My 18mth old girl has been waking up with an overflowing diaper the
past several days.  She sleeps for 12 hours at night, beginning with a
fresh diaper, and usually has a lightly wet diaper in the morning.  We
have not increased her intake of liquids (milk primarily).  The urine
is much yellower than normal too.  Should we be concerned?

I would definitely report this to your pediatrician. A sudden change
in urinary output should be investigated.

Hi robertoregon, 

As a mom, I would be concerned. A rule of thiumb is, if excessive
urination occurs for more than a couple of days and can't be explained
by medication or increased fluids, then the child should be examined.
There are a number of disorders that can cause excessive urination
and/or excessive thirst (Childhood diabetes for one), and those should
be ruled out.

One trip to the pediatrician and you'll know for sure. Good luck! 

-K~