Q: As a new parent, I have a lot of questions about toilet training. What can you tell me about this?

Philip E. Gleason, MD, pediatric neurologist practicing at Cardon Children’s Medical Center

A: Toilet training can be one of life's greatest accomplishments and greatest frustrations.

Toilet training usually occurs during ages three and four. In many respects, this represents a natural maturation of the bladder. At birth, emptying the bladder is an automatic reflex. When the child makes urine and the bladder fills up, the body will sense the full bladder and the bladder will squeeze and empty as an automatic reflex, more or less on auto-pilot. Parents can expect to change diapers 8-10 times a day.

As the child grows and develops, the automatic reflex of the bladder will begin to relax and the child can begin to take control of the bladder. As the bladder fills up, the child can sense and feel the bladder.

While this sounds simple, it does appear to represent a fairly complex process. In many respects, the bladder is being asked to do two opposite things. On the one hand the bladder is being asked to relax and store urine for several hours without leaking. Then the bladder is being asked to void and empty completely to allow the cycle to start over. This may, in fact, account for the fact that toilet training occurs after children learn to speak and walk and reach some other fairly complex developmental goals.

To accomplish toilet training, the bladder size, or capacity, needs to be adequate to hold three to four hours worth of urine. In addition, the brain and central nervous system begin to take control and relax the bladder to hold urine. Last, at night, a hormone known as anti-diuretic hormone helps cut down how much urine is made through the night, to help sleep through the night without having to get up.

Once the bladder is full, the bladder muscle contracts to squeeze and empty the bladder. In addition, the sphincter muscles which also help hold urine relax and allow the bladder to empty completely. The sphincter muscles then regain their muscle tone to close the bladder and the cycle starts all over again.

The body goes through a fairly specific sequence of toilet training. First, you get control of the bowels at night. Second, you get control of the bowels during the day. Third, you get control of the bladder during the day. Fourth, and last, you get control of the bladder at night.