Q: My 4-year-old loves the swimming pool, but she seems to begin shivering and her lips turn blue almost as soon as she gets in the water -- even on a very hot day. Should I make her get out?
A: Blue lips and shivering are both signs that your daughter's body is adapting to a rapid change in environmental temperature. It's not surprising that you see these signs when she enters the pool on a very hot day, because the water is probably much cooler than the air.
It is the body's business to keep at an even and safe temperature at the body core where the life-sustaining organs are (brain, heart, liver, etc.). The body is carefully designed to regulate this temperature, but it does so partly by making changes in the skin and muscles.
In a hot environment, sweating begins. Evaporation of the sweat draws heat from the body. The body also sends lots of blood to the small vessels in the skin, taking heat to the skin where it can escape.
When your daughter moves from the hot air into the cool pool water, her body must quickly readjust its temperature control mechanisms. Blood flow is redirected from her skin and lips look blue. She begins to shiver which, through many small muscle contractions, helps to create heat. Once this resetting has taken place, your daughter should begin to look much more comfortable in the pool. You can speed it along by encouraging her to begin playing or swimming. Her movements will require her large arm and leg muscles to contract -- a great source of heat.
If your child is shivering and blue to the point of discomfort, she can get out of the pool and dry vigorously with a towel. Rubbing and drying the skin will warm her up quickly.
Dr. Wilson is director of general pediatrics at the Johns Hopkins Children's Center; Dr. Joffe is director of adolescent medicine.