Hi J.:
Below, I added an explaination,concerning toddlers,and bladder control. Its my thought,that your reading more into this,than there is.There are many toddlers, slower in their maturity to control their bladder. A doctor doesn't even consider wetting a Problem,until a child reaches 11 or 12. Alot of times, children can experience relapses. This can be created,by Moving residence,break ups,or any number of changes in their life.If she is petite in size(having a small bladder,and is a deep sleeper, this will slow her progress as well. I would be patient,and give your daughter the time she needs to develop.I wish you and your toddler the best.
In the infant, urination/voiding/micturition is purely a local reflex centered in the lower portion of the spinal cord. In infants two years old and under, involuntary voiding occurs whenever the bladder is sufficiently full. This results in stretch receptors in the urinary bladder wall transmitting impulses to a special area in the spinal cord known as the sacral micturition center. The sacral micturition center responds by causing detrusor muscle contraction of the bladder.
Between the ages of 2 and 3 as the child's nerves, muscle and brain mature, a special area in the brain gradually develops. Simultaneously, the development of special nerve pathways to that center allows the child to detect a sensation of bladder fullness.
The next stage in the child's maturity occurs when the area in the lower part of the brain, known as the pontine micturition center, develops enough to coordinate sphincter relaxation during voiding.
During the last stage of development, the young child learns conscious bladder control , and during toilet training, develops the ability to inhibit the bladder center in the lower spine (back). Continence during sleep results from the unconscious inhibition of detrusor muscle contraction by an area in the brain known as the basal ganglia).