What Causes Colorless Raised Moles On Leg After Childbirth?

Hi after my first daughter was born in May of 2009 I noticed the development of a colorless mole on the back of my leg. My family doctor wasn't terribly concerned. Since the birth of my second daughter on new years day of this year (10 weeks ago) I have discovered 3 more. They are all small and flesh colored with regular shapes, just slightly raised and they cause no discomfort. Is this something that can occur post natal and is it something I should be concerned about or just keep an eye on?