Without details, it's impossible to say. UC works by adding up elements of entitlement, then deducting a portion of your income.
Anyone who applies is entitled to the standard allowance. For a couple with one person over 25 it's £628.10
For the first two children, you can get £292.81 each.
So if this is your first baby, that takes your base entitlement up to £920.91
Then, if you rent, you'll get a rent allowance of either your whole rent if you rent from the local authority, or the Local Housing Allowance rate for your area. If you have a mortgage, you don't get any allowance.
Then, if you pay for approved childcare, you get 85% of the amount you pay, up to a limit.
All of this is added up.
Then your total wages after deductions have a work allowance deducted from them (it's slightly higher if you have a mortgage), and then 55% of the remainder is deducted from your total allowances.
If the remaining figure is positive, you get a UC payment of that amount. If it is negative, you don't get UC.