Large congenital nevi form in the womb very early in development, within the first twelve weeks of pregnancy. They are caused by a defect during embryologic development. There is no known method of prevention. They appear in either sex, in all races, and on any areas of the skin.
I recommend that you have a carbon monoxide detector within 15 feet of each bedroom door, 10 feet is even better if you can afford more detectors. If two bedroom doors are 30 feet apart or less, then place one in the middle. If however they are more than 30 feet apart you will need more than one detector.
Carbon monoxide can seep into your home through vents and doors. 6) DO I NEED A CARBON MONOXIDE (CO) ALARM? WHERE SHOULD IT BE INSTALLED? Every home with at least one fuel-burning appliance/heater, attached garage or fireplace should have a carbon monoxide alarm. If the home has only one carbon monoxide alarm, it should be installed in the main bedroom or in the hallway outside of the sleeping area. An alarm should be installed on every level of the home and in sleeping areas. Place the alarm at least 15 feet away from fuel-burning appliances.