Bacteria on UA

Hi I am 8 weeks pregnant and during my first prenatal visit my result of urinalysis shows an increase count of bacteria in my urine sample . i was prescribed cefalexin 2 x a day for 5 days. I am reluctant to take one for i am afraid it may harm my baby. can i ask if anyone of you here have been prescribed with cefalexin or had an elevated bacteria result in urinalysis. thanks in advance.