Air Pollution Has Adverse Effects on Pregnancy In one study, it is noted that black carbon particles – or soot – could cross the placenta. The Nature Communications research is the first direct evidence that particles can enter the placenta fragment that feeds the developing fetus. It may be the first step to explain why high pollution is associated with the risk of miscarriage, preterm birth and low birth weight risk. Experts said that women can take measures such as avoiding busy roads. However, they warned that the fight against air pollution can only be at the “policy level”.