A group of researchers from Milan's Università Statale has found that environmental pollution reduces gestational age and increases the risk of caesarean delivery, possibly due to changes in the LDL cholesterol protein.
A new entry has been added to the list of negative health effects of fine particulate matter on women expecting a child: an increase in "bad" cholesterol. The phenomenon may be due to the abnormal reaction of a specific protein to air pollution, and the consequences for pregnancy are far from trivial.
Chiara Macchi and her colleagues at the Università degli Studi di Milano monitored circulating levels of the protein responsible for LDL cholesterol production, Pcsk9, in 134 healthy women at the twelfth week of gestation. The aim was to assess whether this protein could serve as an early biological marker — a kind of early warning sign for potential complications.
"Cholesterol is essential for foetal growth. We asked ourselves whether environmental pollution could affect the presence of the protein that regulates its blood levels, and whether these effects could translate into a negative impact on intrauterine growth," explains Macchi.
Together with her research group, coordinated by Alberto Corsini and Massimiliano Ruscica of the Department of Pharmacological and Biomolecular Sciences, she analysed the Pcsk9 values found in blood samples from all participants.
The Arpa monitoring stations spread across Lombardy provided the data for the second step: daily monitoring of air quality. By cross-referencing these two different parameters, it was possible to calculate the level of environmental exposure for each participant at their place of residence throughout the entire duration of the pregnancy.
For Macchi, the result demonstrates a clear link between the inhalation of fine particulate matter and risks for unborn children: "We demonstrated that women exposed to higher concentrations of particulate matter show higher circulating levels of Pcsk9, associated with a shorter gestational age and a greater risk of requiring a caesarean delivery."
Specifically, gestational age at birth is reduced by approximately one week for every increase of 100ng/mL in circulating protein levels, particularly in connection with PM2.5 fine particulate matter. These data were supported by an increase in the odds ratio for emergency caesarean deliveries for every 100ng/mL increase in Pcsk9, trends observed both when considering exposure to PM10 and to nitrogen dioxide (NO2).
Why does this happen? It is impossible to answer precisely, as the molecular mechanisms behind these reactions are not yet known. Nevertheless, Macchi puts forward a hypothesis: "Both pollution and the Pcsk9 protein could stimulate an inflammatory process localised in the placenta, consequently making a caesarean necessary. But it is only an idea, and we are already working to prove it."
Further, more in-depth research will be needed to learn more. In the meantime, the Italian study has been published in the specialist journal Environment International and recently received a grant as part of the prestigious Prix Galien Italian 2022. A recognition that opens the door to new and valuable collaborations, and which it is hoped will once again draw the attention of the international scientific community and institutions to the close link between the climate crisis, health and social justice.
All too often, it is minorities who suffer the most severe consequences, as in the case of African American mothers and their premature, underweight or stillborn babies. The message is clear, the Milan team reiterates: there is no safe threshold. Our health only begins where greenhouse gas emissions end.