14 weeks pregnant and keep getting a tingly feeling in my fingers.. Pls help?

my sister is 21yrs old and is 14 weeks pregnant! Her pregnacy is normal and healthy but she keeps getting a tingly feelin in her right hand.. It comes and goes through out the day and last for about a half hour! The dr didnt say it was harmful but shes worried on why she gets this feeling! Has any1 else ever got this before and why?? Thanks! :)