A study conducted at UCLA has shown that in areas where toxic exhaust emissions such as carbon monoxide and particulate matter are at high levels, mothers are up 25% more likely to have preterm babies. More details regarding this study can be found in an article by United Press International.
This adds another potential danger to the long list of problems created by incomplete combustion of hydrocarbon-based fuels. The advantage to hydrocarbon fuels is that they are plentiful, and they burn easily. Those are the main reasons why the market has created engines that burn gasoline and diesel. The downside to them is that they are actually fairly difficult to completely convert to energy. The thermal efficiency of really efficient engines is only a little better that 40%. The rest of that energy is wasted in several places, one of which is incompletely combusted toxic emissions.
Biofriendly innovations like Green Plus can make a big difference to problems like this. A government certified test completed by Petroecuador, that national oil company of the country of Ecuador, showed that Green Plus significantly reduced Carbon Monoxide, one of the emissions found by UCLA to be responsible for the increase in preterm babies.