When carbon monoxide enters the body it interferes with the blood’s ability to bring oxygen to all body parts and organs. Without oxygen, the body soon shuts down. In the fetus, carbon monoxide crosses the placenta and reduces the amount of oxygen that is delivered and circulated. This can cause a condition called fetal growth retardation. Although carbon monoxide is dangerous, it’s not necessary to start holding your breath every time you walk outside. A few commonsense precautions will keep your baby perfectly healthy:

Check your furnace for carbon monoxide leaks and get a carbon monoxide detector for your house. Make sure wood-burning stoves, fireplaces, gas heaters, gas stoves, and space heaters are all working properly. All of them can leak carbon monoxide. Check the exhaust system in your car for leaks. Don’t start the car in the garage with the garage doors closed. Keep the car’s air vents closed when you’re in heavy traffic. Avoid jogging, running, walking, or cycling along roads with heavy traffic. Avoid smoke-filled rooms. Try to stay indoors on “smog alert” days.

Millions of healthy babies are born to mothers who live in smog-choked cities and who spend lots of time in smoke-filled rooms. But to be on the safe side, avoid plopping yourself in the middle of a smog-filled or smoky area.