They will have refused unless there is something we dont from any previous application be cause of lack of funds and/or they dont believe your ties to the Phillipines are strong enough to return at the end of your visit.
Reading this thread I can see why they may think that as you say what you want is the possibility to raise your child here.They probably think is as well
A one week visit could only really be so that the father can see his child and they probably would find this unusual if not suspicious as it would be more normal for the father to visit you cheaper to.
If the child has a UK passport and the reason for your visit had been to for example hand over custody that might not have been such a strange request but we dont know what you said on the application so hard to say more.
You can of course appeal the refusal and even reapply if the reasons to visit were to change