In some cases that is true. It varies person to person and the extent of their PWS.
I have used a couple different creams some work better then others. Some are not reccomended for child unless made in low dosages.
Regardless of numbing cream or not laser treatment will take a very long time and in some cases is not going to ever completely remove a birthmark. It might help the birthmark from getting worse, but every person is different.
In my case I have a deep PWS on my face. I am 26 years old and started laser treatment when I was 5 years old, have had 3 plastic surgeries, and I still have most of my PWS.
Darker the PWS is the harder it will be to remove with or without numbing cream. If you would like to see pictures of when I had treatment and surgeries my website is www.hankspws.com
Like I said earlier laser treatment will take time. If you are seeing improvements already after six treatments then you have made good progress. What type of laser are you using. My favorite out of the four different lasers I have used is the V-Beam Pulse Dye Laser and is safe on young children.
I would find out from your doctor what settings he or she is using and talk about options. Ever doctor is going to be different in how comfortable they are with the machine. Most will not go to stronger settings with younger children because of the chance of scarring.
I hope this helps a little.
I am sure other parents will chime in soon.
If you have any other questions you can either email me or ask here on the support group.