key factor
The study also highlighted a seasonal aspect in exposure to pollutants. Concentrations of PM 2.5, SO2 and NO2 are significantly higher during the winter months and spring, due to the burning of coal for domestic heating and unfavorable weather conditions. This phenomenon is all the more worrying because miscarriage rates in the region were also higher during these seasons, suggesting a potential link between peaks in winter pollution and negative pregnancy outcomes.
Awareness of the impact of pollution on pregnant women could lead to stricter air quality policies and information campaigns to raise public awareness of the risks of air pollution during pregnancy. Pollution reduction measures, such as limiting industrial emissions and transitioning to greener heating systems, could help reduce these risks for expectant mothers and their children, researchers say. They call for increased monitoring of air pollutants, particularly in densely populated and industrialized urban areas, and recommend that pregnant women, especially those living in these areas, take steps to reduce their exposure to pollution, such as avoiding heavily polluted areas and limit outdoor activities during pollution peaks.
The study was carried out between 2018 and 2019, in two hospitals in the city of Baoji. The researchers collected data on 154 cases of miscarriage and 616 full-term deliveries, comparing several factors, such as age, occupation, parity, and season of last period. Concentrations of pollutants in the air were measured using two methods: the global average method, which does not take into account the distance between the monitoring station and the homes of pregnant women, and the method of the nearest monitoring station, which adjusts measurements based on geographic proximity to air quality stations.
