Health Desk- 18 Sep 2019: Particles of black carbon - or soot - can cross the placenta, acording to a study.
The Nature Communications research is the first direct evidence the particles can get into the part of the placenta that feeds the developing fetus.
It could be the first step to explaining why high pollution is linked to an increased risk of miscarriage, premature birth and low birth weights.
Experts said women could take measures such as avoiding busy roads.
But they warned tackling air pollution could be achieved at a "policy level" only.
Oxygen and nutrients cross from the maternal placenta to the fetal placenta and are then carried to the fetus via the umbilical cord.
Waste products from the fetus, such as carbon dioxide, pass back the other way.
In-between is a semi-permeable membrane, made up of placental tissues
Substances such as alcohol, nicotine and other drugs are known to be able to cross the placenta, which is why women are advised to avoid them during pregnancy.
Courtesy: BBC Health